1 00:00:08,490 --> 00:00:12,270 So welcome to this Friday's colloquium. 2 00:00:12,690 --> 00:00:17,280 It's a great pleasure to introduce in Chip C, who's today's speaker. 3 00:00:18,690 --> 00:00:22,530 Ian has a distinguished record as an experimental particle physicist. 4 00:00:23,400 --> 00:00:26,510 He's worked on a number of well-known experiments. 5 00:00:26,520 --> 00:00:31,140 He was a very senior member of the CMS collaboration, which discovered the Higgs boson. 6 00:00:31,920 --> 00:00:35,430 He's now moved to Atlas Plus after moving to Oxford. 7 00:00:35,640 --> 00:00:39,230 He's also a senior member of the LHC collaboration. 8 00:00:39,240 --> 00:00:47,250 That's a large synoptic survey telescope. And he has a very, very long reputation in in these areas. 9 00:00:47,700 --> 00:00:54,150 He moved to Oxford a few years ago to occupy what was then known as a professorship of experimental physics. 10 00:00:54,510 --> 00:01:00,690 As those of you who really read your email will see that we finally succeeded in getting this called something sensible. 11 00:01:00,930 --> 00:01:06,960 So in is now the Henry Moseley Centenary Professor of Experimental Physics at the University of Oxford. 12 00:01:07,290 --> 00:01:12,390 And it's great pleasure to introduce him to talk back to us today about something completely different. 13 00:01:12,810 --> 00:01:19,440 I want to carry it. Okay. Thank you for the invitation to speak today. 14 00:01:21,760 --> 00:01:26,080 In October 1989, I had perfect terror. 15 00:01:27,410 --> 00:01:31,280 But by the end of the year, I had no hearing whatsoever. 16 00:01:32,580 --> 00:01:38,550 It began when I could not hear the quiet passages of music on a car radio. 17 00:01:39,690 --> 00:01:45,460 That day. Turning up the volume helped. But soon there was no more music. 18 00:01:46,600 --> 00:01:50,680 At the same time, the voices of friends of the family receded. 19 00:01:51,670 --> 00:01:57,610 And I entered a world of silence. The reason for my deafness. 20 00:01:58,570 --> 00:02:03,610 Was a medically necessary dose of O2 toxic antibiotics. 21 00:02:04,650 --> 00:02:07,620 That destroyed the households of my country. 22 00:02:09,410 --> 00:02:19,700 The reason for the antibiotics was earlier that year I had contracted acute myelogenous leukaemia, a truly terrible form of cancer. 23 00:02:21,010 --> 00:02:26,440 But thanks to friends in Syracuse, Rockefeller and especially Cornell University. 24 00:02:27,320 --> 00:02:33,380 I received first rate medical care at the Cornell University Medical College in New York City. 25 00:02:34,850 --> 00:02:39,260 An industrial strength dose of chemotherapy beat the cancer. 26 00:02:40,260 --> 00:02:44,850 But it left me without an immune system and the antibiotics protected me. 27 00:02:45,510 --> 00:02:57,440 And so my own immune system had virtually. For those that can hear suddenly losing hearing is a terrible disability. 28 00:02:58,920 --> 00:03:05,220 Without an appropriate support network, a person so afflicted can withdraw from society, 29 00:03:05,820 --> 00:03:11,700 can become depressed, can sometimes turn to substance abuse and even to suicide. 30 00:03:13,530 --> 00:03:16,740 For most of us citizens who lose hearing as they age. 31 00:03:17,370 --> 00:03:26,670 Studies show they leave the workforce years earlier than they otherwise would do, and from then on made less fulfilling and productive lives. 32 00:03:28,150 --> 00:03:33,580 Children born deaf was sent to schools with children who can have. 33 00:03:34,420 --> 00:03:37,630 They lack the ability to develop an oral linguistic tradition. 34 00:03:38,530 --> 00:03:46,540 That if school at the age of 18 with the reading age of a 12 year old and that is it got too large, too close. 35 00:03:47,680 --> 00:03:56,290 Fortunately, science and technology are coming to the rescue to treat many difficult conditions in our lives, including deafness. 36 00:03:56,920 --> 00:04:01,720 And in this talk, I want to talk about one of those technologies, the cochlear implant. 37 00:04:02,810 --> 00:04:08,480 And so the outline of the talk will began by looking at the natural physiology of hearing. 38 00:04:09,560 --> 00:04:16,760 And then the causes for deafness, the solutions to hearing loss, in particular the cochlear implant. 39 00:04:17,300 --> 00:04:22,430 I briefly talk about some of the political and social issues that surround this 40 00:04:22,610 --> 00:04:28,400 still somewhat controversial technology and for looking at the future of implants. 41 00:04:30,550 --> 00:04:36,430 So as most of you know, sound is a form of mechanical energy. 42 00:04:37,150 --> 00:04:45,250 When you strike the times of a tuning fork, the oscillatory motion of the times nearby air molecules into oscillatory motion, 43 00:04:46,030 --> 00:04:50,590 and then turns more distant and molecules into oscillatory motion. 44 00:04:51,040 --> 00:04:58,700 And in this way, sound passes through the air as a molecular disturbance until it arrives at piano or airflow. 45 00:05:00,230 --> 00:05:03,110 The events that occur after that are truly remarkable. 46 00:05:03,770 --> 00:05:09,510 And so I'd like to show you that them using a unemotional that's been developed by a friend of mine, Brandon Platt. 47 00:05:09,530 --> 00:05:17,590 She was a young medical illustration test from Georgia. Some years ago, it won first prize in the National Science Foundation, 48 00:05:17,640 --> 00:05:22,790 American Association for Advancement of Science, Science, Engineering Visualisation Challenge. 49 00:05:23,390 --> 00:05:28,720 And in this presentation, it's been heavily edited by one of my graduate students and myself. 50 00:05:33,000 --> 00:05:39,960 Says Sound arrives at the peanut and the peanut collects the salad and follows it down onto the ear canal. 51 00:05:40,530 --> 00:05:45,120 And then it arrives at the tympanic membrane or eardrum, which is about a centimetre across. 52 00:05:47,070 --> 00:05:51,420 And the tympanic membrane vibrates in response to sound. 53 00:05:56,230 --> 00:06:00,400 How is the violin? Can you hear it? No. Good. 54 00:06:01,360 --> 00:06:08,380 So the tympanic membrane is conical in shape, and it is articulated by three small bands collectively called the Usher Cleaves. 55 00:06:08,620 --> 00:06:14,080 The Malleus will hammer the increase or anvil, both about one centimetre in length. 56 00:06:14,480 --> 00:06:19,000 And the staples of the stapes is the smallest bone in the human body. 57 00:06:20,200 --> 00:06:26,130 And it's through these also claims that the vibrations of the tympanic membrane are transmitted to the piece. 58 00:06:35,320 --> 00:06:41,940 Now the stage moves with a piston like action at the oval window of the pony lover. 59 00:06:42,950 --> 00:06:50,900 The body lava instilled with a fluid shown here in purple that similar to cerebral spinal fluid. 60 00:06:51,620 --> 00:06:53,510 Now, fluid is relatively incompressible. 61 00:06:54,170 --> 00:07:01,400 And so the piston like action of the state piece would not be able to transfer energy to this system unless the fluid volume was conserved. 62 00:07:02,120 --> 00:07:08,330 And so this is achieved by a flexible membrane called the round window, which moves in synchrony with the state. 63 00:07:08,540 --> 00:07:14,150 So what about preserving fluid volume and allowing sound energy to enter the body lateral? 64 00:07:15,730 --> 00:07:25,450 Now The Bone elaborates itself is about few centimetres across and has two organs a semicircular organs and balance and ingrain this no shape culture. 65 00:07:26,470 --> 00:07:30,310 Vibrations from the state piece enter into the helical structure. 66 00:07:30,700 --> 00:07:34,960 They rise to its apex and they send the gun to the round window. 67 00:07:36,250 --> 00:07:45,220 In more detail. The court player consists of two principal dogs called Scarlett the Scott of a snippet in which the vibrations rise to the apex. 68 00:07:45,550 --> 00:07:51,400 The Scarlett Symphony, in which they descend to the round window. And each of these dogs is about a millimetre across. 69 00:07:52,210 --> 00:07:59,620 And there's a third duck called the Cochlear Duck shown here in purple, and that's filled with potassium rich solution. 70 00:08:00,310 --> 00:08:03,590 And this cochlea is intricate and it is small. 71 00:08:03,610 --> 00:08:11,060 It's about the size of a chickpea. And the reason that's so small is to enable it to be very light and sensitive to low levels of sound vibration. 72 00:08:12,620 --> 00:08:13,759 And forms earlier. 73 00:08:13,760 --> 00:08:23,600 This is the excited human cook and a child at six months gestation at birth, the cochlea is fully formed and it is fully functional. 74 00:08:26,390 --> 00:08:28,580 Now, if we increase the magnification further, 75 00:08:28,580 --> 00:08:36,830 we see that the skull are separated from each other by two membranes was membrane and the vascular membrane. 76 00:08:37,040 --> 00:08:44,780 These two membranes are flexible. And so when vibrations pass through the fluids of the scarlet, it produces a deflection. 77 00:08:45,020 --> 00:08:54,140 In these membranes. Now in the lower of these two membranes, on the back of the membrane, there's a specialised organ called the organ of Culture. 78 00:08:54,710 --> 00:09:06,230 And when this organ is stimulated by flexing it shown here in green, it produces electricity that passes to the order of and up to the brain, 79 00:09:06,770 --> 00:09:13,160 where the auditory down fills the hollow modulus of the cochlea and innovates to the punch and talk. 80 00:09:13,200 --> 00:09:23,820 35 millimetre helical length. And the origin of these electrical signals of specialised cells called hair cells. 81 00:09:24,540 --> 00:09:28,710 One wrote about a house in a house that was in three rows of out of her cells. 82 00:09:29,430 --> 00:09:37,280 And there's other this house has a built over the muscle membrane and protected and covered by a gelatinous membrane called the tournament. 83 00:09:38,430 --> 00:09:44,489 When the sound causes the mass of the membrane to be displaced, the cilia or has a top to her. 84 00:09:44,490 --> 00:09:52,729 So some actually derives their name are flexed and they cause the cells to trigger and produce electricity that passes to the brain. 85 00:09:52,730 --> 00:10:02,400 And so the house owes on the corner and that trickle transducers and we have about 16,000 of these households in each of our healthy cochlear. 86 00:10:04,120 --> 00:10:09,430 Now the bachelor member itself does not respond simultaneously to sound. 87 00:10:09,940 --> 00:10:18,580 Instead, it responds that the apex of the bass, the membrane, resonates at very low frequencies of sound, 88 00:10:19,750 --> 00:10:24,490 and the base of the bass of the membrane resonates at high frequencies of sound. 89 00:10:24,910 --> 00:10:28,239 And so the bachelor membrane is a frequency analyser. 90 00:10:28,240 --> 00:10:33,940 It's how we know pitch. And we refer to this as a topic organisation. 91 00:10:34,750 --> 00:10:39,530 Well, topic organisation means the relationship between pitch and place, 92 00:10:39,550 --> 00:10:43,300 and you'll see that this is quite important in understanding the cochlear implant. 93 00:10:43,780 --> 00:10:50,890 So what I have here is a ton of topic map of the cochlea showing the frequencies at which it resonates. 94 00:10:51,400 --> 00:10:55,480 Well, the cochlear is very small, less massive, very stiff. 95 00:10:55,600 --> 00:11:00,700 It has a very high resonant frequency, about 20,000 cycles, a second, 20,000 hertz. 96 00:11:01,150 --> 00:11:07,180 And at the base. But it's more massive and less stuff that resonates at around 100 hertz. 97 00:11:07,180 --> 00:11:09,700 And this sets the range of our natural hearing. 98 00:11:12,210 --> 00:11:18,510 Now, some of you know that physicists have played a rather big role in developing this understanding of how we hear. 99 00:11:19,810 --> 00:11:29,920 Helmholtz was the first to recognise that the basilar membrane was a frequency analyser and the brilliant Hungarian biophysicist 100 00:11:29,920 --> 00:11:38,739 George one Becker won the Nobel Prize in 1961 for medicine or physiology for the experimental observation of Sun Atomic Organisation, 101 00:11:38,740 --> 00:11:40,630 which had actually done through years prior. 102 00:11:42,810 --> 00:11:52,020 And so what he actually did was experimentally measured how much of the membrane is displaced and a human cut of it as the pitch is varied. 103 00:11:53,860 --> 00:11:58,720 Now in those days, the 1930s, the technique was rather they only have as a microscope. 104 00:11:58,810 --> 00:12:01,750 So we had to see very big displacement to move to the wavelength of light. 105 00:12:02,080 --> 00:12:05,410 And this meant that we had to have very loud sounds, bigger sounds, bigger displacement. 106 00:12:06,580 --> 00:12:10,240 And so this is some of this data from the 1930s. Well, the Nobel Prize. 107 00:12:10,540 --> 00:12:16,510 This is the base of the base of the membrane. This is the apex, about 35 millimetres in total. 108 00:12:17,020 --> 00:12:21,100 This axis is displacement. And these are extremely loud sounds. 109 00:12:21,970 --> 00:12:30,030 And you can see that as the frequency is reduced, the place that resonates as the most displaced moves gradually towards the apex. 110 00:12:30,070 --> 00:12:35,350 And this was the experimental evidence for turning trophic organisation. 111 00:12:38,030 --> 00:12:45,200 Now it turns out that it's very easy to reproduce the shapes that he saw with mechanical models. 112 00:12:45,500 --> 00:12:50,390 And this was done shortly after the observations are continued for much of the rest of the 20th century. 113 00:12:51,380 --> 00:12:56,000 And so what we have here is the base, and this is the apex right over here and the base of the membrane. 114 00:12:56,010 --> 00:13:00,850 I'm showing just half of it unwrap. This is displacement and that image. 115 00:13:01,010 --> 00:13:06,500 And we're putting it aside the pure tone, which is ten kilohertz, quite a high tone in this case. 116 00:13:07,720 --> 00:13:11,150 And what you can say is quite a lot of the Barcelona and Venice displays. 117 00:13:12,160 --> 00:13:16,590 And if we're not change the input time to 20 kilohertz, doubling the frequency, 118 00:13:16,590 --> 00:13:20,850 they may expect the displacement to move towards the base, which it does. 119 00:13:20,860 --> 00:13:25,080 But you also say that it still overlaps a lot with the Ten Kilohertz Club. 120 00:13:26,300 --> 00:13:33,410 And so what these models actually predict is that the frequency selectivity or pitch perception of the human is rather poor. 121 00:13:34,010 --> 00:13:37,220 We can tell differences between high and low, but it's all kind of mixed together. 122 00:13:38,320 --> 00:13:43,030 And this is in stark contrast with the sacrifices that we actually have. 123 00:13:44,290 --> 00:13:47,520 I see. It's 256 Hertz and C-sharp. 124 00:13:47,530 --> 00:13:52,840 It's like the sublime. Humans can tell 1/10 the difference between C and shot. 125 00:13:52,870 --> 00:14:00,550 That's one hertz 256. So a model like this cannot explain such exceptional ability to recognise pitch. 126 00:14:01,760 --> 00:14:06,800 At the same time, there's a second mystery, and that is how do we actually hear some sound at all? 127 00:14:08,810 --> 00:14:12,320 Think about walking through water and compare it to walking on land. 128 00:14:12,710 --> 00:14:16,460 It's much easier on dry land because the water doesn't resist the ocean. 129 00:14:16,880 --> 00:14:20,300 Here we have a butterfly membrane and it's sitting in fluids. 130 00:14:20,840 --> 00:14:22,910 And so the fluid should damp down the mouth. 131 00:14:26,330 --> 00:14:31,970 Unless there's a significant displacement due to some form of amplifier, something driving the displacement. 132 00:14:32,970 --> 00:14:41,550 And this idea was first suggested by another physicist, the maverick astrophysicist Tommie Gold, in 1945. 133 00:14:42,630 --> 00:14:47,680 And at the time his ideas were ignored. You could say they fell on deaf ears. 134 00:14:48,940 --> 00:14:53,890 And the reason for this was twofold. First, because he was an astrophysicist, not a physiologist. 135 00:14:54,910 --> 00:14:59,140 But the second reason was because his ideas were not really well understood. 136 00:14:59,200 --> 00:15:04,100 Most people got the idea that, okay, there's some kind of amplifier in there driving the displacement. 137 00:15:04,120 --> 00:15:09,520 We don't know what it is, but we can believe that that would hold the sense of sight. What's that got to do with the other problem? 138 00:15:09,760 --> 00:15:18,220 The frequency selectivity and the way to understand that is to simply think of an example of a natural system that has a natural frequency. 139 00:15:18,230 --> 00:15:25,330 So a good example of this is a child in a playground swing. So first, imagine that the child is sitting there passively. 140 00:15:25,720 --> 00:15:29,910 The swing has a natural frequency that's given by the likes of the wrote the mouse to the child itself. 141 00:15:30,610 --> 00:15:35,410 And now the parent comes along and pushes this way. It's very easy to push that swing and it's not for frequency. 142 00:15:36,130 --> 00:15:40,780 If you work harder, you can push the swing of frequencies other than the natural frequency. 143 00:15:41,380 --> 00:15:47,500 And so this system where the the driver is outside the system is a fairly politician system. 144 00:15:47,500 --> 00:15:55,049 A number of frequencies could be sustained. But now remove the mother from the picture to remember your own experience as a child on the playground. 145 00:15:55,050 --> 00:15:58,890 Swing all around when you kick your legs in time with this. 146 00:15:59,040 --> 00:16:05,280 You remember what happened. The amplitude of the swing rises for memory dramatically, and when you kick your legs out the time of the swing, 147 00:16:05,400 --> 00:16:10,150 it stops abruptly when the swing is driven by an internal amplifier. 148 00:16:10,170 --> 00:16:13,290 The child is a much more finely tuned system. 149 00:16:13,710 --> 00:16:18,860 And that was the basic idea. Atomico. Now in the 1980s, 150 00:16:18,860 --> 00:16:27,410 it became possible for the first time to measure with great precision by solar membrane displacements when signs are presented to the solar membrane, 151 00:16:27,440 --> 00:16:35,420 a living out of them. And this is what we see. So that's just the same, Tom, that Rebecca Transposon predicted, but it's quite different. 152 00:16:36,320 --> 00:16:42,360 In reality, there's a much bigger displacement, and that's the amplification, but also there's a much narrower response. 153 00:16:42,360 --> 00:16:47,680 So that's the frequency selectivity. And if I showed you what 20 kilohertz would look like, that would also be like this one. 154 00:16:47,690 --> 00:16:52,890 Would it be white on it? Inside its internal amplifier is responsible. 155 00:16:54,290 --> 00:16:59,930 And that's the evidence for it. So there's an existing amplifier within the organ of Cotai that increases the displacement 156 00:17:00,290 --> 00:17:04,639 of the membrane like this to make soft sounds audible and provide excellent frequency. 157 00:17:04,640 --> 00:17:09,270 So activity. And that's exactly like the actor chart this way. 158 00:17:11,100 --> 00:17:17,750 Now you can look at this data another way and make a plot of the bus with a membrane displacement nanometres. 159 00:17:18,150 --> 00:17:21,510 Thus the loudness of the sound this way. 160 00:17:22,140 --> 00:17:28,530 So loud sounds mean. Lots of displacement that's up here. And soft sounds mean, much less displacement which is done here. 161 00:17:29,340 --> 00:17:34,680 And this is the data from going back to try and extrapolation down to self to sounds. 162 00:17:35,130 --> 00:17:43,680 And this is what's actually said in modern measurements. So it's very different from back office predictions and observations. 163 00:17:44,630 --> 00:17:48,140 And so you could ask should because package have won the Nobel Prize. 164 00:17:50,170 --> 00:17:55,360 To answer that. The first answer that was actually given by a guinea pig, literally a guinea pig. 165 00:17:55,840 --> 00:17:58,960 If you take this this data, it's taken on living guinea pigs. 166 00:17:59,410 --> 00:18:03,730 That species have a particularly easy cochlea to study. 167 00:18:05,050 --> 00:18:09,790 And what happens is this is a very unpleasant operation, Cricket. You have your head opened up. 168 00:18:10,240 --> 00:18:13,330 You're monitoring the motion, the bustle, the membrane, the sounds being played to you. 169 00:18:13,330 --> 00:18:15,640 And sometimes during this operation, the guinea pig dies. 170 00:18:17,100 --> 00:18:24,240 And if the guinea pig dies and you continue to take nature, what happens is the data falls right down onto this line about because you. 171 00:18:27,120 --> 00:18:28,820 So before she got the results, 172 00:18:28,840 --> 00:18:36,969 he did because he performed them on a human cadaver at their cochlear is entirely different to a living call, to a dead copula. 173 00:18:36,970 --> 00:18:40,870 It's like a passive child on the slate. They didn't. Cochlear, as a child, pointed his legs. 174 00:18:41,980 --> 00:18:48,130 The dramatic difference. And so going back to China was a part of physics and definitely deserves a Nobel Prize. 175 00:18:50,620 --> 00:18:57,470 So now what's causing this amplification? And so this is a high magnet edge over basilar membrane. 176 00:18:57,770 --> 00:19:01,850 And these are in rehearsals and these are three rows of outer hazards. 177 00:19:02,750 --> 00:19:09,470 The inner Hassan is about 3500 per ear or afferent highly afferent signals are going through the brain. 178 00:19:10,220 --> 00:19:15,110 The outer vessels, on the other hand, of which there are far more, are rather sparsely innervated. 179 00:19:16,200 --> 00:19:21,419 And this is a typical house. It's another one in this case, study, microbes all about five microns wide. 180 00:19:21,420 --> 00:19:30,909 And you can see the cilia atop it. If you look at a bit more detail, each of these little has this 500 nanometres across. 181 00:19:30,910 --> 00:19:39,670 So that's about a 20th or so the thickness of a hole in your head. And they're joined by fibrous actin strands that are just a few nanometres across. 182 00:19:40,570 --> 00:19:45,010 And when the cell deflected due to the cell causing the basilar membrane to move. 183 00:19:46,420 --> 00:19:50,050 This tip links open truck doors and the walls of the cells. 184 00:19:50,740 --> 00:19:54,520 The potassium rich solution of the complex flows into the cell. 185 00:19:55,430 --> 00:20:00,830 Cells are like batteries are highly polarised. And so the arrival of this car, the polarises, the cell, 186 00:20:01,460 --> 00:20:08,960 and that triggers a sequence of complex chemical steps of at least neurotransmitters at the base of the cell, which pass through the auditory nerve. 187 00:20:09,380 --> 00:20:16,550 And we hear sound. Now both in and hassell's work in that way. 188 00:20:18,950 --> 00:20:28,460 But if these new cells are connected to our brain on a conveying sound to host to it so we can see this with the following movie. 189 00:20:29,150 --> 00:20:32,180 So this is on our side. It's about 70 microns long. 190 00:20:33,280 --> 00:20:39,810 So we take a microphone. We're going to play music through the microphone, the microphone and turn that sound into a cup. 191 00:20:40,710 --> 00:20:45,540 And this current will be modulated by the tempo and the amplitude of the music. 192 00:20:45,900 --> 00:20:51,840 And then we take that current in this and place it into this electrode and the electron goes into the sun. 193 00:20:54,570 --> 00:20:59,010 So now when we start playing, let's watch what happens to the cell. Watch the music starts. 194 00:20:59,010 --> 00:21:07,030 So the current starts. To bring the popular pop, rock and pop, pop, pop. 195 00:21:10,000 --> 00:21:15,330 A lot of the time. 196 00:21:26,230 --> 00:21:32,320 So remember this the next time you dance to the music through. Sure, the Scots like at 16,000 households and it's reality. 197 00:21:34,060 --> 00:21:39,610 So what's happening here is the cars going into the south. The sun is losing its polarisation. 198 00:21:39,610 --> 00:21:43,360 As it polarises, it returns to its natural light. The change length. 199 00:21:43,360 --> 00:21:51,610 Like there's a couple of microns. So the sequence of events as the muscle membrane is displaced due to the presence of sound. 200 00:21:52,570 --> 00:21:57,460 The Protocell flows into the other hair cells, which then contract just like in the movie, 201 00:21:58,180 --> 00:22:00,639 because the other half cells are connected to the base of the membrane. 202 00:22:00,640 --> 00:22:07,450 That increases the displacement of the rest of the membrane so that even the softest sounds will cause Newcastle Centre to be deflected. 203 00:22:08,050 --> 00:22:12,130 Current flows into that neurotransmitters are released at the base, other parts of the brain. 204 00:22:16,020 --> 00:22:23,610 And so to summarise from the motion of our molecules to the vibration of a temperate membrane, 205 00:22:24,300 --> 00:22:33,960 the transmission of vibrations through the oscillators to the piston, like action of the statements to the displacement of the fluids and the sky, 206 00:22:34,890 --> 00:22:40,950 to the reflection of the cilia atop the hearse, others to the opening of truck doors for the floor of the custom car, 207 00:22:40,950 --> 00:22:45,959 and into those cells to a sequence of complex chemical steps that produce 208 00:22:45,960 --> 00:22:49,830 neurotransmitters that produce for countries on the order of the passes to the brain. 209 00:22:50,430 --> 00:22:54,750 It's a sequence of events that have given rise to an auditory perception. 210 00:23:06,070 --> 00:23:10,430 So that's how we hear. Here are five reasons why we don't waste it. 211 00:23:11,420 --> 00:23:18,710 The first is genetic. The second is infections, for example, bacterial meningitis or rubella. 212 00:23:19,900 --> 00:23:22,980 The third is a Q to a chronic exposure to loud sound. 213 00:23:22,990 --> 00:23:29,140 If sound is loud enough, it can produce enormous amounts of vibrational energy and can literally snot herself. 214 00:23:31,400 --> 00:23:40,040 Force causes prescription drugs, certain lots of toxics used in antibiotics and certain chemotherapeutic agents as well. 215 00:23:40,700 --> 00:23:47,570 And the first is hearing loss as we age, which affects most people to some degree more than 10% of our citizens. 216 00:23:48,080 --> 00:23:53,270 And very poorly indeed. And it severely interferes with their normal functions of life. 217 00:23:56,970 --> 00:24:01,410 Now the main types of variables are to the first is called conductive hearing 218 00:24:01,410 --> 00:24:06,600 loss the rarer and it involves the also claims being damaged in some way. 219 00:24:06,670 --> 00:24:10,640 Now the also claims of mechanical. And so you can repair them with surgery. 220 00:24:11,950 --> 00:24:14,770 Most hearing loss, however, is sensorineural. 221 00:24:15,220 --> 00:24:21,550 Sometimes when you see an audiologist who tell you you have nerve deafness, this is not true and nothing wrong with your nerve. 222 00:24:21,580 --> 00:24:27,070 The problem is that your hair cells are not that. Now as we age, we lose vessels. 223 00:24:27,370 --> 00:24:30,999 And in the vast majority of cases, as we age, we lose some of our houses. 224 00:24:31,000 --> 00:24:36,460 And so we lose some of our ability to transduced mechanical energy into electricity. 225 00:24:37,480 --> 00:24:43,810 And the solution to that is a hearing aid. Hearing aid to make sounds loud when a child is loud. 226 00:24:44,350 --> 00:24:49,090 That means that the stapes will move more vigorously. And so more energy will be placed into the bone. 227 00:24:49,180 --> 00:24:49,480 Other. 228 00:24:50,610 --> 00:24:59,070 So even though there's less to transduced that energy, the combination of more energy and less transduction cancel out and you can restore hearing. 229 00:24:59,310 --> 00:25:04,950 It's a very, very effective solution for most people with hearing loss and dramatically changes people's lives. 230 00:25:05,100 --> 00:25:08,880 Unfortunately, there's an enormous stigma associated with wearing hearing aids. 231 00:25:10,970 --> 00:25:18,120 However, 4% of all journalists. The number of households is dramatically reduced or is even absent. 232 00:25:18,990 --> 00:25:27,090 And in those cases, it doesn't matter how loud the signs are, the hearing aid will not help at all because there's no transduction occurring. 233 00:25:28,490 --> 00:25:33,590 And it's in those cases that the cochlear implant is a possible solution. 234 00:25:35,730 --> 00:25:42,000 So it might surprise you to know. The first cochlear implant was developed a couple of hundred years ago. 235 00:25:43,240 --> 00:25:48,930 But this guy, voter and of course, voter, had invented the bachelor, invented battery. 236 00:25:48,940 --> 00:25:52,330 Let's try it out. So let me tell you what he did. 237 00:25:53,050 --> 00:25:59,380 Both are close to metallic probes and both is connected to the ends of the 250 volt battery. 238 00:25:59,680 --> 00:26:03,820 And observe that at the moment when the circuit was completed, I received a shock in the head. 239 00:26:04,750 --> 00:26:09,250 So moments after, I began to hear a sound of other noise in the areas which I cannot well define, 240 00:26:09,610 --> 00:26:14,380 it was a kind of a crackling with shocks, as if some post or tenacious matter had reported. 241 00:26:15,920 --> 00:26:18,430 Notice how beautifully they wrote in those days? 242 00:26:20,920 --> 00:26:29,050 He went on to say, the disturbing sensation, which I believe might be dangerous because of the information, the painting, the experiment. 243 00:26:31,960 --> 00:26:35,290 And if you're saying I just made that up, you can check it for yourself. 244 00:26:35,290 --> 00:26:40,780 So that's the of it is actually true. A wonderful example of experimental physics. 245 00:26:42,520 --> 00:26:50,620 Okay. So now let's move 200 years forward to the very end of the last century, the modern cochlear implant. 246 00:26:51,010 --> 00:26:56,410 So the most important thing to remember first about a cochlear implant is it's not a hearing and it does not make sounds loud. 247 00:26:56,470 --> 00:27:03,910 It's got nothing to do with that at all. But a cochlear implant is going to do is replace the naturally occurring transduction 248 00:27:03,910 --> 00:27:08,140 of the muscles by providing electricity that can go directly to the auditory dog. 249 00:27:08,680 --> 00:27:12,470 And that's what it is. So I've got one on another. 250 00:27:12,620 --> 00:27:17,480 And they had a set. Can you say set? But my left painter. 251 00:27:18,590 --> 00:27:26,870 I'll take it up so you can get a look. So this is a cochlear implant and obviously it's very hard for somebody to say it for her. 252 00:27:27,140 --> 00:27:30,350 And of course, the longer I keep this off, the more I can't hear what I'm saying. 253 00:27:30,950 --> 00:27:36,890 And so I have to put it back on in a second. But what I'll do now is talk you through the different parts of this device. 254 00:27:39,740 --> 00:27:43,190 So we began with a microphone and that bit, it's like hearing it. 255 00:27:45,890 --> 00:27:52,340 So that's the very front of my voice. And that microphone, of course, is going to transformed into an electrical signal. 256 00:27:53,330 --> 00:28:00,350 And then the second bit is a series of bypass filters and ac, ac integrated circuit, 257 00:28:00,350 --> 00:28:04,700 which is just a silicon chip which you consider to be a computer without an operating system. 258 00:28:05,720 --> 00:28:13,250 And what that's going to do is digitise and sort the sounds in terms of amplitude and in terms of time and in terms of frequency. 259 00:28:15,280 --> 00:28:16,660 And then the next thing that happens. 260 00:28:18,100 --> 00:28:28,210 And that these posters come out of this I and they're sent along the wall to the antenna, which is that thing which in this case is above the left. 261 00:28:28,540 --> 00:28:31,960 My case said it's wrapped around my head. And if you want to know where that is, you can ask it. 262 00:28:31,970 --> 00:28:35,970 Yeah. And so we'll see what things they attend to. 263 00:28:35,970 --> 00:28:42,780 We can now take this right away, very much like that. Right away with all of that digital information, they can pass it through the intact set. 264 00:28:44,370 --> 00:28:52,200 And pick it up at a receiver inside the second here, which is in the mastoid bone, it's about the size of a postage stamp. 265 00:28:52,770 --> 00:28:59,580 And what that thing is going to do is read all that information and turn it into analogue information about his pulses. 266 00:29:00,150 --> 00:29:08,850 And this post is going to pass along electrodes, of which there are many in the cochlear implant, and only one is shown in this picture in right here. 267 00:29:10,400 --> 00:29:16,969 It goes right down into the cochlear. Now the cooker is not literally to the side in here. 268 00:29:16,970 --> 00:29:27,760 It's actually towards the eye. And then the electrical pulses are producing electric fields which are picked up by the auditory nerve. 269 00:29:28,090 --> 00:29:35,960 And that signal that pulses to the brain. And the probe that recognises the signals asset. 270 00:29:36,780 --> 00:29:40,260 And I should say that in this picture the brain is not to scan. 271 00:29:44,440 --> 00:29:47,740 So here again is a schematic of a cochlear implant. 272 00:29:48,250 --> 00:29:51,440 That's the microphone, the speech processor, the transmitter. 273 00:29:51,460 --> 00:29:57,040 That's the skin. And under the skin as a receiver and a stimulator followed by electrodes. 274 00:29:58,630 --> 00:30:01,750 And so the natural hair and your side. 275 00:30:01,750 --> 00:30:10,270 The first part of this talk, you know, high frequency sound stimulates the cochlea and auditory base and low frequency sound stimulates at the apex. 276 00:30:12,220 --> 00:30:16,750 And so the idea of the cochlear implant is it's going to exploit that natural physiology. 277 00:30:17,740 --> 00:30:21,010 What we're going to do is spread electrodes along the cochlea, 278 00:30:21,280 --> 00:30:25,870 and individual electrodes will convey a certain range of frequencies to that part of the cochlear, 279 00:30:25,870 --> 00:30:30,040 which naturally responds to that frequency in our normal physiology. 280 00:30:33,440 --> 00:30:39,250 And so the strange process is continually measuring salt in the sound by pitch and by loudness. 281 00:30:40,860 --> 00:30:46,240 And then takes the high frequency solvents and sends them to electrodes that are right at the cochlear base. 282 00:30:46,540 --> 00:30:51,719 As low frequency sounds go to electrodes that call up 35 millimetres almost to the apex. 283 00:30:51,720 --> 00:30:56,040 So as close as you can get to that. That's the basic idea. 284 00:30:57,840 --> 00:31:04,110 Now this is a modern cochlear implant multi electrode and the scar, 285 00:31:04,110 --> 00:31:10,829 the timpani and light grey and actually auditory nerve and modernists and actually grey rectangles is an 286 00:31:10,830 --> 00:31:16,860 electrode pair and this flash or pulse is when the electrode is actually passed through an electrical signal. 287 00:31:19,390 --> 00:31:25,270 And in my device and in most of the other devices we pass the other trade-off around 20,000 times a second. 288 00:31:28,510 --> 00:31:34,720 Now cochlear implants? Well, the very first ones in the modern modern times through 1980. 289 00:31:36,450 --> 00:31:40,830 Over the course of two years, that performance improved dramatically. 290 00:31:41,640 --> 00:31:46,020 And so this is perception and patience versus time and type of device. 291 00:31:46,920 --> 00:31:51,690 In 1983, corporation developed a single electrode cochlear implant. 292 00:31:52,380 --> 00:32:01,320 What this did was enable patients to perceive sound, but not to comprehend it because there was no information about pitch. 293 00:32:03,530 --> 00:32:11,600 Subsequently these multi electrode devices were developed by Vipit and slowly with time were improved. 294 00:32:11,720 --> 00:32:14,510 So these are different manufacturers in yellow and in blue. 295 00:32:16,380 --> 00:32:22,050 Now using appropriate speech coding strategies, which means the way in which the information is presented to the auditory dog. 296 00:32:22,830 --> 00:32:32,459 By the late 1990s, it was possible in the best cases for a patient to perhaps understand 80% of the sounds that they were hearing 297 00:32:32,460 --> 00:32:39,120 as English and to translate that into words that they could repeat to the audiologist and get it correct. 298 00:32:40,140 --> 00:32:47,100 So that was a dramatic improvement. So 2001, I decided I would look into getting a cochlear implant myself. 299 00:32:47,820 --> 00:32:53,340 I delayed until then because I'd heard that although these devices in the best cases produced a very good result, 300 00:32:53,370 --> 00:32:56,250 there were many, many cases where they didn't produce a very good result at all. 301 00:32:58,860 --> 00:33:07,860 And the reason that 2001 was the moment that I decided to get the implant was because I was at a conference at Caltech and a good friend 302 00:33:07,860 --> 00:33:14,880 of mine undressed one out whose a kicked landscapes there is funny that I was attending the conference with me during a coffee break. 303 00:33:15,630 --> 00:33:23,440 He told me that his brother in law had an implant and his brother was similar age to me and Andress was doing really well with the implant. 304 00:33:24,200 --> 00:33:31,690 And so I decided to learn more about the device at that point. So first, let me tell you who can have a cochlear implant. 305 00:33:31,720 --> 00:33:38,290 Now, this slide is written for the United States audience, but in fact, it's not so very different in the U.K. 306 00:33:38,290 --> 00:33:46,279 I'll talk about small differences as we come along. So the first thing is you have to sort people in terms of, oh, you're an adult, your child. 307 00:33:46,280 --> 00:33:50,240 So let's talk first about adults. That means over the age of 18 in the U.S. 308 00:33:51,850 --> 00:33:57,160 But there's no limitation, by the way, with this technology. You could be 90 to benefit from a cochlear implant. 309 00:33:58,170 --> 00:34:01,770 So you need to have bilateral moderate to profound sensorineural hearing loss. 310 00:34:02,970 --> 00:34:07,620 You need to demonstrate those benefit from the state of the art hearing aids of the six month trial. 311 00:34:08,010 --> 00:34:11,280 Approximately a million citizens in the U.S. qualify. 312 00:34:12,130 --> 00:34:15,190 But only 71,000 had a quote. For the last time, 313 00:34:15,190 --> 00:34:22,240 the Federal Data Administration gave the details of how many people had implants in the U.S. That number is now unofficially about 100,000. 314 00:34:22,780 --> 00:34:29,080 That's much less than the number of people that actually need a cochlear implant and about 10% of the people that need it, 315 00:34:29,410 --> 00:34:32,830 more children are represented. I don't send number. 316 00:34:34,460 --> 00:34:40,750 Now you need to be psychologically suitable. At the time I applied to have the cochlear implant. 317 00:34:40,750 --> 00:34:47,550 I'm lip reading and I was interviewed by the doctor. And the doctor said, no psychotics. 318 00:34:48,120 --> 00:34:54,510 But literally I thought he said, no physicists. Fortunately, no. 319 00:34:54,970 --> 00:35:02,280 I think you mustn't have any anatomic contraindication, for example, bony occlusions in your cochlea because then you couldn't put the electrodes in. 320 00:35:03,430 --> 00:35:10,030 And then if you pass these tests, then you do CT scans and memorise, and then you get to choose what you would like to have implanted. 321 00:35:10,480 --> 00:35:17,450 And there are three main choices. That's Cochlear. But an Australian piano company medal in Europe and clarinet in the US. 322 00:35:17,470 --> 00:35:21,670 I chose the latter. Each of these manufacturers would tell you their device is by far the best. 323 00:35:21,910 --> 00:35:26,920 The truth is they all have very similar performance and it's the patient that's allowed to scribble and the outcome. 324 00:35:27,800 --> 00:35:32,780 And then you have to wait for surgery. And that can be many, many months. And finally, the surgery day arrives. 325 00:35:33,680 --> 00:35:39,680 And this is the surgery. This is the playoffs to me. And opening up the wrong window, the electrode placed into the scar, 326 00:35:39,680 --> 00:35:45,380 the temple there and a postage stamp request is covered in the mastoid bone to hold the receiver stimulator. 327 00:35:45,620 --> 00:35:51,560 And the magnet is a major surgery. 3 to 4 hours under general anaesthesia should be done at a good medical school. 328 00:35:56,410 --> 00:36:01,650 Now what happens afterwards? Well, post-operative complication rate is quite low. 329 00:36:01,660 --> 00:36:06,430 It's less than 5%. Most common problems I listed. 330 00:36:06,440 --> 00:36:09,840 The first is wound infection breakdown that's usually easily recoverable. 331 00:36:10,560 --> 00:36:19,320 The second is rare, but devastating. And that spatial nerve injury classically occurs about a millimetre from the first year of the patient. 332 00:36:19,440 --> 00:36:26,700 This transect does not regrow. This means permanent facial paralysis, which is a tragedy for the patient. 333 00:36:27,120 --> 00:36:33,680 And it's a tragedy for the surgeon as well. The next thing that could happen is vertigo. 334 00:36:34,370 --> 00:36:41,090 Vertigo, because the organs of balance and the bony labyrinth, along with the organ of hearing that usually also resolves. 335 00:36:42,300 --> 00:36:46,950 And then there is the possibility of a traditional hardware failure, which many experimentalists familiar with. 336 00:36:47,220 --> 00:36:50,520 We just try it out and put a new device in and that usually works very well. 337 00:36:50,880 --> 00:36:56,700 I've got people that have had four devices in project, including one of my students that is doing really well now, 338 00:36:56,700 --> 00:36:58,560 but he didn't really like having to have the first three. 339 00:37:00,000 --> 00:37:05,270 And then the other thing you have to do for the rest of your life is avoid MRI because you haven't like it. 340 00:37:06,660 --> 00:37:11,620 And the purpose of that magnet is to hold the transmitter outside the head in close proximity to 341 00:37:11,620 --> 00:37:16,620 the receiver stimulator to ensure an effective and efficient transmission of the information. 342 00:37:17,370 --> 00:37:23,230 And then you have to wait eight weeks for the one to hear. Before you can actually have the device turned off. 343 00:37:24,010 --> 00:37:29,560 And during that time, you wonder how to pay the medical bill, at least in the U.S. 344 00:37:30,910 --> 00:37:39,400 And the reason why you wonder is because this is not cheap. The cost in the U.S. is about $100,000 from here. 345 00:37:40,510 --> 00:37:44,020 That includes everything from the surgery to the post-operative care. 346 00:37:45,190 --> 00:37:48,880 Medicare and Medicaid in the U.S. pay total a partial cost, depending on state. 347 00:37:49,600 --> 00:37:55,569 Some private insurers refuse to cover this device. But over the last ten years, that's radically changed. 348 00:37:55,570 --> 00:37:59,200 And now only 10% to 90% now cover the device. 349 00:37:59,230 --> 00:38:02,200 There's been a big shift in the last four years, which is very welcome. 350 00:38:03,480 --> 00:38:11,130 This is a quote, the reimbursement that wasn't forced hospitals to close programs due to the cost of subsidising the input. 351 00:38:12,280 --> 00:38:15,610 Other hospitals ration services by putting children on waiting lists. 352 00:38:16,120 --> 00:38:17,470 These are the current statistics. 353 00:38:17,830 --> 00:38:27,430 In the US, only about 6% of eligible adults in Western Europe have socialised medicine about twice as doing twice as well. 354 00:38:28,000 --> 00:38:31,840 But that still means that most people would benefit from a cochlear implant to not have. 355 00:38:33,990 --> 00:38:36,980 And you know, this cost looks like a big number here. 356 00:38:36,990 --> 00:38:43,830 But the U.S. government themselves estimates that the cost of going through life just for the hearing world is about $1,000,000 per person. 357 00:38:44,700 --> 00:38:50,489 And that's just the economic cost. Just imagine the personal cost of going through life stuff in a harrowing world. 358 00:38:50,490 --> 00:38:55,410 Incredibly difficult. Another quote. 359 00:38:57,230 --> 00:39:00,800 Ultimately, this is about the way society is hearing. Being deaf is going to kill you. 360 00:39:01,040 --> 00:39:05,750 So some insurance companies see this as necessary and there are still issues now, even with Obamacare. 361 00:39:06,380 --> 00:39:13,790 Some states still same cochlear implant programs closing because the reimbursement levels are not sufficient to support the cost. 362 00:39:15,810 --> 00:39:20,460 So I was one of the lucky ones because the cost of my implant was covered by insurance through Purdue University at the time. 363 00:39:20,930 --> 00:39:25,710 That was the first person to actually receive that coverage. And at the time I was denied coverage. 364 00:39:26,630 --> 00:39:32,300 But then they changed their mind. Since then, several more people have been able to get a cochlear implant as well. 365 00:39:33,750 --> 00:39:41,070 And so finally, about eight weeks after we have had the operation, it's ready to actually turn on the device. 366 00:39:42,210 --> 00:39:48,120 And in my case, the surgery was at the Royal Hospital for Children, which was one of the major centres in the U.S. the cochlear implants, 367 00:39:48,120 --> 00:39:53,790 part of Indiana University Medical College, and a really superb place for the really gifted surgeon. 368 00:39:54,740 --> 00:40:02,990 And the operation had been at the beginning of November. And we hope to go home to Europe, to London and to the Middle East. 369 00:40:03,410 --> 00:40:08,810 Danielle It's wrong to self-harm and as at Christmas and New Year and we hope that they would say someone that could hear it. 370 00:40:09,740 --> 00:40:13,370 But unfortunately, this scheduled activation date was January. 371 00:40:13,880 --> 00:40:19,310 So we're very, very disappointed. But then four days before we would get on a plane to come home for Christmas. 372 00:40:20,360 --> 00:40:25,610 Danielle had a phone call from the hospital, said there's been a cancellation and can't even come down the next day to be activated. 373 00:40:25,700 --> 00:40:33,620 So, of course, she had surgery about it. So the next day I go down to Indianapolis and we walk into a very high tech audiology suite. 374 00:40:34,100 --> 00:40:41,570 Batteries of computers and lots of test kits. And you sit down, you're plugged into a PC and various tests performed upon you. 375 00:40:41,840 --> 00:40:46,380 And I say P.C. advisedly, because I'm not compatible. And this doesn't this crushes in head. 376 00:40:47,990 --> 00:40:53,840 I look like that anyway. So you hear nothing during this time at all. 377 00:40:55,800 --> 00:41:00,320 After about almost an hour of this, the audiologist turned to me and I was lip reading still, 378 00:41:00,330 --> 00:41:03,659 and she said, We're going to turn this device on about five more minutes. 379 00:41:03,660 --> 00:41:07,480 So please understand that you've been dead for 12 years. 380 00:41:07,500 --> 00:41:09,840 The chances that you will hear anything are quite low. 381 00:41:10,850 --> 00:41:15,319 If you're lucky, you'll be able to hear soft sounds, but you won't be able to recognise the speech. 382 00:41:15,320 --> 00:41:19,130 But if you were really, really lucky, you might be able to actually understand speech right away. 383 00:41:20,270 --> 00:41:26,530 So she then turned back to the APC and continued to perform tests. And after about another three or 4 minutes, I became impatient. 384 00:41:26,540 --> 00:41:29,510 I turned to her and I said, Have you tried this device on yet? 385 00:41:30,230 --> 00:41:34,219 And before I got to the end of that sentence, I realised I was hearing my own voice through. 386 00:41:34,220 --> 00:41:37,460 My own is for the first time in 12 years. 387 00:41:39,850 --> 00:41:47,530 Better yet, that evening I got back home to Peru and hurt my wife twice for the first time in 12 years. 388 00:41:48,430 --> 00:41:55,270 And because my daughter was born shortly after I became deaf, I heard my daughter's voice for the very first time. 389 00:41:56,070 --> 00:42:00,600 And there are really no words in the English language to convey to you how marvellous that was. 390 00:42:01,200 --> 00:42:06,609 But this is the power of science and engineering. To improve the human condition. 391 00:42:06,610 --> 00:42:10,730 One of the great reasons to do it. So how does this device work? 392 00:42:11,570 --> 00:42:17,030 This is the kind of audiogram that many of you have had in your lives. This is loud sound here, substance here. 393 00:42:17,420 --> 00:42:24,440 And this is frequency, low frequencies in high frequencies. And this is the normal performance of a healthy adult. 394 00:42:25,460 --> 00:42:32,480 Having threshold around 20 decibels or so. This is both auditory performance before the implant. 395 00:42:33,200 --> 00:42:37,040 And what that means is if you stand on a runway or just about hear the jumbo jet. 396 00:42:39,050 --> 00:42:42,450 And this is six months after that commotion. It's a dramatic improvement. 397 00:42:42,990 --> 00:42:50,310 This is the kind of performance that someone in the early forties would have if they experienced a normal amount of hearing loss. 398 00:42:50,590 --> 00:43:02,150 So this is nothing unusual. So these are speech tests, different types performed before the operation, six months after the operation. 399 00:43:03,380 --> 00:43:08,570 And you can see in some cases I got 0% for the operation and 96% after the operation. 400 00:43:09,150 --> 00:43:13,370 But, you know, it's kind of embarrassing to be a physics professor. You had 0% in a test. 401 00:43:15,560 --> 00:43:21,620 But anyway, at the time 2003, these scores were considered to be exceptional. 402 00:43:21,710 --> 00:43:24,510 There were other examples of exceptional performance, but this was not typical. 403 00:43:25,470 --> 00:43:34,170 The good news is that today 75% raised the possibility that patients have studied the glasses and, you know, visual cues whatsoever. 404 00:43:34,170 --> 00:43:37,890 Just use the phone straight. So the question then becomes, why does this work? 405 00:43:38,490 --> 00:43:47,040 You saw we have 3500 households. This device y device has ten electrodes, of which two broke during the surgery. 406 00:43:47,040 --> 00:43:51,700 So I've got eight. I can understand you. So how can. 407 00:43:53,810 --> 00:44:00,500 The reason is because hearing doesn't end at the cuckoo perception, whether it's visual or auditory. 408 00:44:00,890 --> 00:44:04,850 It's a combination of top down and bottom up processing. 409 00:44:07,400 --> 00:44:12,830 It's really, really, really important to understand that sensory detail, the level of it, 410 00:44:12,950 --> 00:44:18,740 the distinctiveness of the object, playing a very big role in our recognition of the world around us. 411 00:44:19,280 --> 00:44:25,790 For example, if you see a huge grey animal in the distance, you don't need to know much detail to know it's an another. 412 00:44:27,310 --> 00:44:32,050 So I'd like to do is give you some exercises in perception. 413 00:44:33,590 --> 00:44:38,030 And so first, I want to show you a very famous person. 414 00:44:39,040 --> 00:44:40,620 Now, usually I give this talk at the States. 415 00:44:40,650 --> 00:44:47,710 I just say, verify this question because this is the U.K. I actually tell you, this is a very famous American person and it's a historical figure. 416 00:44:49,520 --> 00:44:54,590 And so this election is going to contain very few pixels. 417 00:44:56,070 --> 00:45:03,750 And so it will be difficult for you to use only bottom up information, just the information in those pixels to recognise who this person is. 418 00:45:05,030 --> 00:45:08,870 However, because I've told you that it's a famous American historical figure. 419 00:45:09,770 --> 00:45:12,770 You've also got Top Gun knowledge, which you can use. 420 00:45:13,640 --> 00:45:20,780 And in this particular exercise, what you will probably find is that the top down knowledge is enough to work with 421 00:45:20,810 --> 00:45:25,160 the minimum amount of bottom up information to reconstruct who this person is. 422 00:45:26,580 --> 00:45:32,470 So. Tell me if you recognise who this is. Marijuana. 423 00:45:33,670 --> 00:45:40,450 That's right. So for those that didn't get it. But this paucity of bottom up information, I'm going to add more information to you. 424 00:45:40,450 --> 00:45:50,600 And you gradually say they could come into the. Now the language equivalent of that would be a missing word in a well-known phrase. 425 00:45:50,690 --> 00:45:55,190 For example, I pledge allegiance to the flag of the United States of America. 426 00:45:55,730 --> 00:45:58,870 You do not have to know that red flag. That's obvious. 427 00:45:58,880 --> 00:46:04,220 Is the context that tells you. And so that's the top down, working with the information. 428 00:46:06,340 --> 00:46:10,390 And this is exactly how posting really deaf adults understand the world around them. 429 00:46:11,110 --> 00:46:13,810 This device is not capable of giving me every word that you say. 430 00:46:13,850 --> 00:46:19,750 It gives me a few words, and if I don't know the subject, I can backtrack over the last couple of sentences. 431 00:46:19,910 --> 00:46:23,650 Hope to understand something at the current centre to reconstruct the conversation. 432 00:46:24,370 --> 00:46:29,890 And although this takes time to learn, eventually it becomes very easy to do inventory. 433 00:46:32,720 --> 00:46:36,770 Now I'd like to take away your ability to use top down processing. 434 00:46:36,770 --> 00:46:40,970 So I want to give you another example. In this case, it's an object you've all seen before. 435 00:46:42,350 --> 00:46:46,510 But it's much less distinctive. They're much less familiar with it. 436 00:46:46,810 --> 00:46:53,110 I'm not going to give you any information about what it is ahead of time. So they're going to rely entirely on bottom up information. 437 00:46:54,080 --> 00:47:04,690 So tell me what this is. Good. So I'd add more information and more information, and it's gradually seen as coming into this, a rather famous picture. 438 00:47:05,620 --> 00:47:09,070 Now you see it, right? Disintegration of the Persistence of Memory by Salvador Dali. 439 00:47:11,790 --> 00:47:14,880 No. The audit trail. I don't know that. 440 00:47:15,810 --> 00:47:19,920 Would be missing words in a sentence or phrase you've never heard before. 441 00:47:21,550 --> 00:47:25,040 Or hearing a foreign language. Oh. 442 00:47:26,160 --> 00:47:28,890 Hearing language for the first time through a cochlear implant. 443 00:47:30,170 --> 00:47:34,910 And that's exactly the situation of dealing with it, of course, when they're given a cochlear implant. 444 00:47:34,940 --> 00:47:37,130 So for the adult post language, he does. 445 00:47:37,460 --> 00:47:46,760 Our challenge is to recognise that for the young child who's never experienced the auto audio world before, the challenge is to recognise the picture. 446 00:47:46,760 --> 00:47:47,930 That's much harder thing to do. 447 00:47:49,010 --> 00:47:57,270 And so the question then becomes, is the cochlear implant capable of providing enough information to help a child understand the world around? 448 00:47:58,670 --> 00:48:06,800 So this is a photograph of the word choice. This is frequency versus time and it's colour coded with white being the loudest sound. 449 00:48:07,580 --> 00:48:11,479 That's. Sure. This is the. And that's. 450 00:48:11,480 --> 00:48:21,720 That's at the end. Now if you replace frequency with electrode Doppler and look at what the implant sees, it sees that. 451 00:48:23,030 --> 00:48:26,680 So you can say they are similar, but are they similar enough? 452 00:48:28,900 --> 00:48:34,300 And so there's been a great deal of work on optimising cochlear implants to maximise speech perception. 453 00:48:34,750 --> 00:48:38,560 And so you can ask, what are the things that we've got to actually get right? Is there amplitude? 454 00:48:39,220 --> 00:48:44,710 Well, if I'm speaking relatively softly, relatively loudly, as long as you can hear me, you'll understand. 455 00:48:45,430 --> 00:48:49,640 Plentitude is not very important. How about the temple structure itself? 456 00:48:50,090 --> 00:48:54,230 They're all familiar with the idea that in the movie, old fashioned movie, the film runs slow. 457 00:48:54,470 --> 00:48:59,180 You'll start to see a series of still images instead of a continuous motion. 458 00:48:59,780 --> 00:49:03,800 And this would correlate here with the rate at which you post the order shoot up. 459 00:49:03,920 --> 00:49:10,749 It turns out that we composed the instrument so quickly you're always unaware of the pulsing, so as a continuous sound. 460 00:49:10,750 --> 00:49:12,770 And so the tempo structure was not important either. 461 00:49:13,520 --> 00:49:19,340 It turns out that the most important one is the number of locations that works, the stimulated and the places stimulation. 462 00:49:19,370 --> 00:49:24,920 This is what really matters. So this co-writes the pitch. So I'd like to give you an example of this. 463 00:49:26,480 --> 00:49:32,930 So I'm going to play for you a sentence in English. And this sentence is going to go through a single bound passcode. 464 00:49:33,090 --> 00:49:39,530 In other words, there'll be no frequency information whatsoever. And I'd like you to tell me what this sentence is. 465 00:49:43,710 --> 00:49:47,510 You didn't get it right. Okay. So now let's do the following. 466 00:49:47,510 --> 00:49:52,850 So that was by the way, that was one channel. Right. Well, so it's like one electrode and that's a bit like what Volt would have hoped. 467 00:49:55,580 --> 00:49:57,469 So now let's just try to channels. 468 00:49:57,470 --> 00:50:03,080 Now, two channels means that we're going to take two bypass motors, one for all the low frequencies, one for the high frequencies. 469 00:50:03,440 --> 00:50:07,129 So any more information, but not much. But tell me what this is. 470 00:50:07,130 --> 00:50:16,430 It's the same sentence in English, so probably it's not a different tune to the first one, but it probably was unintelligible. 471 00:50:16,790 --> 00:50:23,840 Right. Okay. So now let's go to four channels. So that's low, medium, low, medium, high, high again. 472 00:50:23,990 --> 00:50:30,800 Tell me if you recognise this. The same sentence. It's beginning to become words, right? 473 00:50:32,540 --> 00:50:35,630 To see the differences. Gradually building up is more like language. 474 00:50:37,090 --> 00:50:43,960 Right now. Let's go to right now. I should tell you how he did electronics, but I can understand this. 475 00:50:44,950 --> 00:50:49,680 So you tell me what this is. I think you can do it, Sir Charles. I would like to point out that. 476 00:50:50,950 --> 00:50:54,750 That's right. I like to play tennis. Right. So that's right. 477 00:50:55,720 --> 00:51:05,000 Now. Not too many of you didn't get it because you're not able to rely only on bottom up because there's not really enough good about. 478 00:51:05,210 --> 00:51:08,360 So only occasion if someone ever got it approximately correct. 479 00:51:09,380 --> 00:51:11,510 So now let me play for you the original. 480 00:51:13,070 --> 00:51:20,470 But before I play for you the original which I think you recognise, I should tell you that for me I never should have said exactly the same to you. 481 00:51:20,500 --> 00:51:25,590 It's not very different. I like to play tennis. 482 00:51:27,040 --> 00:51:31,990 You say no, you heard it right. You all understood original. But everyone understand the original preamble if you did. 483 00:51:32,710 --> 00:51:36,370 I'm just checking because I'm not sure how good the sound is. Because the sound as well. Right. 484 00:51:37,480 --> 00:51:44,470 Okay. So now. Now that you've heard the machine, you can use your top down processing. 485 00:51:45,500 --> 00:51:49,470 To reconstruct the much poorer childhood without trials. 486 00:51:50,420 --> 00:51:53,580 So can I listen to this again? I think to understand it now. 487 00:51:53,960 --> 00:51:57,860 I like to put the. It's dramatically different. 488 00:51:58,730 --> 00:52:00,500 So that's the power of top down processing. 489 00:52:01,160 --> 00:52:08,569 Now, you might be saying that it is in a world of eight channels, and so these voices are horribly robotic, but they actually are not. 490 00:52:08,570 --> 00:52:13,250 And the reason for that is because the brain, if a person would do that, remembers how sounds were before. 491 00:52:14,350 --> 00:52:17,319 And so the information I get in, which did sound horribly, rebuts it. 492 00:52:17,320 --> 00:52:20,650 When I first got by upload, the brain says, no, people don't sound like dialects. 493 00:52:21,520 --> 00:52:25,510 And so it puts memory plus memories of voices onto people. 494 00:52:25,840 --> 00:52:30,130 Now, most of the people I've never met. So I've given you all voices based on my relations. 495 00:52:32,500 --> 00:52:37,060 Yeah, but they're very nice voices. There literally no sources. That's okay. 496 00:52:37,360 --> 00:52:43,060 No, it's not surprising that it's not easy to work with so few channels and understand anything, and so it takes time. 497 00:52:43,530 --> 00:52:48,480 And so this is a quick plot of perception in adults who oppose literally death. 498 00:52:48,820 --> 00:52:52,660 And they had preoperative flair. They couldn't understand sentences. They got the implants. 499 00:52:53,050 --> 00:52:56,530 And over the course of six months, they gradually learnt how to use that implant. 500 00:52:56,890 --> 00:53:00,550 And so this is a lovely demonstration of the plasticity of the adult brain. 501 00:53:01,570 --> 00:53:07,930 But all of these adults were posted pretty tough. And so they used their and knowledge of language. 502 00:53:08,080 --> 00:53:12,390 So it's top down processing and it was powerful. What about the printing with the deaf children? 503 00:53:12,400 --> 00:53:14,230 This is where the device becomes controversial. 504 00:53:15,570 --> 00:53:20,670 And so this slide again is for the U.S. but very similar arguments apply in Western Europe and the U.K. 505 00:53:21,690 --> 00:53:30,000 So the first thing is that most of you probably know that people who live in the deaf community and who lead very fulfilling and productive lives. 506 00:53:31,800 --> 00:53:39,930 Emphasising. Sign language, but no auditory ordinary language or language that we use. 507 00:53:41,490 --> 00:53:50,100 In the 1990s in the United States, there was very strong opposition to paediatric implantation while there was neutrality to adult implantation. 508 00:53:50,100 --> 00:53:55,080 And the argument was that the implant delays a deaf child's acquisition of sign language, 509 00:53:55,470 --> 00:53:59,280 which is the deaf child's natural language and their assimilation into the deaf community. 510 00:54:00,840 --> 00:54:07,739 1991, the National Association for the Deaf, and there were similar statements in the UK and other countries as well deplored the 511 00:54:07,740 --> 00:54:12,930 FDA decision to approve paediatric implantation as being unsound scientifically, 512 00:54:13,140 --> 00:54:14,760 procedurally and ethically. 513 00:54:16,220 --> 00:54:23,630 However, within ten years the situation has changed and the deaf community now tends to regard implantation as a personal decision. 514 00:54:24,260 --> 00:54:30,440 The 2000 statement emphasised taking advantage of technological advances that have the potential to improve the 515 00:54:30,440 --> 00:54:37,610 quality of life for deaf and hard of hearing persons and strongly supports the development of the whole child. 516 00:54:37,610 --> 00:54:46,510 And of language and of literacy. So this is an example of one of the most cited studies of language development and show that with importance. 517 00:54:47,380 --> 00:54:50,770 And so the graph on the left shows language, age versus not. 518 00:54:51,660 --> 00:54:56,380 So hearing children at age 48 months have a language age 48 months. 519 00:54:57,190 --> 00:55:01,030 The children who are the data points here are children that cannot hear. 520 00:55:01,810 --> 00:55:06,740 And so that natural age is much greater than the language. 521 00:55:08,880 --> 00:55:14,370 And now these children are going to be implanted in the dark because of the children that receive the implant. 522 00:55:14,730 --> 00:55:21,510 The white circles of children will control them. They don't. And this is the extrapolation of what we would expect to see. 523 00:55:22,470 --> 00:55:27,610 And on the right. The data point said property play and the person to move afterwards. 524 00:55:27,610 --> 00:55:33,320 Other children have been implanted. And this is their projected performance if they hadn't been employed. 525 00:55:34,240 --> 00:55:37,620 And so to quote from the paper, despite a large amount of individual variability, 526 00:55:37,620 --> 00:55:44,190 the best performers have been plucky group seem to be developing an all linguistic system based largely on auditory input from the cochlear implant. 527 00:55:44,460 --> 00:55:50,400 And that is a truly remarkable result. And it's perhaps the most joyful side of this talk. 528 00:55:51,450 --> 00:55:53,070 Now, cochlear implants are not perfect. 529 00:55:54,270 --> 00:56:01,260 One of the challenges is listening to music with that, because to hear music, one has to convey pitch very accurately. 530 00:56:01,620 --> 00:56:06,560 And so I'd like to play for you a piece of music, and you tell me what this is. 531 00:56:06,570 --> 00:56:09,750 This is how it sounds to me through a cochlear implant. 532 00:56:29,570 --> 00:56:33,469 Wasn't that us? Right. So now let me play the commissioner. 533 00:56:33,470 --> 00:56:37,250 Before I do, let me tell you the original and what you just heard sound exactly the same to me. 534 00:56:49,560 --> 00:56:52,590 So they were dramatically different. But you shouldn't say that. 535 00:56:52,590 --> 00:56:55,650 I therefore can't enjoy music as long as I know what the tune is. 536 00:56:55,920 --> 00:57:01,440 I can remember from the past, or if a lyric is there, I can reconstruct a very pleasant musical experience. 537 00:57:01,710 --> 00:57:03,900 And many countries and countries do exactly the same. 538 00:57:05,060 --> 00:57:10,460 So I'll just take two more minutes to talk about how the devices can be improved further and then wrap up. 539 00:57:11,180 --> 00:57:19,370 The first of them is that many, many people retain good hearing at very low frequencies, but lose hearing at high frequencies as they age. 540 00:57:20,000 --> 00:57:22,850 The low frequency hearing can be brought back with a hearing aid, 541 00:57:23,690 --> 00:57:27,230 and then the high frequency part can be brought back with the cochlear implant in the same area. 542 00:57:27,560 --> 00:57:33,000 A shorter cochlear implant is stimulating the base of the cochlear, and that's shown here. 543 00:57:33,000 --> 00:57:39,139 And in this case, a patient could understand nothing without ever hearing 51% with the cochlear implant only. 544 00:57:39,140 --> 00:57:44,810 But it was a great improvement and both are looking at once. It's a very easy way to improve the cochlear implant. 545 00:57:45,620 --> 00:57:49,130 The second is to have two cochlear implants instead of one. 546 00:57:49,160 --> 00:57:56,960 How do we know where sound comes from? When a sound is close, is produced closer to our left ear than are right here? 547 00:57:57,500 --> 00:57:59,750 It arrives in our left ear before our right to right, 548 00:57:59,780 --> 00:58:06,710 then passes from both Cochlear on long delay lines to common neurones in the medial superior olive. 549 00:58:07,280 --> 00:58:15,229 When signals arrive at a common neurone in synchrony that neurone files have a sound source that moves slightly to the right. 550 00:58:15,230 --> 00:58:21,379 The into all time delay is different, and so the signals arrive at a different common neurone in synchrony. 551 00:58:21,380 --> 00:58:26,600 A lot neurone flies. And in this way humans have built up the ability to tell the direction of sound to one degree. 552 00:58:26,960 --> 00:58:32,600 And the play is, however, with a cochlear implant, you're only getting a signal on one side. 553 00:58:32,600 --> 00:58:36,290 And so these neurones can never fire. And so you have no sense of direction. 554 00:58:36,860 --> 00:58:41,630 And so two cochlear implants can give a cochlear implant to your sense of direction. 555 00:58:41,960 --> 00:58:48,350 The precision is about 16 degrees. And this is an example of seven people that were lucky enough to have two cochlear implants. 556 00:58:48,740 --> 00:58:53,150 It's one of them off and say as the sound on your left or on your right, and they get it right half the time. 557 00:58:54,920 --> 00:58:58,880 But if they have both of them, they got over 100%. The sun is the hearing process. 558 00:58:59,660 --> 00:59:02,870 Once you get to cochlear implants, it's something else you can do as well. 559 00:59:03,170 --> 00:59:08,360 And that is understand speech. In a noisy environment, the world is full of noise environments. 560 00:59:08,900 --> 00:59:14,690 Her speech coming from the noises on the left, cochlear implant is on the left performance is poor. 561 00:59:15,620 --> 00:59:20,389 Move the noise source to the right. The shadow of the head blocks. 562 00:59:20,390 --> 00:59:23,870 This noise got to the cochlear implant so the person does better. 563 00:59:24,880 --> 00:59:31,390 But if you have two cochlear implants and the sound is from the front and the noises on the left or the right, 564 00:59:31,390 --> 00:59:35,890 the cochlear implant, you can score 100% in a test very similar to a hearing person. 565 00:59:38,890 --> 00:59:42,129 And as a second benefit as well, there are people who have a cochlear implant. 566 00:59:42,130 --> 00:59:46,840 They don't do very well with it. You had a second one and their understanding of the world around them is transformed. 567 00:59:49,280 --> 00:59:53,330 So the future of these devices, in addition to the two examples I just talked about, 568 00:59:53,900 --> 00:59:59,540 there is a lot of work ongoing on increasing the number of channels of stimulation along the auditory nerve. 569 01:00:00,500 --> 01:00:07,070 And that would lead to improved speech, performance and better future one stop, pitch and improve music appreciation. 570 01:00:07,820 --> 01:00:14,420 There's also a lot of work ongoing on reducing the power that these devices use so they can be fully implanted instead of being partially external. 571 01:00:15,080 --> 01:00:20,149 And cochlear implant performance in the end also depends on the health of the auditory nerve. 572 01:00:20,150 --> 01:00:24,860 And so there's a great deal of work ongoing on the regeneration of auditory nerve neurones. 573 01:00:27,510 --> 01:00:28,470 So to summarise. 574 01:00:28,830 --> 01:00:37,440 Implants have enabled the post-slavery deaf to hear and have provided sufficient information to support language development in children, 575 01:00:37,590 --> 01:00:42,560 which is a truly remarkable result. Implants were proud of speech recognition. 576 01:00:42,570 --> 01:00:47,430 We now know that exploiting telescopic organisation is the key to the implant success. 577 01:00:49,420 --> 01:00:55,150 The music and speech quality, including differentiating between man and female voices and accents. 578 01:00:56,140 --> 01:00:59,680 The cochlear implant does not yet provide enough information to allow. 579 01:00:59,680 --> 01:01:02,890 This is the natural frontier of cochlear implant research. 580 01:01:04,150 --> 01:01:12,610 But implants was the first prosthesis to successfully restore neural function and become a benchmark in biomedical engineering. 581 01:01:13,330 --> 01:01:15,290 So let me leave you with a couple of final thoughts. 582 01:01:15,310 --> 01:01:22,990 The first is that a cochlear implant is a truly wonderful example of a broad range of science and technologies, 583 01:01:22,990 --> 01:01:27,560 all of the disciplines listed here working together to improve the human condition. 584 01:01:27,580 --> 01:01:30,649 One of the great reasons to do science. Today. 585 01:01:30,650 --> 01:01:34,750 It has around a quarter of a million implants worldwide. 586 01:01:35,350 --> 01:01:36,729 And with the latest devices, 587 01:01:36,730 --> 01:01:46,690 about three quarters of post legally deaf adults can use the telephone and small children can hear their parents voices and learn to understand them, 588 01:01:46,690 --> 01:01:51,070 to hear their parents say to the child, I love you, and that's really priceless. 589 01:01:53,240 --> 01:02:01,190 Sometimes about a year or two. After I give this talk, I receive an email from someone that tells me that they have a cochlear implant. 590 01:02:01,190 --> 01:02:06,769 They're very happy with it. And what began their try to do cochlear implant was someone in the audience of this talk telling them about it. 591 01:02:06,770 --> 01:02:08,780 And that's the reason that I give this talk. 592 01:02:09,290 --> 01:02:16,850 So it is critically important that we work to make this technology more widely known and widely available to all our citizens. 593 01:02:18,300 --> 01:02:26,340 That's more than 20 million people in the world at this minute who would benefit from a cochlear implant in their lives would be transformed. 594 01:02:26,760 --> 01:02:29,819 And if we can make it possible for at least a few more of them to get it every 595 01:02:29,820 --> 01:02:34,140 day they can move to towards a happier and better world for those people. 596 01:02:35,100 --> 01:02:41,940 At a personal level. 11 years ago I had my hearing restored and it's enabled me to teach better and to do better research. 597 01:02:42,240 --> 01:02:47,220 And it also enabled me to hear my wife's voice for the first time in 12 years. 598 01:02:47,580 --> 01:02:51,030 And I do this voice for the very first time. Thank you very much.