Cochlear Implants
Chris Darwin
Cochlear Implant
1. Mic. 2.Lead 3. speech processor. 4 the transmitting coil 5. Transmitting coil sends the signals transdermally to the implanted receiver/stimulator via an FM radio signal. 6. The receiver stimulator 7. The electrodes along the array stimulate the remaining auditory nerve fibers in the cochlea. 8. auditory nerve
Cochlear implant 2
Shannon Implant Demo
Cochlear-implant simulation
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Simulated wav ef orm
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From herrick_uedamodel/script_demo1: best 6 of 16 channels, 250 Hz pulserate, 16 kHz sampling H/U filterbank
Simultaneous sentences
same Fo
difft Fo
difft Fo & VT
Shannon 4-channel implant simulation
summer
ignore
difft Fo
difft Fo & VT
Suitability for implant
Over 2 years of age
* Profound hearing loss in both ears
*
*
Does not benefit from conventional hearing aids
Has strong desire to communicate
“Deaf is not a disability, it’s a culture and a community”.???
1. Should a congenitally-deaf child of deaf parents be given a cochlear implant? 2. Should a congenitally-deaf child of normal-hearing parents be given a cochlear implant? (95% of early-onset children are born to hearing families) If given an implant, the child will get the sensation of hearing and may learn language. But is the child then removed from the Deaf world in which he/she would otherwise grow-up in and contribute to? Should the wishes of the parents or of the Deaf community be paramount? Misinformation from both sides???
Prevalence of hearing-loss in the U.K.
Hearing loss Prevalence Number of people (approximate) 8 million 2 million 500,000 150,000
25 dB or more (“mild”) 45 dB or more (“moderate”) 65 dB or more (“severe”) 90 dB or more (“profound”)
16% 4% 1% 0.3%
From NICE report p 4/5 and National Study of Hearing. My maths for the number of people (50million or so).
Cochlear Implants (UK) Adults
2600 2400 2200 2000
Cochlear Implants (UK) Children
2600 2400 2200 2000
Number of patients
Number of patients
1800 1600 1400 1200 1000 800 600 400 200 0
1800 1600 1400 1200 1000 800 600 400 200 0
'85 '87 '89 '91 '93 '95 '97 '99 '01 '03 '05
'85 '87 '89 '91 '93 '95 '97 '99 '01 '03 '05
Year
Year
Cochlear Implants (UK) Adults
300
Cochlear Implants (UK) Children
300
Number of patients per year No. implanted per year
200
Number of patients per year
'85 '87 '89 '91 '93 '95 '97 '99 '01 '03 '05
250
250
200
150
150
100
100
50
50
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0 '85 '87 '89 '91 '93 '95 '97 '99 '01 '03 '05
Year
Year
Costs of hearing-aids and implants in the U.K.
Total NHS audiology budget………………………approx. £60 million* Annual cost to NHS of hearing aids………………approx. £25 million* Annual cost to NHS of implants…………………...approx. £12 million** Average cost of supplying one hearing aid………approx. £90*
(average cost of aid alone = £40)
Total costs of implant per child patient…………...approx. £42 000** Total costs of implant per adult patient…………...approx. £29 000**
(includes fitting, rehabilitation and maintenance for twelve years)
* NICE report p.7 (1997 costs). Hearing aid costs is for aids/batteries **Summerfield and Marshall (1995) Cochlear Implantation in the UK 1990-1994 (in the Documents section of the library: Dept. Health 1995 Coc)
Effectiveness of implants
• Cochlear implantees require continual follow up. • Children, in particular, require a long period of rehabilitation
• to teach them to listen to the new sounds and
• to optimally tune the device. • All children who receive cochlear implants can learn to hear everyday sounds. • Most children are able • to hear conversation without lip-reading and • to use spoken language for everyday communication.
• Most implanted adults (>75%) are able to use the telephone
for conversation.
Arguments against implantation:
• Destroys any residual hearing in the ear.
• Not a „cure‟ for deafness.
• Can children actually learn language from an implant? … • … and some children gain no benefit from an implant. • Surgical operation under general anaesthetic. • Sign language is a proper language and is not English • There are Deaf schools and (one) Deaf university.
• Is Deaf culture a minority culture? Do UN declarations on
minorities apply?
Arguments for implantation:
• Implants do provide some hearing sensation. • Complication rate from surgery is extremely low.
• Some congenitally-deaf children can carry on a conversation.
• Best current medicine can offer for profoundly-deaf children.
• Deaf education may not be as good as normal-hearing education.
• Deaf children are more vulnerable to mental-health problems.*
* P Hindley (2002), paper at BNPA conference.
Progress…
• Effective number of channels is increasing • Music needs very good spectral resolution • Possible to double effective number of channels by alternating them spatially between the ears. • Experimental implants let the patient enjoy Beethoven again!
WWW resources
here
(outlining the background behind a new American documentary on Deaf culture and implants).
here (position statement of the National Association for the Deaf (USA) on cochlear implants).
here (Cochlear implant information and resources: squillions of links)
Reading material
Cochlear Implants: fundamentals & applications Graeme Clark AIP Press. Springer 2003 In University Library