Cochlear Implant Technology

December 2012

Unlike nontonal languages, music is highly dependent on accurate perception of pitch, a property related to the fundamental frequency of sound. Pitch functions as a basic building block of music and forms the foundation for musical melody, harmony, and scale. Impairments in pitch perception therefore translate into broad deficits for many different aspects of music perception. Pitch resolution is typically poor for CI users. Unlike normal hearing listeners who can detect a one percent or less difference for frequencies up to 4 kHz, CI users can only detect a 10 percent to 25 percent difference for frequencies up to 0.5 kHz and have much greater difficulties for frequencies over 0.5 kHz. (J Acoust Soc Am 2005;118[1]:338.) These pitch deficits can be largely attributed to the technological limitations of the device. Pitch is finely encoded in a normal cochlea by the place of stimulation along the cochlea (i.e., place-pitch), so that the apical end corresponds to lower pitches and the basal end to higher ones and the rate at which the auditory nerve fibers fire (i.e., rate-pitch) affects the pitch, or in other words, a faster rate elicits a higher pitch. These two mechanisms of pitch encoding in electric hearing, however, are severely degraded. Some 3,500 inner hairs cells convey finely tuned frequency information to the auditory nerve fibers based on their location along the cochlea in place-pitch for normal hearing. Comparatively, the implanted electrode array contains only eight to 24 electrodes that are meant to replace the frequency specificity of thousands of inner hair cells.  Full Story

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What's on the horizon for cochlear implants?

December 2011

Modern multi-electrode cochlear implants have restored partial hearing to more than 200,000 deaf people worldwide today. About half of these are children, with many of them having now developed language capabilities on par with their normal hearing peers.1 For cochlear implants to achieve this remarkable level of success, they not only had to compete against other devices such as tactile aids and hearing aids, they also had to overcome doubt from the mainstream and deaf communities in their early years of development. All contemporary cochlear implants use similar signal processing that extracts temporal envelope information from a limited number of spectral bands, and delivers these envelopes successively to 12-22 electrodes implanted in the cochlea. As a result, these implants produce similarly good speech performance: 70-80 percent sentence recognition in quiet, which allows an average cochlear implant user to carry on a conversation over the telephone. Interestingly, though, sentence recognition in quiet has essentially remained at this same level since 1994. Full Story

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Evaluation of noise reduction technologies in a contemporary cochlear implant system

May 2011

Despite these advances, many cochlear implant users continue to experience substantial difficulty with speech recognition in noisy environments. In particular, recent studies have shown that speech understanding decreases by 30 to 60 percentage points when performance in quiet is compared with performance at commonly-encountered signal-to-noise ratios ranging from +4 and +10 dB.8-11 As a result, cochlear implant manufacturers invest considerable resources into the development of technologies designed to improve speech perception in noise. For example, the newly-introduced Cochlear Nucleus 5 cochlear implant system possesses several features that are intended to improve speech understanding in noisy environments  Full Story

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Single cochlear implant helps you hear in BOTH ears

February 2011

Marnie McCarthy used to think her three teenage sons were pleasantly quiet. But then she heard them properly for the first time and realised just how noisy they really are. Until six months ago, Marnie had never heard the voices of her boys, aged 17, 14 and 12. Nor had she heard the sound of birdsong, laughter or a ringing telephone. That's because Marnie, now 45, was born almost totally deaf.  She wore hearing aids, but her hearing loss had been becoming increasingly worse over the years. Even with the aids, she could hear only the very loudest sounds.  Hearing in two ears allows people to hear speech better and means a patient can hear where a sound is coming from. And because the devices amplify all noise, it was almost impossible for her to pick out voices, even when she was in a quiet environment. Yet she is now able to hear her sons' voices, along with a host of other `new' sounds, thanks to a recent technological breakthrough - a  single cochlear implant that helps you hear in both ears.   Full Story

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Comparison of Bimodal and Bilateral Cochlear Implant Users

September 2010

Objectives: Despite excellent performance in speech recognition in quiet, most cochlear implant users have great difficulty with speech recognition in noise, music perception, identifying tone of voice, and discriminating different talkers. This may be partly due to the pitch coding in cochlear implant speech processing. Most current speech processing strategies use only the envelope information; the temporal fine structure is discarded. One way to improve electric pitch perception is to use residual acoustic hearing via a hearing aid on the nonimplanted ear (bimodal hearing). This study aimed to test the hypothesis that bimodal users would perform better than bilateral cochlear implant users on tasks requiring good pitch perception.    Full Story

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NFMI Technology Promises Wireless CIs

November 2009

The most interesting of the products that they demoed was a cochlear implant where the left and right ears implants could communicate with each other using very short range wireless technology. Cochlear implants are put inside deaf people's skulls to interface directly to nerves. Gradually the deaf person (usually a child) can start to hear as the brain works out what to do with those weird electrical signals that suddenly started to appear. I have a friend whose daughter was born deaf and has a cochlear implant and the transformation is nothing short of incredible. But putting two implants, one for each ear, and having them be able to communicate with each other, makes for even better comprehension. With an inductive interface too, it is possible to use a small box that takes Bluetooth and communicates inductively with the implants, allowing deaf people to use the phone or listen to music much more easily (it's too power hungry just to put a bluetooth receiver in the implant).  Full Story

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Infrared Light May Improve Cochlear Implants

November 2008

Infrared light can stimulate neurons in the inner ear as precisely as sound waves, a discovery that could lead to better cochlear implants for deaf people. A healthy inner ear uses hair cells that respond to sound to stimulate neurons that send signals to the brain. But hair cells can be destroyed by disease or injury, or can contain defects at birth, leading to deafness. In such cases, cochlear implants can directly stimulate neurons. The hearing provided by today's implants is good enough to enable deaf children to develop speech skills that are remarkably similar to hearing children's. Implant users still find it tough to appreciate music, communicate in a noisy environment and understand tonal languages like Mandarin, however. That's because the implants use only 20 or so electrodes, a small number compared to the 3000-odd hair cells in a healthy ear. More sources of stimulation should make hearing clearer but more electrodes cannot be packed in because tissue conducts electricity, so signals from different electrodes would interfere. In contrast, laser light targets nerves more precisely and doesn't spread, which could allow an implant to transmit more information to the neurons.  Full Story

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Doctor Maps CI from Halfway Around the World

March 2008

Through the power of Internet technology, medical experts in New York have switched on an inner-ear device, allowing a man in Uganda to hear for the first time in two years. Activating the device from halfway around the world is a first, and highlights a trailblazing way in which the growing realm of telemedicine - conducting medical procedures from remote locations - can enhance the lives of people in struggling nations.  Full Story

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Should you consider upgrading the INTERNAL CI components?

March 2008