We recently had the opportunity to speak with Tetsuji Kunishi, the president of Tokyo-based medical technology company DCC K.K, about his company’s innovative hearing aid technology. Unlike most hearing aids, which rely on air conduction, the DCC K.K.’s PRESTIN hearing aid relies on bone conduction and a technology called Giant Magnetostriction.
Shiv Gaglani, Medgadget: What is the problem with current hearing aids?
Most current hearing aids use an air conducted system. When the hearing aid increases volume to compensate for hearing loss in the ear, damage occurs to hair cells. Once the hair cells die, they cannot be regenerated.
Hair cells are the sensory receptors of hearing and each hair represents a particular frequency. Once that hair cell is damaged and dies, the cochlea cannot recognize that particular frequency. As a result, the recognition of the sound of each word becomes more difficult because the hair cells no longer respond to sound. Prolonged exposure to loud sounds produces strong dynamic forces. As this reaches over the limit the hair cells can handle, they progressively become damaged. Therefore, the solution to this problem should not produce sound. A bone conducted hearing system converts acoustic sounds to vibrations through a transducer, which are then sent directly to the cochlea. This does not create any excessive force on the hair cells.
Medgadget: How did you come up with the idea for this next-generation hearing aid?
Current hearing aids use either Electromagnetic Induction or a Piezoelectric system for the driver (engine). However, the latest sonar technology which is used in submarines has replaced the Electromagnetic Induction/Piezoelectric system with a Giant Magnetostriction system, greatly increasing precision. (In testing, sound generated by the Giant Magnetostriction sonar in San Diego Bay reached all the way to Yokosuka Bay, Japan). This is how the idea came for substituting Giant Magnetostriction for Electromagnetic Induction/Piezoelectricity in hearing aids.
Medgadget: Can you describe how the technology works?
The biggest advantage of Giant Magnetostriction is that it has a 10,000 to 100,000 times faster response speed in comparison to Electromagnetic Induction/Piezoelectricity (depending on the material used). To explain further, the response speed of Giant Magnetostriction is 10 ~ 100 nano seconds, while the response speed of Electromagnetic Induction/Piezoelectricity is only 1 millisecond at its fastest. Therefore, Giant Magnetostriction technology has 10,000 to 100,000 times the ability of current technology to reproduce sound information. This has resulted in a significant improvement in hearing in comparison to existing hearing aids.
Moreover, there are differences in the frequency response: Giant Magnetostriction frequency ranges from 25 Hz to 35k Hz, while Electromagnetic Induction is from 100 Hz to 4k Hz and Piezoelectricity is from 100 Hz to 10k Hz. This results in a large improvement in sound quality for understanding each word clearly in sensorineural hearing loss.
So far, the uses have been limited as Giant Magnetostriction is heavy and requires a comparatively large amount of electric power. However this was resolved by utilizing the latest medical precision instrument technology from Sabae, Japan making it lighter with less power consumption (Sabae has 70% of the world share in manufacturing high quality eyeglasses).
Medgadget: What phase of testing are you in and can you describe the results you’ve experienced?
In the paper, Bone-conducted auditory brainstem-evoked responses and skull vibratory velocity, details are reported of a comparative experiment which applied the same Magnetostrictive principle as a state-of-the-art GMT Magnetostrictive sonar. The performance is extremely impressive and not comparable to any existing hearing aid.
Following the publishing of the above paper, development of a bone conducted hearing aid using a Giant Magnetostrictive transducer (GMT) continued.
In 2012, under the leadership of Professor Emeritus Kimitaka Kaga, M.D., of the University of Tokyo, a grant was received from the Japanese Ministry of Health, Labour and Welfare to help collect clinical data of the effects of the completed PRESTIN® KINOKO hearing aid device for severe hearing loss.
Data from forty cases of patients with moderate to severe hearing loss were collected and analyzed by the Honorary Director of National Hospital Organization,Tokyo Medical Center, Kimitaka Kaga, M.D. <sentence changed>
The clinical data which far exceeded existing performance limitations of existing hearing aids were reported to the Japanese Ministry of Health, Labour and Welfare in April, 2014. The clinical data from patients showed PRESTIN® bone conducted hearing aid can be used for some types of sensorineural hearing loss.Types of hearing difficulty and suitability1. Light-Middle range (25dB-70dB) hearing loss(a) Conductive hearing loss ◎ Very good
(b) Sensorineural hearing loss ◎ Very good2. Severe hearing loss (70dB-90dB)
(a) Conductive hearing loss ◎ Very good
(b) Sensorineural hearing loss ○ Can expect good effect, depending on symptoms
3. Auditory Neuropathy ◎ Very good
4. Profound hearing loss (over 90dB) ○ Some instances of good effect, depending on symptoms
5. Damage to cerebral cortex X No effect
Medgadget: What is your background in audiology or engineering?
Our team is composed of specialists in audiology and otolaryngology. Our medical director, Kimitaka Kaga, M.D., is a world renowned otology surgeon, and specialist in communication disorders of young children. We also have a specialist in Giant Magnetostriction engineering for hearing loss.As the director of DCC K.K., I am a professional audio technology specialist with experience developing professional audio equipment and an extensive background as a recording studio owner and engineer in New York, since 1981. In Japan, I joined a project to develop a special medical mattress named ‘Jewel Beam Fiber’ using natural minus ions to help patients with bed sores achieve a speedy recovery.
How did you come up with the name “Prestin”?
I was inspired by the name that has a similar mechanism as our Giant Magnetostriction driver. The brand name of our product, PRESTIN® was named after Prestin, a protein that is essential to sensitive hearing in mammals. In the inner ear of the cochlea, Prestin is the motor protein of the outer hair cells.
Product page: PRESTIN ‘KINOKO’…