6-1. The EarLens System: New Sound Transduction Methods*
Rodney Perkins(1), Jonathan P. Fay(1), Lisa Olson(1), Paul Rucker(1), Micha Rosen(1), Lee Felsenstein(1), Sunil Puria(1,2)
Affiliation: 1) EarLens Corporation, 200 Chesapeake Drive, Redwood City, CA 94063; 2) Stanford University, Stanford CA, 94305
ABSTRACT:
Hypothesis: The hypothesis that an open canal hearing device with a microphone in the ear canal can provide amplification over a wide-bandwidth is tested. Background: A thin silicone platform with an embedded transducer is placed on the tympanic membrane. The perception of sound is created when the “tympanic transducer” vibrates. A microphone placed in the ear canal senses the environmental sound including sound localization cues and addresses the most common problem experienced by the hearing impaired: understanding a target speaker in a multi-talker environment. Methods: Sixteen subjects (normal to moderate hearing impairment) wore the tympanic transducer for up to a six-month period were monitored for any adverse reactions. Three key functional characteristics were measured: maximum effective sound pressure level, feedback gain margin, and tympanic membrane damping. Results: Measurements indicate that the tympanic transducer remained in place and was well tolerated. With the tympanic transducer, the system had sufficient output to treat 60 dB of hearing impairment up to 8 kHz in 84% of the population and up to 11.2 kHz in 50% of the population. The feedback gain margin was on average 30 dB except at the ear canal resonance frequencies of 3 and 9 kHz where the average was reduced to 12 dB and 23 dB, respectively. The maximum tympanic membrane damping of 5-8 dB was in the 2-4 kHz range. The clinical data presented is for a magnetic implementation of the tympanic transducer. Other variations using different types of energy are discussed. Conclusions: The tympanic transducer and associated system has a wide effective bandwidth and little feedback, which opens up possibilities for a unique hearing system. The intra canal microphone configuration will provide the high frequency pinna diffraction cues (>6kHz) to facilitate better hearing in multi-talker environments. Work supported in part by NIDCD/NIH SBIR grants and approved by WIRB #20061405.
Total time: 12 minutes
Comments
6-1
Dear Dr. Perkins,
congratulations on your new concept with the ear-lens. My only concern is the feed-back problem: how does your microphone in the ear canal cope with the amplified sound pressure which radiates from the stimulated vibrating drum outwards, too?If you can overcome this principal problem, which is inherent in all concepts of totally implantable hearing aids, some interesting indications for this easy to place device are waiting...
Feedback challenges
Dear Dr. Huettenbrink,
Thank you for your insightful comments. The feedback from the vibrating eardrum is indeed one of the primary challenges with our device. As you state above, we also expect that the feedback in the EarLens case would be very similar to the feedback experienced by other middle ear implanted hearing aids. It would be very helpful if anyone in the middle ear community has data on the sound pressure generated in the ear canal by a given amount of output of a middle ear implant. As for handling the feedback problem, we do expect that current state-of-the-art feedback canceling algorithms will provide adequate gain margin to treat the mild to moderate hearing impaired patient. However, if algorithms alone are not sufficient, we do have a number of system changes that can be made to help reduce the feedback further. The feedback challenge is definitely something that we will be exploring the in coming months and will be reporting on at future meetings. If anyone in the community has specific knowledge of feedback in the ear canal by middle ear implanted devices, I would love to discuss it and learn from your experiences.