SBIR-STTR Award

Hearing impairment is most commonly experienced as loss of sensitivity to weak sounds, while intense sounds can be as loud and uncomfortable as in normal hearing. State-of-the-art hearing aids treat this phenomenon of "loudness recruitment" with sound amplification that automatically decreases with sound amplitude. This compresses the range of normally experienced sound amplitudes to the smaller range required by the impaired ear. The best engineering approach to compression is uncertain. Rapid compression amplifiers protect the ear from uncomfortable changes in loudness, but distort the sound waveform. Slowly adapting compression avoids the distortion, but allows some discomfort. Basic research on cochlear responses to sounds has revealed biological mechanisms for both rapid and slow compression that are normally used in hearing. In research sponsored by the National Institutes of Health, the principal investigator has developed models of nonlinear cochlear sound processing, which suggest optimum compression strategies that maximize protection against uncomfortable loudness while minimizing distortion. Algorithms for improved multichannel hearing aids based on these models have been developed and systematically simulated. The goal of Phase I is to implement the algorithms as a prototype master hearing aid that can be used for clinical testing and development of commercial designs. PROPOSED COMMERCIAL APPLICATION: The master hearing aid has commercial application as a clinical and industrial research instrument for the fitting and design of hearing aids. Clinical research in Phase II will quantify the benefits of the novel designs and guide their commercialization.

Thesaurus Terms:
auditory discrimination, biomedical equipment development, clinical biomedical equipment, hearing aid, loudness, sound impedance biological information processing, biological model, cochlea, sound frequency bioengineering /biomedical engineering

Hearing impairment is commonly experienced as loss of sensitivity to weak sounds, while intense sounds can remain as loud as in normal hearing. Many current hearing aids treat this phenomenon of loudness recruitment" with sound amplification that decreases with sound intensity, to provide normal loudness. Design of such compressive amplifiers is controversial. In research sponsored by the NIH the PI developed models of nonlinear cochlear sound processing, which suggest compression strategies that prevent overamplification while minimizing distortion and disturbance by background noise. In Phase-I, algorithms were developed for multichannel hearing aids using both rapid and slow compression mechanisms. Benefits of the new design were demonstrated with a computer simulation in pilot tests on normal and impaired hearing subjects for their understanding of speech in iroise. New insights are provided on functions of nonlinear cochlear mechanisms lacking in impaired ears. An advanced real-time implementation was developed in Phase-I. In Phase-II, prototype wearable hearing aids will be developed, fabricated, and formally tested by independent laboratories. Preliminary simulations of custom miniaturization technologies will be conducted in preparation for commercialization. In addition, the design will be developed as a desktop master hearing aid for clinical optimization of individual fittings. PROPOSED COMMERCIAL APPLICATION: Wider acceptibility of hearing aids is potentiated by the superior performance of the new design, particularly in background noise. The fundamental relationship of the new design to cochlear mechanisms potentiates a professional-instrument market for a full-featured master hearing aid for use in R & D and clinical fitting.

Thesaurus Terms:
auditory discrimination, biomedical equipment development, clinical biomedical equipment, cochlea, hearing aid, loudness, sound impedance biological information processing, biological model, miniature biomedical equipment, sound frequency bioengineering /biomedical engineering