Adaptive gain and filtering circuit for a sound reproduction system
Patent 5724433 Issued on March 3, 1998. Estimated Expiration Date: June 7, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
Adaptive compressive gain and level dependent spectral shaping circuitry for a hearing aid include a microphone to produce an input signal and a plurality of channels connected to a common circuit output. Each channel has a preset frequency response. Each channel includes a filter with a preset frequency response to receive the input signal and to produce a filtered signal, a channel amplifier to amplify the filtered signal to produce a channel output signal, a threshold register to establish a channel threshold level, and a gain circuit. The gain circuit increases the gain of the channel amplifier when the channel output signal falls below the channel threshold level and decreases the gain of the channel amplifier when the channel output signal rises above the channel threshold level. A transducer produces sound in response to the signal passed by the common circuit output.
Other References
Braida et al., "Review of Recent Research on Multiband Amplitude Compression for the Hearing Impaired", 1982 pp. 133-140
Yanick, Jr., "Improvement in Speech Discrimination with Compression vs. Linear Amplification", Journal of Auditory Research, No. 13, 1973, pp. 333-338
Villchur, "Signal Processing to Improve Speech Intelligibility in Perceptive Deafness", The Journal of The Acoustical Society of America, vol. 53, No. 6, 1973, pp. 1646-1657
Braida et al., "Hearing Aids-A Review of Past Research on Linear Amplification, Amplitude Compression, and Frequency Lowering", Asha Monographs, No. 19, Apr. 1979, pp. vii-115
Lim et al., "Enhancement and Bandwidth Compression of Noisy Speech", Proceedings of the IEEE, vol. 67, No. 12, Dec. 1979, pp. 1586-1604
Lippmann et al., "Study of Multichannel Amplitude Compression and Linear Amplification for Persons with Sensorineural Hearing Loss", The Journal of The Acoustical Society of, America, vol. 69, No. 2, Feb. 1981, pp. 524-534
Walker et al., "Compression in Hearing Aids: An Analysis, A Review and Some Recommendations", National Acoustic Laboratories, Report No. 90, Jun. 1982, pp. 1-41
Dillon et al., "Compression-Input or Output Control?", Hearing Instruments, vol. 34, No. 9, 1983, pp. 20, 22 & 42
Laurence et al., "A Comparison of Behind-the-Ear High-Fidelity Linear Hearing Aids and Two-Channel Compression Aids, in the Laboratory and in Everyday Life", British Journal of Audiology, No. 17, 1983, pp. 31-48
Nabelek, "Performance of Hearing-Impaired Listeners under Various Types of Amplitude Compression", The Journal of The Acoustical Society of America, vol. 74, No. 3, Sep. 1983, pp. 776-791
Leijon et al., "Preferred Hearing Aid Gain and Bass-Cut in Relation to Prescriptive Fitting", Scand Audiol, No. 13, 1984 pp. 157-161
Walker et al., "The Effects of Multichannel Compression/Expansion Amplification on the Intelligibility of Nonsense Syllables in Noise", The Journal of The Acoustical Society of America, vol. 76, No. 3, Sep. 1984, pp. 746-757
Moore et al., "Improvements in Speech Intelligibility in Quiet and in Noise Produced by Two-Channel Compression Hearing Aids", British Journal of Audiology, No. 19, 1985, pp. 175-187
Moore et al., "A Comparison of Two-Channel and Single-Channel Compression Hearing Aids", Audiology, No. 25, 1986, pp. 210-226
De Gennaro et al., "Multichannel Syllabic Compression for Severely Impaired Listeners", Journal of Rehabilitation Research and Development, vol. 23, No. 1, 1986, pp. 17-24
Revoile et al., "Some Rehabilitative Considerations for Future Speech-Processing Hearing Aids", Journal of Rehabilitation Research and Development, vol. 23, No. 1, 1986, pp. 89-94
Graupe et al., "A Single-Microphone-Based Self-Adaptive Filter of Noise from Speech and its Performance Evaluation", Journal of Rehabilitation Research and Development, vol. 24, No. 4, Fall 1987, pp. 119-126
Villchur, "Multichannel Compression Processing for Profound Deafness", Journal of Rehabilitation Research and Development vol. 24, No. 4, Fall 1987, pp. 135-148
Bustamante et al., "Multiband Compression Limiting for Hearing-Impaired Listeners", Journal of Rehabilitation Research and Development, vol. 24, No. 4, Fall 1987, pp. 149-160
Yund et al., "Speech Discrimination with an 8-Channel Compression Hearing Aid and Conventional Aids in Background of Speech-Band Noise", Journal of Rehabilitation Research and Development, vol. 24, No. 4, Fall 1987, pp. 161-180
Moore, "Design and Evaluation of a Two-Channel Compression Hearing Aid", Journal of Rehabilitation Research and Development, vol. 24, No. 4, Fall 1987, pp. 181-192
Plomp, "The Negative Effect of Amplitude Compression in Multichannel Hearing Aids in the Light of the Modulation-Transfer Function", The Journal of the Acoustical Society of America, vol. 83, No. 6, Jun. 1988, pp. 2322-2327
Waldhauer et al., "Full Dynamic Range Multiband Compression in a Hearing Aid", The Hearing Journal, Sep. 1988, pp. 29-32
Van Tasell et al., "Effects of an Adaptive Filter Hearing Aid on Speech Recognition in Noise by Hearing-Impaired Subjects", Ear and Hearing, vol. 9, No. 1, 1988, pp. 15-21
Moore et al., "Practical and Theoretical Considerations in Designing and Implementing Automatic Gain Control (AGC) in Hearing Aids", Quaderni di Audiologia, No. 4, 1988, pp. 522-527
Leijon, "1.3.5 Loudness-Density Equalization", Optimization of Hearing-Aid Gain and Frequency Response for Cochlear Hearing Losses, Technical Report No. 189, Chalmers University of Technology, 1989, pp. 17-20
Leijon, "4.7 Loudness-Density Equalization", Optimization of Hearing-Aid Gain and Frequency Response for Cochlear Hearing Losses, Technical Report No. 189, Chalmers University of Technology, 1989, pp. 127-128
Johnson et al., "Digitally Programmable Full Dynamic Range Compression Technology", Hearing Instruments, vol. 40, No. 10 1989, pp. 26-27 & 30
Killion, "A High Fidelity Hearing Aid", Hearing Instruments, vol. 41, No. 8, 1990, pp. 38-39
Van Dijkhuizen, Studies on the Effectiveness of Multichannel Automatic Gain-Control in Hearing Aids, Vrije Universiteit te Amsterdam, 1991, pp. 1-86, in addition to ERRATA sheets, pp. 1 & 2
Rankovic et al., "Potential Benefits of Adaptive Frequency-Gain Characteristics for Speech Reception in Noise", The Journal of The Acoustical Society of America, vol. 91, No. 1, Jan. 1992, pp. 354-362
Moore et al., "Effect on the Speech Reception Threshold in Noise of the Recovery Time of the Compressor in the High-Frequency Channel of a Two-Channel Aid", Scand Audiol, No. 38 1993, pp. 1-1
June 7, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
