Non-linear signal processing in digital hearing aids.

Three different non-linear digital signal processing algorithms were developed; LinEar, DynEar and RangeEar. All three provided individual frequency shaping via a seven-band low-power filterbank and compression in two channels. RangeEar and DynEar used wide dynamic range syllabic compression in the low-frequency (LF) channel, while LinEar used compression limiting. In the high-frequency (HF) channel, RangeEar used a slow-acting automatic volume control, while DynEar and LinEar used compression limiting. Wearable digital signal processing-based experimental instruments were used to evaluate the fitting algorithms under real world conditions with experienced hearing aid users. Evaluation included laboratory testing of speech recognition in noise and questionnaires on sound quality ratings. Results did not indicate one general good-for-all algorithm, but different algorithms resulting in preference and performance depending on the hearing loss configuration. Preference for any of the new algorithms could be predicted based on auditory dynamic range measurements. It was hypothesized that the different preferences were affected by different susceptibility to masking of HF sounds by amplified LF sounds.

[1]  C Elberling,et al.  Loudness summation across frequency under masking and in sensorineural hearing loss. , 1980, Audiology : official organ of the International Society of Audiology.

[2]  T Lunner,et al.  A Digital Filterbank Hearing Aid: Three Digital Signal Processing Algorithms‐User Preference and Performance , 1997, Ear and hearing.

[3]  Hawkins Db,et al.  Comparison of sound quality and clarity with asymmetrical peak clipping and output limiting compression. , 1993 .

[4]  R. Plomp.  Noise, Amplification, and Compression: Considerations of Three Main Issues in Hearing Aid Design , 1994, Ear and hearing.

[5]  M J Osberger,et al.  Discrimination of formant frequency transitions in synthetic vowels. , 1973, Journal of speech and hearing research.

[6]  J. Olsen,et al.  From acoustic amplification to hearing loss compensation , 1993 .

[7]  C. Turner,et al.  Spread of masking in normal subjects and in subjects with high-frequency hearing loss. , 1986, Audiology : official organ of the International Society of Audiology.

[8]  Bryan F. J. Manly,et al.  Multivariate Statistical Methods : A Primer , 1986 .

[9]  J Barfod.  Multichannel compression hearing aids: experiments and consideration on clinical applicability. , 1978, Scandinavian audiology. Supplementum.

[10]  Mark B. Gardner,et al.  The Dependence of Hearing Impairment on Sound Intensity , 1937 .

[11]  R Plomp,et al.  The negative effect of amplitude compression in multichannel hearing aids in the light of the modulation-transfer function. , 1988, The Journal of the Acoustical Society of America.

[12]  B Hagerman,et al.  Clinical measurements of speech reception threshold in noise. , 1984, Scandinavian audiology.

[13]  Thomas Lunner,et al.  A digital filterbank hearing aid-design, implementation and evaluation , 1991, [Proceedings] ICASSP 91: 1991 International Conference on Acoustics, Speech, and Signal Processing.

[14]  D Benson,et al.  Patient experiences with multiband full dynamic range compression. , 1992, Ear and hearing.

[15]  E Villchur,et al.  Signal processing to improve speech intelligibility in perceptive deafness. , 1973, The Journal of the Acoustical Society of America.

[16]  H. Dillon,et al.  The National Acoustic Laboratories' (NAL) New Procedure for Selecting the Gain and Frequency Response of a Hearing Aid , 1986, Ear and hearing.

[17]  M. Leek,et al.  Intraspeech spread of masking in normal-hearing and hearing-impaired listeners. , 1997, The Journal of the Acoustical Society of America.

[18]  D B Hawkins,et al.  Comparison of sound quality and clarity with asymmetrical peak clipping and output limiting compression. , 1993, Journal of the American Academy of Audiology.

[19]  C Elberling,et al.  A Digital Filterbank Hearing Aid: Predicting User Preference And Performance For Two Signal Processing Algorithms , 1997, Ear and hearing.

[20]  B Hagerman,et al.  Efficient adaptive methods for measuring speech reception threshold in quiet and in noise. , 1995, Scandinavian audiology.

[21]  S Mangold,et al.  Programmable hearing aid with multichannel compression. , 1979, Scandinavian audiology.

[22]  H Dillon.  Tutorial Compression? Yes, But for Low or High Frequencies, for Low or High Intensities, and with What Response Times? , 1996, Ear and hearing.

[23]  J M Festen,et al.  The effect of frequency-selective attenuation on the speech-reception threshold of sentences in conditions of low-frequency noise. , 1991, The Journal of the Acoustical Society of America.

[24]  B C Moore,et al.  Perceptual consequences of cochlear hearing loss and their implications for the design of hearing aids. , 1996, Ear and hearing.

[25]  Edgar Villchur.  Comments on ‘‘The negative effect of amplitude compression in multichannel hearing aids in the light of the modulation‐transfer function’’ [J. Acoust. Soc. Am. 83, 2322–2327 (1988)] , 1989 .

[26]  J. Gagné,et al.  Excess masking among listeners with a sensorineural hearing loss. , 1988, The Journal of the Acoustical Society of America.

[27]  K Mizoi,et al.  Clinical results of hearing aid with noise-level-controlled selective amplification. , 1983, Audiology : official organ of the International Society of Audiology.

[28]  V Pluvinage,et al.  Evaluation of a dual-channel full dynamic range compression system for people with sensorineural hearing loss. , 1992, Ear and hearing.

[29]  B E Walden,et al.  Description and validation of an LDL procedure designed to select SSPL90. , 1987, Ear and hearing.