The Effect of Multichannel Compression on Vowel and Stop‐Consonant Discrimination in Normal‐Hearing and Hearing‐Impaired Subjects

Objective Multichannel compression (MCC) processing can alter the speech spectrum, perhaps reducing spectral contrasts that are important for the discrimination of certain speech sounds. The effect of MCC processing on the discrimination of vowels and voiced stop consonants was studied. Design Vowels and voiced stop consonants were MCC-processed in two ways: 1) FLAT MCC having the same compression ratio in each channel, and 2) SHAPED MCC having compression ratios in each channel adjusted to the auditory area of the particular subject. The stimuli were processed both ways using 2, 4, 8, 16, and 31 independent compression channels. Unprocessed and linearly amplified stimuli were used as control conditions. Normal-hearing and hearing-impaired subjects were tested for changes in discrimination performance as a function of the MCC processing parameters. Results When the MCC processing was adjusted specifically for an individual hearing-impaired subject, no negative effect of increasing numbers of channels (2 to 31) was found. In the case of FLAT MCC processing, increasingly degraded discrimination performance was found for both subject groups as the compression ratio increased and as the number of channels increased. There was also a strong interaction between the effects of the number of channels and the compression ratio, with the negative effects of increasing numbers of channels being much greater at the highest compression ratio. Conclusions Negative effects of MCC were found only for very extreme MCC conditions. MCC processing with compression ratios adjusted in each channel for the individual subject, and having as many as 31 channels, revealed no negative effects on vowel or voiced stop-consonant discrimination. These results do not support the prevalent view that MCC with more than two or three channels will be detrimental and should encourage further research on MCC processing with larger numbers of channels.

[1]  N I Durlach,et al.  Multichannel syllabic compression for severely impaired listeners. , 1986, Journal of rehabilitation research and development.

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

[3]  E W Yund,et al.  Discrimination of Multichannel‐Compressed Speech in Noise: Long‐Term Learning in Hearing‐Impaired Subjects , 1995, Ear and hearing.

[4]  Speech-perception aids for hearing-impaired people: current status and needed research. Working Group on Communication Aids for the Hearing-Impaired. , 1991, The Journal of the Acoustical Society of America.

[5]  M F Dorman,et al.  Minimum spectral contrast for vowel identification by normal-hearing and hearing-impaired listeners. , 1987, The Journal of the Acoustical Society of America.

[6]  Charles E. Robinson,et al.  The Intelligibility of Speech Processed by Delayed Long‐Time‐Averaged Compression Amplification , 1973 .

[7]  L P Sherlock,et al.  Performance with an adaptive frequency response hearing aid in a sample of elderly hearing-impaired listeners. , 1992, Ear and hearing.

[8]  Brian C. J. Moore,et al.  Effects of envelope fluctuations on gap detection , 1992, Hearing Research.

[9]  G. E. Peterson,et al.  Control Methods Used in a Study of the Vowels , 1951 .

[10]  E W Yund,et al.  Multichannel compression hearing aids: effect of number of channels on speech discrimination in noise. , 1995, The Journal of the Acoustical Society of America.

[11]  B C Moore,et al.  Characterization and Simulation of Impaired Hearing: Implications for Hearing Aid Design , 1991, Ear and hearing.

[12]  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.

[13]  J. D. Miller,et al.  Evolving theories of vowel perception a ) , 2022 .

[14]  Nathaniel I. Durlach,et al.  Third-octave analysis of multichannel amplitude compressed speech , 1981, ICASSP.

[15]  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.

[16]  E W Yund,et al.  Speech discrimination with an 8-channel compression hearing aid and conventional aids in background of speech-band noise. , 1987, Journal of rehabilitation research and development.

[17]  R M Cox,et al.  Maturation of hearing aid benefit: objective and subjective measurements. , 1992, Ear and hearing.

[18]  L D Braida,et al.  Principal-component amplitude compression for the hearing impaired. , 1987, The Journal of the Acoustical Society of America.

[19]  R. Lippmann,et al.  Study of multichannel amplitude compression and linear amplification for persons with sensorineural hearing loss. , 1981, The Journal of the Acoustical Society of America.

[20]  B E Walden,et al.  Do adaptive frequency response (AFR) hearing aids reduce 'upward spread' of masking? , 1993, Journal of rehabilitation research and development.

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

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

[23]  D. M. Green,et al.  Stimulus selection in adaptive psychophysical procedures. , 1990, The Journal of the Acoustical Society of America.

[24]  S Gatehouse,et al.  The time course and magnitude of perceptual acclimatization to frequency responses: evidence from monaural fitting of hearing aids. , 1992, The Journal of the Acoustical Society of America.

[25]  E W Yund,et al.  Enhanced speech perception at low signal-to-noise ratios with multichannel compression hearing aids. , 1995, The Journal of the Acoustical Society of America.

[26]  S. Blumstein,et al.  Invariant cues for place of articulation in stop consonants. , 1978, The Journal of the Acoustical Society of America.