title: Multichannel compression: effects of reduced spectral contrast on vowel identification.
abstract: OBJECTIVE
  To clarify if large numbers of wide dynamic range compression channels provide advantages for vowel identification and to measure its acoustic effects. Methods Eight vowels produced by 12 talkers in the /hVd/ context were compressed using 1, 2, 4, 8, and 16 channels. Formant contrast indices (mean formant peak minus mean formant trough; maximum formant peak minus minimum formant trough) were developed to quantify spectral changes. Twenty listeners with mild to moderately severe sensorineural hearing loss identified the compressed vowels in an 8-alternative forced-choice procedure.
  
  
  RESULTS
  Formant contrast measures revealed significant spectral flattening for 6 of the 8 vowels as channel number increased. A significant decrease in vowel identification performance was also observed as spectral contrast decreased.
  
  
  CONCLUSIONS
  Increasing the number of wide dynamic range compression channels may not be beneficial for all speech signals, and individual vowel identification performance can vary greatly for listeners with similar hearing loss.
authors.affiliation: Hearing Aid Laboratory, Department of Speech and Hearing Sciences, University of Washington, 1417 N.E. 42nd Street, Box 354875, Seattle, WA 98105-6246, USA. stebor@u.washington.edu
authors.forename: Stephanie
authors.initials: S
authors.lastname: Bor
authors.forename: Pamela
authors.initials: P
authors.lastname: Souza
authors.forename: Richard
authors.initials: R
authors.lastname: Wright
mesh_terms: D000161:Acoustic Stimulation; D000368:Aged; D000369:Aged, 80 and over; D006310:Hearing Aids; D006319:Hearing Loss, Sensorineural / Q000628:therapy*; D006801:Humans; D008875:Middle Aged; D013018:Sound Spectrography; D013061:Speech Acoustics; D013067:Speech Perception