title: Ranking hearing aid input-output functions for understanding low-, conversational-, and high-level speech in multitalker babble.
abstract: OBJECTIVE
  To determine the rankings of 6 input-output functions for understanding low-level, conversational, and high-level speech in multitalker babble without manipulating volume control for listeners with normal hearing, flat sensorineural hearing loss, and mildly sloping sensorineural hearing loss.
  
  
  METHODS
  Peak clipping, compression limiting, and 4 wide dynamic range compression (WDRC) input-output functions were compared in a repeated-measure design. Interactions among the compression characteristics were minimized. Speech and babble were processed and recorded at 3 input levels: 45, 65, and 90 dB sound pressure level. Speech recognition of 3 groups of listeners (n = 6/group) was tested for speech processed by each input-output function and at each input level.
  
  
  RESULTS
  Input-output functions that made low-level speech audible and high-level speech less distorted by avoiding peak clipping or severe compression yielded higher speech recognition scores. These results are consistent with previous findings in the literature.
  
  
  CONCLUSIONS
  WDRCs with the low compression ratio region extended to a high input level or with a high compression limiting threshold were the best for speech recognition in babble when the hearing aid user cannot or does not want to manipulate the volume control. Future studies on subjective preferences of different input-output functions are needed.
authors.affiliation: Northwestern University, New York, USA. kingchung@purdue.edu
authors.forename: King
authors.initials: K
authors.lastname: Chung
authors.forename: Mead C
authors.initials: MC
authors.lastname: Killion
authors.forename: Laurel A
authors.initials: LA
authors.lastname: Christensen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D004867:Equipment Design; D005260:Female; D006310:Hearing Aids; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017755:Prosthesis Fitting; D012720:Severity of Illness Index; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013067:Speech Perception