title: Comparison of linear gain and wide dynamic range compression hearing aid circuits II: aided loudness measures.
abstract: OBJECTIVE
  The goal of this study was to test the theoretical advantages of a single-channel wide dynamic range compression (WDRC) circuit fitted using the DSL method for increased dynamic range and normalized loudness growth.
  
  
  METHODS
  Ten adolescents and young adults with moderate to severe sensorineural hearing loss were fitted monaurally with the Siemens Viva 2 Pro behind-the-ear instrument set to DSL 4.0 targets for both linear gain and WDRC processing. Threshold, upper limit of comfort and loudness growth were measured in the unaided, linear gain and WDRC conditions for warble tones, environmental sounds and speech. Twelve adult listeners with normal hearing also were tested monaurally in the unaided condition to provide normative data for comparison purposes.
  
  
  RESULTS
  The WDRC hearing aid provided a greater input dynamic range than the linear circuit for all stimuli. The dynamic range was normalized for more subjects with the WDRC than the linear hearing aid. In addition, exponential loudness growth functions fitted to the loudness growth data showed that, on average, loudness growth was more normalized with the WDRC hearing aid fitted to DSL[i/o] targets than the linear hearing aid fitted to DSL[i/o] targets.
  
  
  CONCLUSIONS
  WDRC processing, fitted using the DSL[i/o] method, has potential applications in hearing aid fittings for listeners with moderate to severe hearing loss because it provides an audible, comfortable and tolerable amplified signal across a wider range of inputs than linear gain processing, without the need for volume control adjustments.
authors.affiliation: National Centre for Audiology, School of Communication Sciences and Disorders, The University of Western Ontario, London, Canada.
authors.forename: L M
authors.initials: LM
authors.lastname: Jenstad
authors.forename: J
authors.initials: J
authors.lastname: Pumford
authors.forename: R C
authors.initials: RC
authors.lastname: Seewald
authors.forename: L E
authors.initials: LE
authors.lastname: Cornelisse
mesh_terms: D000293:Adolescent; D000328:Adult; D006310:Hearing Aids; D006319:Hearing Loss, Sensorineural / Q000534:rehabilitation*; D006801:Humans; D008144:Loudness Perception