title: Hearing aid validation based on 40 Hz auditory steady-state response thresholds.
abstract: OBJECTIVE
  Aided thresholds can be used for prediction of success of hearing aids and to choose between hearing aids and cochlear implants. This study aimed to compare characteristics of aided and unaided auditory steady-state responses (ASSRs).
  
  
  METHODS
  A total of 30 moderate to profoundly hearing-impaired subjects participated in this study. The subjects underwent acoustic immittance, behavioral audiometry, and ASSR with the modulation rate of 40 Hz, first without a hearing aid and then with a hearing aid. Sixteen people with normal hearing and 17 people with severe hearing loss were included in biological calibration of the sound field.
  
  
  RESULTS
  There was a significant difference between unaided behavioral and ASSR thresholds in all test frequencies (mean difference of unaided behavioral ASSR thresholds: 6.19 dB; P = 0.02 at 500 Hz, P < 0.001 at 1000 and 2000 Hz, and P = 0.02 for 4000 Hz). There was also a significant difference between aided behavioral and ASSR thresholds at 1000 and 2000 Hz (P < 0.001) but not at 500 (P = 0.14) and 4000 (P = 0.23) Hz (mean difference of behavioral ASSR thresholds was 4.33 dB). Despite observing any unaided responses, aided thresholds could be recorded in some severe to profoundly hearing-impaired subjects. The number of recordable thresholds was directly related to speech clarity and speech-reading ability. Multi-frequency stimulation elevated the ASSR threshold, especially for the higher frequencies and in the aided condition.
  
  
  CONCLUSIONS
  Functional and ASSR gains show less difference than threshold data. Therefore, comparing gains instead of thresholds is more accurate for validation of hearing aids. The probability of success of hearing aids appears to be poor if ASSRs (especially aided ones) cannot be recorded. If special care is taken in the fitting of hearing aids and the testing conditions, aided ASSR testing could be a useful tool for validation of hearing aids and the cochlear implant decision-making process.
authors.affiliation: Department of Audiology, Faculty of Rehabilitation, Tehran University of Medical Sciences, Iran. Electronic address: sardari.au@gmail.com.
authors.forename: Sara
authors.initials: S
authors.lastname: Sardari
authors.affiliation: Department of Basic Sciences in Rehabilitation, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran; Canadian Center for Behavioral Neuroscience (CCBN), Lethbridge University, Lethbridge, Alberta, Canada. Electronic address: jafari.z@iums.ac.ir.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Jafari
authors.affiliation: Department of Statistics and Mathematics, Faculty of Management, Tehran University of Medical Sciences, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Haghani
authors.affiliation: Department of Audiology, Faculty of Rehabilitation, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Hossain
authors.initials: H
authors.lastname: Talebi
mesh_terms: D000162:Acoustics; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001299:Audiometry / Q000379:methods; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology*; D002138:Calibration; D003054:Cochlear Implants; D003657:Decision Making; D004594:Electrophysiology; D004867:Equipment Design; D005260:Female; D006310:Hearing Aids; D034381:Hearing Loss / Q000175:diagnosis* / Q000503:physiopathology* / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
keywords: Auditory steady-state response; Functional gain; Hearing aid; Validation