title: Encoding of speech sounds at auditory brainstem level in good and poor hearing aid performers.
abstract: BACKGROUND
  Hearing aids are prescribed to alleviate loss of audibility. It has been reported that about 31% of hearing aid users reject their own hearing aid because of annoyance towards background noise. The reason for dissatisfaction can be located anywhere from the hearing aid microphone till the integrity of neurons along the auditory pathway.
  
  
  OBJECTIVE
  To measure spectra from the output of hearing aid at the ear canal level and frequency following response recorded at the auditory brainstem from individuals with hearing impairment.
  
  
  METHODS
  A total of sixty participants having moderate sensorineural hearing impairment with age range from 15 to 65 years were involved. Each participant was classified as either Good or Poor Hearing aid Performers based on acceptable noise level measure. Stimuli /da/ and /si/ were presented through loudspeaker at 65dB SPL. At the ear canal, the spectra were measured in the unaided and aided conditions. At auditory brainstem, frequency following response were recorded to the same stimuli from the participants.
  
  
  RESULTS
  Spectrum measured in each condition at ear canal was same in good hearing aid performers and poor hearing aid performers. At brainstem level, better F0encoding; F0and F1energies were significantly higher in good hearing aid performers than in poor hearing aid performers. Though the hearing aid spectra were almost same between good hearing aid performers and poor hearing aid performers, subtle physiological variations exist at the auditory brainstem.
  
  
  CONCLUSIONS
  The result of the present study suggests that neural encoding of speech sound at the brainstem level might be mediated distinctly in good hearing aid performers from that of poor hearing aid performers. Thus, it can be inferred that subtle physiological changes are evident at the auditory brainstem in a person who is willing to accept noise from those who are not willing to accept noise.
authors: All India Institute of Speech and Hearing, Department of Audiology, Mysuru, Karnataka, India. Electronic address: hemanthn.shetty@gmail.com.
authors: Hemanth Narayan
authors: HN
authors: Shetty
authors: All India Institute of Speech and Hearing, Department of Audiology, Mysuru, Karnataka, India.
authors: Manjula
authors: M
authors: Puttabasappa
mesh_terms: D000161:Acoustic Stimulation; D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D000368:Aged; D001309:Auditory Threshold / Q000502:physiology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006310:Hearing Aids; D006319:Hearing Loss, Sensorineural / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009622:Noise; D013017:Sound Localization; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult
keywords: Acceptable noise level; Frequency following response; Frequência seguida de resposta; Hearing aid performer; Nível de ruído aceitável; Usuário de aparelho auditivo