title: Brainstem Encoding of Aided Speech in Hearing Aid Users with Cochlear Dead Region(s).
abstract: BACKGROUND
  Neural encoding of speech begins with the analysis of the signal as a whole broken down into its sinusoidal components in the cochlea, which has to be conserved up to the higher auditory centers. Some of these components target the dead regions of the cochlea causing little or no excitation. Measuring aided speech-evoked auditory brainstem response elicited by speech stimuli with different spectral maxima can give insight into the brainstem encoding of aided speech with spectral maxima at these dead regions.
  
  
  OBJECTIVE
  This research aims to study the impact of dead regions of the cochlea on speech processing at the brainstem level after a long period of hearing aid use.
  
  
  METHODS
  This study comprised 30 ears without dead regions and 46 ears with dead regions at low, mid, or high frequencies. For all ears, we measured the aided speech-evoked auditory brainstem response using speech stimuli of low, mid, and high spectral maxima.
  
  
  RESULTS
  Aided speech-evoked auditory brainstem response was producible in all subjects. Responses evoked by stimuli with spectral maxima at dead regions had longer latencies and smaller amplitudes when compared with the control group or the responses of other stimuli.
  
  
  CONCLUSIONS
  The presence of cochlear dead regions affects brainstem encoding of speech with spectral maxima perpendicular to these regions. Brainstem neuroplasticity and the extrinsic redundancy of speech can minimize the impact of dead regions in chronic hearing aid users.
authors.affiliation: Audiology unit, Otorhinolaryngology department, Faculty of Medicine, Zagazig University, Zagazig, Sharkia, Egypt.
authors.forename: Mohammad Ramadan
authors.initials: MR
authors.lastname: Hassaan
authors.affiliation: Audiology unit, Otorhinolaryngology department, Faculty of Medicine, Zagazig University, Zagazig, Sharkia, Egypt.
authors.forename: Ola Abdallah
authors.initials: OA
authors.lastname: Ibraheem
authors.affiliation: Audiology unit, Otorhinolaryngology department, Faculty of Medicine, Zagazig University, Zagazig, Sharkia, Egypt.
authors.forename: Dalia Helal
authors.initials: DH
authors.lastname: Galhom
keywords: auditory brain stem response; hearing aids; speech perception