title: [Auditory fatigue].
abstract: OBJECTIVE
  Given the relevance of possible hearing losses due to sound overloads and the short list of references of objective procedures for their study, we provide a technique that gives precise data about the audiometric profile and recruitment factor. Our objectives were to determine peripheral fatigue, through the cochlear microphonic response to sound pressure overload stimuli, as well as to measure recovery time, establishing parameters for differentiation with regard to current psychoacoustic and clinical studies.
  
  
  METHODS
  We used specific instruments for the study of cochlear microphonic response, plus a function generator that provided us with stimuli of different intensities and harmonic components. In Wistar rats, we first measured the normal microphonic response and then the effect of auditory fatigue on it.
  
  
  RESULTS
  Using a 60dB pure tone acoustic stimulation, we obtained a microphonic response at 20dB. We then caused fatigue with 100dB of the same frequency, reaching a loss of approximately 11dB after 15minutes; after that, the deterioration slowed and did not exceed 15dB. By means of complex random tone maskers or white noise, no fatigue was caused to the sensory receptors, not even at levels of 100dB and over an hour of overstimulation.
  
  
  CONCLUSIONS
  No fatigue was observed in terms of sensory receptors. Deterioration of peripheral perception through intense overstimulation may be due to biochemical changes of desensitisation due to exhaustion. Auditory fatigue in subjective clinical trials presumably affects supracochlear sections. The auditory fatigue tests found are not in line with those obtained subjectively in clinical and psychoacoustic trials.
authors.affiliation: Unidad de Neurofisiología Experimental, Hospital Ramón y Cajal, Madrid, España.
authors.forename: Julio
authors.initials: J
authors.lastname: Sanjuán Juaristi
authors.affiliation: Unidad de Neurofisiología Experimental, Hospital Ramón y Cajal, Madrid, España. Electronic address: marsanjuan@gmail.com.
authors.forename: Mar
authors.initials: M
authors.lastname: Sanjuán Martínez-Conde
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001301:Audiometry, Pure-Tone; D001305:Auditory Fatigue / Q000502:physiology*; D003055:Cochlear Microphonic Potentials; D004867:Equipment Design; D018072:Hair Cells, Auditory, Outer / Q000502:physiology; D009622:Noise / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar
keywords: Acoustic trauma; Auditory fatigue; Fatiga auditiva; Reclutamiento; Recruitment; Trauma acústico