title: Polarity stimulation effects on brainstem auditory evoked potentials.
abstract: Brainstem Auditory Evoked Potentials are considered exogenous potentials, that is, the responses obtained are highly dependent upon the characteristic of the stimulus used to evoke them.
  
  
  OBJECTIVE
  To investigate the influence of the click stimulus polarity in the study of Brainstem Evoked Response Audiometry (BERA) at different intensities, using insertion-canal earphones.
  
  
  METHODS
  Clinical.
  
  
  METHODS
  33 individuals, aged between 18 and 28, with no auditory alteration were submitted to BERA testing, with click stimulus on the rarefaction, condensation and alternate polarities, in different intensities.
  
  
  RESULTS
  The absolute latencies of the V wave proved to be lower in the rarefaction polarity when compared to the others and, at 80 dBnHL, there was a significant difference between rarefaction and the other polarities for interpeak latencies III-V and I-V. There was a high correlation between the condensation and alternating polarities for absolute and interpeak latencies at 80 dBnHL.
  
  
  CONCLUSIONS
  the click stimulus polarity has a significant influence on BERA. In the routine use of the TDH 39 earphone, with alternating polarity, we suggest that condensation polarity is more adequate for standardized comparison purposes, due to the higher similarity of the latencies found in this insertion earphone study.
authors.affiliation: Speech therapist.
authors.forename: Janaina Patricio
authors.initials: JP
authors.lastname: de Lima
authors.affiliation: Doctor, Livre-Docente (habilitation) professor.
authors.forename: Kátia
authors.initials: K
authors.lastname: de Freitas Alvarenga
authors.affiliation: Speech therapist.
authors.forename: Tábata Pierini
authors.initials: TP
authors.lastname: Foelkel
authors.affiliation: Speech therapist.
authors.forename: Camila Zotelli
authors.initials: CZ
authors.lastname: Monteiro
authors.affiliation: Speech therapist. Universidade de São Paulo- Faculdade de Odontologia de Bauru - Departamento de Fonoaudiologia (Speech Therapy Department).
authors.forename: Raquel Sampaio
authors.initials: RS
authors.lastname: Agostinho
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001300:Audiometry, Evoked Response / Q000379:methods*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D034381:Hearing Loss / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D055815:Young Adult