title: Are chirps better than clicks and tonebursts for evoking middle latency responses?
abstract: BACKGROUND
  The middle latency response (MLR) is considered a valid clinical tool for assessing the integrity of cortical and subcortical structures. Several investigators have demonstrated that a rising frequency chirp stimulus is capable of eliciting not only larger wave V amplitudes but larger MLR components as well. However, the chirp has never been specifically examined in a hemispheric electrode montage setup that is typical for neurodiagnostic application and site-of-lesion testing.
  
  
  OBJECTIVE
  The purpose of this study was to examine the effect of chirp, click, and toneburst stimuli on MLR waveform peak latency and peak-to-peak amplitude in a hemispheric electrode montage setup.
  
  
  METHODS
  This study used a repeated-measures design.
  
  
  METHODS
  A total of 10 young adult participants (3 males, 7 females) with normal hearing were recruited and had negative histories of audiologic, otologic, and neurologic involvement, and no reported language or learning difficulties.
  
  
  METHODS
  MLR latencies (Na, Pa, Nb, and Pb) and peak-to-peak amplitudes (Na-Pa, Pa-Nb, and Nb-Pb) were measured for all conditions and were statistically evaluated for left hemisphere-right ear (C3-A2) and right hemisphere-left ear (C4-A1) recordings.
  
  
  RESULTS
  Statistical analyses revealed no significant difference between C3-A2 and C4-A1 peak-to-peak amplitudes; therefore, data were collapsed. Stimulus comparisons revealed that Na evoked by tonebursts were statistically prolonged compared with both chirp and click, and that both Na-Pa and Pa-Nb peak-to-peak amplitudes were statistically larger for chirps compared with both clicks and tonebursts, and for clicks compared with tonebursts.
  
  
  CONCLUSIONS
  The results of this study support the hypothesis that a chirp would offer a clinical advantage to the click and toneburst in overall peak-to-peak amplitude. As expected, normal-hearing participants did not exhibit hemispheric differences when comparing C3-A2 and C4-A1 peak-to-peak amplitudes demonstrating symmetric auditory brain function. However, chirp-evoked MLRs will require further study to determine its usefulness in clinical practice.
authors.affiliation: Department of Audiology and Speech Pathology, University of Arkansas at Little Rock/University of Arkansas for Medical Sciences, Little Rock.
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Atcherson
authors.affiliation: Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock.
authors.forename: Page C
authors.initials: PC
authors.lastname: Moore
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006309:Hearing; D006801:Humans; D008297:Male; D011930:Reaction Time