title: Auditory brainstem responses to chirps delivered by different insert earphones.
abstract: The frequency response and sensitivity of the ER-3A and ER-2 insert earphones are measured in the occluded-ear simulator using three ear canal extensions. Compared to the other two extensions, the DB 0370 (Brüel & Kjær), which is recommended by the international standards, introduces a significant resonance peak around 4500 Hz. The ER-3A has an amplitude response like a band-pass filter (1400 Hz, 6 dB/octave -4000 Hz, -36 dB/octave), and a group delay with "ripples" of up to ±0.5 ms, while the ER-2 has an amplitude response, and a group delay which are flat and smooth up to above 10000 Hz. Both earphones are used to record auditory brainstem responses, ABRs, from 22 normal-hearing ears in response to two chirps and a click at levels from 20 to 80 dB nHL. While the click-ABRs are slightly larger for ER-2 than for ER-3A, the chirp-ABRs are much larger for ER-2 than for ER-3A at levels below 60 dB nHL. With a simulated amplitude response of the ER-3A and the smooth group delay of the ER-2 it is shown that the increased chirp-ABR amplitude with the ER-2 is caused by its broader amplitude response and not by its smoother group delay.
authors.affiliation: William Demant Holding A/S, Kongebakken 9, DK-2765 Smørum, Denmark. ce@demant.dk
authors.forename: Claus
authors.initials: C
authors.lastname: Elberling
authors.forename: Sinnet G B
authors.initials: SG
authors.lastname: Kristensen
authors.forename: Manuel
authors.initials: M
authors.lastname: Don
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000162:Acoustics / Q000295:instrumentation*; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D011930:Reaction Time