Reference hearing threshold levels for chirp signals delivered by an ER-3A insert earphone.
OBJECTIVE
To establish reference hearing threshold levels for chirps and frequency-specific chirps.


METHODS
Hearing thresholds were determined monaurally for broad-band chirps and octave-band chirps using the Etymotic Research, ER-3A insert earphone. The chirps were presented using two repetition rates, 20 and 90 stimuli/s, and with alternating polarity in blocks of one second duration. The test procedure and test conditions were in accordance with the recommendations given in ISO 389-9 (2009) . The ascending method ( ISO 8253-1, 2010 ) was applied using a step size of 5 dB. The chirps were played back from a Tucker Davies Technologies System II, and a Matlab program controlled the test setup. The results are specified in dB peak-to-peak equivalent threshold sound pressure levels (dB peETSPL).


METHODS
The test group consisted of 25 otologically-normal young adults (age 18-25 years).


RESULTS
The results are in good agreement with the results from another investigation of hearing thresholds using the same chirp stimuli, and the values for the octave-band chirps are in line with the standardized reference values for corresponding tone bursts ( ISO 389-6, 2007 ).


CONCLUSIONS
The results of the present investigation are relevant for the international standard on short duration signals, ISO 389-6 (2007) .
Department of Electrical Engineering, Hearing Systems, Technical University of Denmark, Lyngby, Denmark.
Kristian
K
Gøtsche-Rasmussen
Torben
T
Poulsen
Claus
C
Elberling
D000161:Acoustic Stimulation / Q000592:standards*; D000293:Adolescent; D000328:Adult; D001301:Audiometry, Pure-Tone / Q000592:standards; D001309:Auditory Threshold; D005260:Female; D006309:Hearing; D006310:Hearing Aids; D006801:Humans; D008297:Male; D012016:Reference Values; D055815:Young Adult