Reference hearing threshold levels for chirp signals delivered by an ER-3A insert earphone

* Department of Electrical Engineering, Hearing Systems, Technical University of Denmark , Lyngby , Denmark.
International journal of audiology (Impact Factor: 1.84). 08/2012; 51(11):794-9. DOI: 10.3109/14992027.2012.705901
Source: PubMed


Abstract Objective: To establish reference hearing threshold levels for chirps and frequency-specific chirps. Design: 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). Study sample: 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) .

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