A simplified measurement method of auditory filters for hearing-impaired listeners

A simplified method for the measurement of auditory filter, in which the filter shape is assumed to be symmetric, is proposed. This method would apply to the clinical diagnosis of hearing impairment and the fitting of hearing aids. The proposed method is based on the notched-noise method and includes procedures for the determination of the masker level and for the estimation of the auditory filter shape from one masked threshold. In order to reduce measuring time, the ascending method is used to detect the signal threshold level in this method. Two experiments were conducted to evaluate this proposed technique: (1) the measurement accuracy of the ascending method was investigated on three normal-hearing subjects and compared with the 2AFC method, and (2) the practicability of this simplified method was evaluated on eleven hearing-impaired and two normal-hearing subjects, and compared with the conventional notched-noise method. Results showed that (1) the ascending method has sufficient accuracy for the measurement of the masked threshold and (2) ERB data obtained using the simplified method correlate highly with ERB data obtained using the conventional notched-noise method. It was also shown that each auditory filter could be measured in approximately three minutes.