Development of a Hearing Impairment Simulator considering Frequency Selectivity of the Hearing Impaired

Institute for Information and Electronics Research, Inha University(Received January 7, 2009. Accepted February 17, 2009)In this paper, we propose a hearing impairment simulator considering reduced frequency selectivity of the hearing impaired, and verify it's performance through experiments. The reduced frequency selectivity was embodied by spectral smearing using linear prediction coding(LPC). The experiments are composed of 4 kinds of tests; pure tone test, speech reception threshold(SRT) test, and word recognition score(WRS) test without spectral smearing and with spectral smearing. The experiments of the hearing impairment simulator were performed with 9 subjects who have normal hearing. The amount of spectral smearing was controlled by LPC order. The percentile score of WRS test without smearing is 89.78±2.420%. The scores of WRS with 24th LPC order and with 8th LPC order are 88.00±3.556% and 83.78±2.123% respectively. It is verified that WRS score is lowered by decreasing LPC order. This is a reasonable result considering that spectral smearing is getting heavier according to decreasing LPC order. It is confirmed that spectral smearing using LPC simulates the reduced frequency selectivity of the hearing impaired and affects the clearness of speech reception. Hearing impairment simulator, Frequency selectivity, Linear prediction coding, Word recognition score