Effect of Compression Parameters on the Gain for Kannada Sentence, ISTS and Non-Speech Signals in Hearing Aids

Abstract

International Speech Test Signal (ISTS) is relatively a new stimulus developed for the real ear measurement. The present study aimed to evaluate the differences in a gain of a hearing aid when measured with ISTS and a sentence in Kannada language. The ANSI- weighted digi-speech signal and ICRA- weighted digi-speech signal, ISTS and a Kannada sentence were routed through a calibrated audiometer and presented at a level of 45, 55, 65 and 85 dB SPL. The SPL in the ear canal of an adult individual was recorded using FONIX 8000 real-ear measurement system with the hearing aid on. The SPL was recorded for these stimuli in the ear canal with different compression ratios (2:1 and 3:1), attack time (2 ms, 5 ms and 10 ms), and release time (40 ms, 654 ms and 1280 ms) settings of the hearing aid. The difference in gain was calculated between the non-speech/ISTS and the Kannada sentence. Multilinear regression analysis was done. The results showed that there are differences in the gain of a compression hearing aid when different stimuli are used. The present study also highlights the need for standardizing these differences, for different settings of compression hearing aid, so that, these can be applied while conducting real ear measures with the newer stimuli.