Effect of Spectro-Temporal Enhancement on Speech Perception in Individuals with Cochlear Hearing Loss

Abstract

Current amplification devices for cochlear hearing loss have not proved to be beneficial in improving speech perception in noisy conditions as they fail to restore normal physiology of the auditory system and hence, the speech perception ability. Signal enhancement strategies might help them to improve their speech perception if the signals are presented at a comfortable level. Hence, the current study was taken up with a primary objective of comparing two strategies (companding & consonant enhancement) in the same population. The study consisted of normal hearing participants who served as control group (N=14) and individuals with cochlear hearing loss who served as clinical group (N=16). They were given a task of consonant identification for 19 consonants in the context of vowel /a/ which were presented in 3 conditions- unprocessed, companded and consonant enhanced at 5 SNRs (0, +5, +10, +15 and quiet). A significant improvement with consonant enhancement was seen at 15 dB SNR and 0 dB SNR for the control and clinical group, respectively. At lower SNRs, both the groups showed a significant improvement with increase in SNR. However, across SNR, control group performed like in quiet situations at 10 dB SNR itself whereas the clinical group required further reduction (15 dB SNR) in noise to obtain such results. Sequential Information Feature Analysis (SINFA) for CHL with flat and sloping configuration revealed maximum information transmission for manner cues followed by place and voicing cues in both groups. Consonant enhancement increased the spectral contrast in speech and hence proved beneficial in individuals with CHL in adverse listening conditions. Thus, it can be used as a rehabilitation technique in amplification devices.