Verification of Hearing Aid Selection Using Visible Speech and Speech Intelligibility Index

Abstract

Verification of hearing aid selection is a major step in the hearing aid fitting process. For verification of hearing aid performance, functional gain measurement for warble tone or speech material and real ear measurements (REM) using tones, composite signals and speech like stimuli are used. The traditional REM utilizes composite noise signals which are not encountered routinely in real life situations and hence inappropriate for testing high end digital hearing aids. The present study was taken up to verify the selection of hearing aids using actual speech. Visible speech measure along with speech intelligibility index was utilized for verification of hearing aid selection. The participant group comprised of 30 naïve hearing aid users, with post-lingual onset of hearing loss. Individuals with hearing impairment were divided into three groups based on degree of hearing loss. Fonix 7000 hearing aid analyzer was used for the traditional real ear measurement protocol which utilizes ANSI-digi speech as stimulus while the visible speech protocol used actual recorded speech. Speech intelligibility index was also tabulated from the visible speech display screen. Speech identification scores were obtained in two different conditions, i.e., when the hearing aid was optimized using traditional real ear aided gain using ANSI-digi speech signal, and other condition was when the hearing aid was optimized using visible speech measure. Findings of the present study reveal that verification of hearing aid using visible speech protocol led to higher speech identification scores. Also, there was a positive correlation between speech identification scores and speech intelligibility index. Hence, verification of hearing aid selection using visible speech protocol and speech intelligibility index yield better performance in individuals with varying degree of hearing loss.