Identification of Perceptual Cues for Consonant Sounds and the Influence of Sensorineural Hearing Loss on Speech Perception

Abstract

A common problem for people with hearing loss is that they can hear the noisy speech, with the assistance of hearing aids, but still they cannot understand it. To explain why, the following two questions need to be addressed: (1) What are the perceptual cues making up speech sounds? (2) What are the impacts of different types of hearing loss on speech perception? For the first question, a systematic psychoacoustic method is developed to explore the perceptual cues of consonant sounds. Without making any assumptions about the cues to be identified, it measures the contribution of each subcomponent to speech perception by time truncating, high/low-pass filtering, or masking the speech with white noise. In addition, AI-gram, a tool that simulates auditory peripheral processing, is developed to show the audible components of a speech sound on the basilar membrane. For the second question, speech perception experiments are used to determine the difficult sounds for the hearing-impaired listeners. In a case study, an elderly subject (AS) with moderate to severe sloping hearing loss, trained in linguistics, volunteered for the pilot study. Results show that AS cannot hear /ka/ and /ga/ with her left ear, because of a cochlear dead region from 2 to 3.5 kHz, where we show that the perceptual cues for /ka/ and /ga/ are located. In contrast, her right ear can hear these two sounds with low accuracy. NAR-L improves the average score by 10%, but it has no effect on the two inaudible consonants.