Experimental Evaluation of Improvement in Consonant Recognition for the Hearing- Impaired Listeners: Role of Consonant-vowel Intensity Ratio

One of the most common complaints expressed by individuals with hearing loss is the difficulty in understanding speech when listening in background noise. This paper highlights the importance of enhancement of an important acoustic attribute of clear speech -‘Consonant-Vowel intensity ratio’. A case for synthetic clear speech in the context of hearing impairment was developed. Consonant recognition in noise free and noisy situations using the Nonsense syllable Test (NST) was investigated in 5 normal hearing subjects under simulated hearing-impairment. The fricative consonants of English language in CV context were being processed for consonant-vowel intensity ratio modifications from 0 to +12 dB at +3 dB step. The Speech Perception In Noise (SPIN) tests were quantified in terms of information transmission analysis measures, in the presence of white noise-masker at three noise levels,0 dB, +12 dB, and +6 dB. C/V intensity ratio modifications of +6, to +12 dBs were found to improve speech intelligibility in simulated low level sensorineural loss. A maximum intelligibility benefit of 21% points was reported for +12 dB C/V modification, also the perception of consonant place of articulation reported better improvement of intelligibility compared to consonant voicing.