Effect of a single-channel wide dynamic range compression circuit on perception of stop consonant place of articulation

Previous studies have shown that altering the amplitude of a consonant in a specific frequency region relative to an adjacent vowel's amplitude in the same frequency region will affect listeners' perception of the consonant p lace of articulation. Hearing aids with single-channel, fast-acting wide dy namic range compression (WDRC) alter the overall consonant-vowel (CV) inten sity ratio by increasing consonant energy. Perhaps one reason WDRC has had limited success in improving speech recognition performance is that the nat ural amplitude balances between consonant and vowel are altered in crucial frequency regions, thus disturbing the aforementioned amplitude cue For det ermining place of articulation. The current study investigated the effect o f a WDRC circuit on listeners' perception of place of articulation when the relative amplitude of consonant and vowel was manipulated. The stimuli wer e a continuum of synthetic CV syllables stripped of all place cues except r elative consonant amplitudes. Acoustic analysis of the CVs before and after hearing aid processing showed a predictable increase in high-frequency ene rgy, particularly For the burst of the consonant. Alveolar bursts had more high-frequency energy than labial bursts. Twenty-five listeners with normal hearing and 5 listeners with sensorineural hearing loss labeled the conson ant sound of the CV syllables in unaided Form and after the syllables were recorded through a hearing aid with single-channel WDRC. There were signifi cantly more listeners who were unable to produce a category boundary when l abeling the aided stimuli. OF those listeners who did yield a category boun dary for both aided and unaided stimuli, there were significantly more alve olar responses for the aided condition. These results can be explained by t he acoustic analyses of the aided stimuli.