INTRASPEECH SPREAD OF MASKING IN NORMAL-HEARING AND HEARING-IMPAIRED LISTENERS

Hearing-impaired and normal-hearing listeners labeled synthetic conson ant-vowel stimuli (/ba/, /da/, /ga/, /be/, /de/, /ge/) presented at mo derate and high signal levels. First formant (F1) regions were synthes ized at normal and at attenuated levels to test whether F1 attenuation might reduce upward spread of masking, making information contained i n higher formant regions more available. Performance was tested in qui et and in broadband noise sufficient to mask initial release bursts. A lthough complete removal of F1 consistently reduced performance, F1 at tenuation of up to 18 dB led to increased labeling accuracy, particula rly in the /a/ vowel context. Benefit associated with F1 attenuation w as more consistently seen for hearing-impaired than for normal-hearing listeners and, in particular, for Listeners with steep increases in a udiometric thresholds between the first and second formant regions of the test stimuli. The availability of initial bursts as a source of pl ace cues during testing in quiet did not reduce the benefit associated with F1 attenuation.