Recognition of Voiceless Fricatives by Normal and Hearing-Impaired Subjects

Abstract

The purpose of this study was to investigate the sufficient perceptual cues used in the recognition of four voiceless fricative consonants [s, f, θ, ∫] followed by the same vowel [i:] in normal-hearing and hearing-impaired adult listeners. Subjects identified the four CV speech tokens in a closed-set response task across a range of presentation levels. Fricative syllables were either produced by a human speaker in the natural stimulus set, or generated by a computer program in the synthetic stimulus set. By comparing conditions in which the subjects were presented with equivalent degrees of audibility for individual fricatives, it was possible to isolate the factor of lack of audibility from that of loss of suprathreshold discriminability. Results indicate that (a) the frication burst portion may serve as a sufficient cue for correct recognition of voiceless fricatives by normal-hearing subjects, whereas the more intense CV transition portion, though it may not be necessary, can also assist these subjects to distinguish place information, particularly at low presentation levels; (b) hearing-impaired subjects achieved close-to-normal recognition performance when given equivalent degrees of audibility of the frication cue, but they obtained poorer-than-normal performance if only given equivalent degrees of audibility of the transition cue; (c) the difficulty that hearing-impaired subjects have in perceiving fricatives under normal circumstances may be due to two factors: the lack of audibility of the frication cue and the loss of discriminability of the transition cue.

Spectral Distribution of /s/ and the Frequency Response of Hearing Aids

“…Harris ( 1957), for example, concluded that such transitions are important for differentiating /f/ from /th/, but not for identifying /s/ and /sh/. In contrast, both Zeng and Turner ( 1990) and Whalen ( 199 1) have demonstrated a significant contribution of vowel formant transitions to the identification of /s/ by hearing subjects. Zeng and Turner ( 1990), however, found that hearing-impaired subjects could not use these formant transitions, but needed to hear the fricative spectra.…”

Measuring consonant identification in nonsense syllables, words, and sentences

“…As a result, patients with hearing impairment may use different acoustic cues in consonant discrimination [37] and hence might show altered patterns of consonant confusions compared with subjects with normal hearing.…”

Perception of clear fricatives by normal-hearing and simulated hearing-impaired listeners

“…Adult listeners with normal hearing seem to make more use of spectral cues for place of articulation information ͑Heinz and Stevens, 1961;Harris, 1958;Hedrick and Ohde, 1993;Hughes and Halle, 1956;Nittrouer, 1992;Nittrouer and Miller, l997a and 1997b;Nittrouer, 2002;Zeng and Turner, 1990͒, and temporal , 1975;Raphael, 1972;Soli, 1982͒. Hearing-impaired listeners may have difficulty integrating amplitude and spectral cues, and may generally place less weight on formant transitions than listeners with normal hearing ͑Hedrick, 1997; Hedrick and Younger, 2003;Zeng and Turner, 1990͒. In addition, listeners with sloping hearing loss commonly have elevated thresholds, and reduced dynamic range, in regions relevant to fricative perception ͑e.g., Dubno et al, 1982;Owens et al, 1972;Sher and Owens, 1974͒. It is likely, then, that clear speech alternations involving fricative spectra may have different results depending on the listener population.…”