Sally G. Revoile

Perceptual cues to the voiced–voiceless distinction of final fricatives for listeners with impaired or with normal hearing

Cues to the voicing distinction for final /f,s,v,z/ were assessed for 24 impaired- and 11 normal-hearing listeners. In base-line tests the listeners identified the consonants in recorded /d circumflex C/ syllables. To assess the importance of various cues, tests were conducted of the syllables altered by deletion and/or temporal adjustment of segments containing acoustic patterns related to the voicing distinction for the fricatives. The results showed that decreasing the duration of /circumflex/ preceding /v/ or /z/, and lengthening the /circumflex/ preceding /f/ or /s/, considerably reduced the correctness of voicing perception for the hearing-impaired group, while showing no effect for the normal-hearing group. For the normals, voicing perception deteriorated for /f/ and /s/ when the frications were deleted from the syllables, and for /v/ and /z/ when the vowel offsets were removed from the syllables with duration-adjusted vowels and deleted frications. We conclude that some hearing-impaired listeners rely to a greater extent on vowel duration as a voicing cue than do normal-hearing listeners.

VCVs vs CVCs for stop/fricative distinctions by hearing‐impaired and normal‐hearing listeners

Moderately to profoundly hearing-impaired (n = 30) and normal-hearing (n = 6) listeners identified [p, k, t, f, theta, s] in [symbol; see text], and [symbol; see text]s tokens extracted from spoken sentences. The [symbol; see text]s were also identified in the sentences. The hearing-impaired group distinguished stop/fricative manner more poorly for [symbol; see text] in sentences than when extracted. Further, the groups performance for extracted [symbol; see text] was poorer than for extracted [symbol; see text] and [symbol; see text]. For the normal-hearing group, consonant identification was similar among the syllable and sentence contexts.

Nonlinear Distortion and Battery Life in Hearing Aids

This study examined the alterations in nonlinear distortion in hearing aids that resulted from normal battery‐voltage variations over useable battery life. New hearing aids of several types were selected for study. Initially, the gain of each instrument was adjusted to a level 6 dB below maximum at 1000 Hz. The gain was readjusted to this value for all subsequent measurements until battery voltage dropped below a level adequate to maintain that gain, even at a maximum setting. Nonlinear distortion was recorded at 500, 600, 700, 900, and 1250 Hz, utilizing 70‐dB‐SPL (sound‐pressure level) input signals. The hearing aids were operated for 8 h daily and distortion measurements were made at regular intervals until gain dropped below −10 dB reference the initial test value. The results indicate that for some hearing‐aid/battery‐type combinations disproportionate increases in distortion accompany decreases in battery life. Results are considered both as a function of battery life and voltage. Implications of th...

Perception of prosodic phrasing by hard‐of‐hearing listeners

Severely to profoundly hard‐of‐hearing (HOH) listeners (n=12) were tested for their perception of prosodic phrase continuity in clear and conversational speech. In two experiments, fluently spoken sentences were compared with utterances artificially assembled from isolated words (experiment 1) and prosodic phrases (experiment 2) that replicated the sentences’ lexical composition. The difference in the overall duration of the assembled and fluent utterance was eliminated via signal processing, but the amplitude envelope and the intonational contour differences were left intact. Randomized repetitions of each utterance pair (72 pairs, 12 sentences × 2 speaking styles × 3 speakers, in experiment 1, and 40 pairs, 10 sentences × 2 speaking styles × 2 speakers, in experiment 2) were presented to each listener over several experimental sessions. In a 2IFC procedure, the listener identified the utterance that sounded more like fluent speech. Four normal‐hearing (NH) controls were tested in white noise (S/N ratio=...

Enhancing second formant identification in speech by listeners with significant hearing loss

Listeners with significant hearing loss have consonant recognition abilities that appear limited by their inability to use spectral peak information in the higher frequencies, specifically in the highly informative second formant (F2) frequency region. For them, ensuring the audibility of speech may not result in full recognition of consonants and vowels that differ by F2 characteristics. In the current study, listeners with moderate to severe hearing loss identified naturally spoken consonant‐vowel‐consonant stimuli (CVCs) with a wide range of F2/F1 formant frequency characteristics at levels that ensured the audibility of the F2 region. CVCs were presented in three conditions: (a) unmodified, (b) filtered to enhance the F1 and F2 regions, and (c) frequency‐modulated to transpose the F2 peak to a lower, more detectable frequency region. The amount of modulation for condition (c) was determined by measuring individual spectral peak detection thresholds for each listener using the rippled‐noise method desc...

Detection and discrimination of spectral peaks by listeners with moderate to severe hearing losses

Summers and Leek (1994) demonstrated that listeners with moderate hearing loss have a reduced ability to identify spectral peaks in broadband stimuli coincident with increased auditory filter bandwidths, but that abilities were presumed sufficient for vowel identification. The current study investigated spectral ripple detection and ripple frequency discrimination with listeners having moderate and severe losses. Stimuli were flat spectrum pure‐tone complexes log‐spaced over 2‐oct bands (1000–4000 Hz and 500–2000 Hz). In one experiment the different signal’s spectrum was multiplied by sinusoidal log‐spaced ripples. Ripple frequency was held constant while ripple amplitude adapted. In the second experiment, all signals contained constant‐amplitude ripples with ripple frequency adapting. Preliminary results for moderate loss listeners indicate ripple detection thresholds for both 2‐oct band stimuli are similar to those previously reported. Comparatively, listeners with flat severe losses have markedly poore...

Lexical stress perception by hearing‐impaired listeners.

Identification of lexical stress in VCVs isolated from sentences was studied for moderately to profoundly hearing‐impaired listeners. Two factors, sentential stress position and speech rate, were manipulated separately in the production of ‘‘You put VCV to bed.’’ When sentential stress was manipulated, each of: you, put, VCV, bed, was stressed. When speech rate (fast and slow) was manipulated, the VCVs were from sentences with stress on the VCV only. Twenty VCVs for each speech rate and ten VCVs for each sentential stress position were tested. Hearing‐impaired (n=33) and normal‐hearing listeners (n=8) identified whether the VC or the CV was stressed. In contrast to the normal‐hearing listeners, lexical stress identification by the hearing‐impaired listeners was significantly reduced for the fast speech rate. Both listener groups showed the same effect of sentential stress location: Performance was best when emphasis was on the VCV, and worst when either constituent adjacent to the VCV was emphasized. Results will be discussed with reference to the acoustic consequences of the production constraints and the accessibility of the prosodic cues to the hearing‐impaired subjects as predicted by several audiological and psychoacoustic variables. [Work supported by NIH and the Gallaudet Research Institute.]

Stress identification by hearing‐impaired listeners

Some acoustic correlates of stress perception were studied for listeners with moderate to profound hearing loss. The sentence ‘‘You put VCV to bed’’ was spoken with emphasis on each of the main constituents (you, put, VCV, to bed) respectively, yielding four stress contexts. For each stress context, ten different sentence utterances were tested. The sentences were modified acoustically to neutralize the temporal and/or amplitude prominence of the stressed word. Hearing‐impaired (n=22) and normal‐hearing listeners (n=8) identified the stressed word for the modified and unmodified sentences. Contrary to the performance in normal‐hearing listeners, stress perception by the hearing‐impaired listeners was significantly reduced when both amplitude and temporal characteristics of the stressed word were modified. Less of an effect occurred when only amplitude or temporal characteristics alone were neutralized. Results are discussed with reference to the extent and rate of F0 change across the sentence for the four stress contexts, and the accessibility of the intonational cues to the hearing impaired subjects as predicted by several audiological and psychoacoustic variables. [Work supported by NIH.]

Toward understanding the role of formant transitions for distinctions of stops from glides

Our understanding is incomplete of the properties of vowel formant transitions that contribute to distinctions of voiced stop and glide consonants in speech. Research appears to have established some of the important transition cues for discernment of bilabial synthetic stops versus glides. However, the stop/glide transitions studied have typically been more stylized than those found in natural speech. This investigation examined the importance of transitions to listeners’ identification of initial stops and glides in spoken /CVk/ syllables. Performance was assessed for the stops and glides with progressive deletion of segments from the syllables’ onsets. Bilabial and velar stops and glides as well as alveolar stops were tested in /Ci/, /Copen ayek/, /Cash, ligaturek/ contexts to examine differences in transition use among phoneme environments. Twelve normal‐hearing young adults participated as listeners. In general, when the initial stop bursts were deleted, the F2 transition frequency extent was signifi...

Predicting hearing‐impaired listeners’ use of acoustic cues for consonant recognition

Reduced consonant recognition and large inter‐listener variability among individuals with sensorineural hearing loss are neither well characterized nor understood. Previous attempts to account for consonant recognition using threshold and suprathreshold measures have produced equivocal results. Classifications of listeners according to performance patterns for acoustic cue use are lacking. The present study classifies hearing‐impaired listeners according to their use of information in successive vowel and consonant segments for identification of consonants. Seventy hearing‐impaired (moderate to profound) and 19 normal‐hearing listeners identified /n/, /l/, and /d/ in spoken VCV’s extracted from connected speech. The VCV’s were presented unmodified and with consonant and vowel‐transition segment deletions. Percent information transmitted scores for each consonant and stimulus condition were submitted to a hierarchical cluster analysis to classify all listeners into homogeneous groups based on the extent to...