Temporal Intraspeech Masking of Plosive Bursts: Effects of Hearing Loss and Frequency Shaping

Abstract

PURPOSE-The purposes were 1) to compare masking of consonant bursts by adjacent vowels for listeners with and without hearing loss and 2) to determine the extent to which the "temporal intraspeech masking" can be reduced by a simulated hearing aid frequency-response shaping.METHOD-Fourteen adults with sensorineural hearing loss and six with normal hearing served as participants. Seven of the participants with hearing loss had flat/gradually sloping audiograms and seven had steeply sloping losses. Stimuli consisted of three consonant bursts (/t/, /p/, /k/) presented in isolation and in vowel-consonant-vowel combinations using the vowel /a/ with formant transition information removed. Normal-hearing listeners were tested using unfiltered stimuli. Listeners with hearing loss were tested using unfiltered stimuli and stimuli filtered to approximate a hearing aid frequency response prescribed by NAL-R. All listeners were tested under earphones at the most comfortable level for the vowel stimulus. Temporal intra-speech masking was quantified as the threshold shift produced by the adjacent vowels.RESULTS-Average intra-speech masking for listeners with steeply sloping hearing loss was significantly higher than that of normal-hearing listeners and those with flat/gradually sloping losses. Greater intra-speech masking was observed for /t/ and /p/ than for /k/. On average, frequency shaping significantly reduced the amount of intra-speech masking for listeners with steeply sloping hearing losses. Even with appropriate amplification/spectral shaping, however, temporal intra-speech masking remained greater than normal for several individuals.CONCLUSIONS-Finding suggest that some individuals with steeply sloping losses may need additional signal processing to supplement frequency-shaping in order to overcome the effect of temporal intra-speech masking.Intra-speech masking refers to the interference in the perception of speech cues by components of the speech signal itself. Intra-speech masking has typically been examined using synthesized vowels by measuring the perception of the second formant (F2) with reductions in the level of the first formant (F1) (Danaher et al., 1973;Van Tasell, 1980;Dorman et al., 1985a;Summers & Leek, 1997). Several of these studies demonstrated that attenuation of F1 can improve the audibility and discriminability of F2 transitions (Hannley & Dorman, 1983;Summers & Leek, 1997;Van Tasell, 1980). The studies noted above examined simultaneous intra-speech masking, that is, masking that occurs within simultaneous components of a speech signal. There is some evidence to suggest, however, that temporal masking between sequential speech cues can also influence perception. A number of studies have examined the influence of silence duration on the perception of intervocalic stop consonants in listeners with and without sensorineural hearing loss. Generally, as the silence duration is decreased, listeners become less accurate at labeling plosives on a voicing continuum (Lisker, 1957 (Cazals & Palis, 1...

High-Frequency Sensorineural Hearing Loss Alters Cue-Weighting Strategies for Discriminating Stop Consonants in Noise

“…However, another set of studies based on natural speech sounds has instead highlighted the key role of prevocalic bursts in stop consonant perception (Kapoor & Allen, 2012; Li et al., 2010; Li & Allen, 2011; Mackersie, 2007; Ohde & Stevens, 1983; Summers & Leek, 1997). Kapoor and Allen suggest that these bursts constitute a primary cue for correctly identifying /t/, /d/, /g/, and /b/.…”

Object-based attention modulates the discrimination of level increments in stop-consonant noise bursts

“…While the acoustic evidence is ample and solid, much less is known about the perceptual significance of such increments and more specifically about the differential sensitivity to increments in the burst level or the accuracy with which they are discerned [ 6 ]. Determining perceptual significance is important because, by being much briefer and lower in level than the immediately preceding or following vowels, the stop-consonant noise bursts are less audible and vulnerable to intra-speech or context interference such as temporal masking [ 7 ] that degrades the bursts perceptual analysis. Owing to this interference, the perceptual significance of burst-level differences is not equivalent to the acoustic one, and the discordance between perceptual and acoustic magnitude is not fully understood.…”

“…To characterize differential sensitivity for level increments (∆L) in the pre- (Cv) or post-vocalic (vC) stop-consonant noise bursts of CvC words, we studied how the LDTs depend on four factors. a) The presentation format of the noise bursts, whether in isolation (i.e., excerpted from the CvC) or in word context, in order to unveil context interference [ 7 ]. b) The temporal position, pre- (Cv) or post-vocalic (vC), of the burst with ∆L.…”