Intelligibility of interrupted sentences at subsegmental levels in young normal-hearing and elderly hearing-impaired listeners

Abstract

Although listeners can partially understand sentences interrupted by silence or noise, and their performance depends on the characteristics of the glimpses, few studies have examined effects of the types of segmental and subsegmental information on sentence intelligibility. Given the finding of twice better intelligibility from vowel-only glimpses than from consonants ͓Kewley-Port et al. ͑2007͒. "Contribution of consonant versus vowel information to sentence intelligibility for young normal-hearing and elderly hearing-impaired listeners," J. Acoust. Soc. Am. 122, 2365-2375͔, this study examined young normal-hearing and elderly hearing-impaired ͑EHI͒ listeners' intelligibility of interrupted sentences that preserved four different types of subsegmental cues ͑steady-states at centers or transitions at margins; vowel onset or offset transitions͒. Forty-two interrupted sentences from TIMIT were presented twice at 95 dB SPL, first with 50% and second with 70% of sentence duration. Compared to high sentence intelligibility for uninterrupted sentences, interrupted sentences had significant decreases in performance for all listeners, with a larger decrease for EHI listeners. Scores for both groups were significantly better for 70% duration than for 50% but were not significantly different for the type of subsegmental information. Performance by EHI listeners was associated with their high-frequency hearing thresholds rather than with age. Together with previous results using segmental interruption, preservation of vowels in interrupted sentences provides greater benefit to sentence intelligibility compared to consonants or subsegmental cues.

Contributions of cochlea-scaled entropy and consonant-vowel boundaries to prediction of speech intelligibility in noise

“…No such duration constraint on the M-level segmentation was imposed in this study. We believe this might account for the discrepancy on the role of C-V boundaries for intelligibility prediction between the present study and the study by Lee and Kewley-Port (2009). Further studies are warranted to assess the effect of segment duration (containing C-V boundaries) to intelligibility prediction.…”

“…This same vocalic segment, however, was classified as an H-level segment and not as an M-level segment. Lee and Kewley-Port (2009) recently examined the intelligibility of interrupted sentences (using the noise-replacement paradigm) preserving four different types of sub-segmental cues, namely steady-state cues at centers or transitions of vowel-consonant margins, and vowel onset or offset transitions. They found that intelligibility scores were not significantly different among the various types of sub-segmental information used.…”

“…To some extent, this differs with the finding of the present study on the contribution of C-V boundaries for intelligibility prediction. The duration of sub-segmental cues in Lee and Kewley-Port (2009), however, was constrained to be 50% or 70% of sentence duration. No such duration constraint on the M-level segmentation was imposed in this study.…”

Cochlea-scaled entropy, not consonants, vowels, or time, best predicts speech intelligibility

“…This explanation depends, however, on vowel and vowel-like sounds being amply kinematic to convey substantial change. In fact, contrary to customary consideration of vowels as being "quasistationary" (13), frequencies of vowel formants in North American English change substantially over time with the exception of high vowels /i/ and /u/ (31, 32). In studies concerning limited classes of speech sounds, some investigators have been drawn to the significance of spectral change for perception [e.g., formant transitions for Cs (33), Vs (31), or CVCs (9)].…”

“…On average, "vowel" segments of sentence waveforms are roughly one-third longer than "consonant" segments in American English. Very recently, Kewley-Port and colleagues (13) provided evidence that there may be no intelligibility differences between replacing consonants (Cs), vowels (Vs), or transitions (CVs, VCs) after accounting for duration.…”