Sentence intelligibility during segmental interruption and masking by speech-modulated noise: Effects of age and hearing loss

Abstract

This study investigated how single-talker modulated noise impacts consonant and vowel cues to sentence intelligibility. Younger normal-hearing, older normal-hearing, and older hearing-impaired listeners completed speech recognition tests. All listeners received spectrally shaped speech matched to their individual audiometric thresholds to ensure sufficient audibility with the exception of a second younger listener group who received spectral shaping that matched the mean audiogram of the hearing-impaired listeners. Results demonstrated minimal declines in intelligibility for older listeners with normal hearing and more evident declines for older hearing-impaired listeners, possibly related to impaired temporal processing. A correlational analysis suggests a common underlying ability to process information during vowels that is predictive of speech-in-modulated noise abilities. Whereas, the ability to use consonant cues appears specific to the particular characteristics of the noise and interruption. Performance declines for older listeners were mostly confined to consonant conditions. Spectral shaping accounted for the primary contributions of audibility. However, comparison with the young spectral controls who received identical spectral shaping suggests that this procedure may reduce wideband temporal modulation cues due to frequency-specific amplification that affected high-frequency consonants more than low-frequency vowels. These spectral changes may impact speech intelligibility in certain modulation masking conditions.

The intelligibility of interrupted and temporally altered speech: Effects of context, age, and hearing loss

“…Subsequent to compression, the sentences were interrupted by either gating with silence or with noise at six interruption rates: 0.625, 1.25, 2.5, 5, 10, and 20 Hz. As in other research with interrupted speech (Kidd and Humes, 2010;Molis et al, 2015;Shafiro et al, 2015;Fogerty et al, 2015), young adults outperformed older listeners overall. Sentences interrupted with noise were considerably more intelligible than those interrupted with silence.…”

Glimpsing Speech in the Presence of Nonsimultaneous Amplitude Modulations From a Competing Talker: Effect of Modulation Rate, Age, and Hearing Loss

“…For many individuals with hearing loss, hearing aids provide amplification in the higher frequencies to ensure audibility of the full speech spectrum (Humes, 2007). However, such spectral shaping of the speech can reduce temporal modulation cues, which may affect speech recognition in temporally complex listening conditions (Fogerty, Ahlstrom, Bologna, & Dubno, 2015). To further address this question, the current investigation included a second group of younger listeners with normal hearing who listened to speech that was spectrally shaped according to the average audiogram of the listeners with impaired hearing and that was presented at the same sound-pressure level.…”

“…Spectral shaping, while effective at increasing speech audibility for OHI listeners and minimizing audibility differences across groups (Humes, 2013), might limit the benefit in temporally complex conditions due to altered acoustic signals. For example, spectral shaping reduces the amplitudemodulation depth (i.e., consonant-vowel intensity ratio) of the broadband speech signal by amplifying high-frequency, low-intensity consonants (see also Fogerty et al, 2015). In addition, listeners' unfamiliarity with the spectrally shaped stimulus may have resulted in a perceptual mismatch with stored mental representations of speech (Rönnberg et al, 2013), leading to poorer scores.…”

Simultaneous and forward masking of vowels and stop consonants: Effects of age, hearing loss, and spectral shaping

“…With regard to vowels, vowel perception in noise by younger adults with normal hearing is likely better than consonant perception in noise, due to longer and more intense vowel cues compared to the shorter, low-level cues of obstruent consonants (Blumstein and Stevens, 1979;Kewley-Port et al, 1983). Access to the slow, periodic fluctuations of vowels may also benefit vowel perception in temporally complex noise (e.g., Fogerty et al, 2015). However, aging appears to negatively affect the ability to use these cues for vowel perception.…”