Intelligibility of Temporally Interrupted Speech with and without Intervening Noise

Abstract

A previous investigation [G. R. Miller and J. C. R. Licklider, J. Acoust. Soc. Amer. 22, 167–173 (1950)] reported that intelligibility of interrupted monosyllabic words was essentially equal in the presence and absence of intervening noise when speech-time fraction was 0.5 and switching rates were approximately below five interruptions per second (ips). Two experiments investigated the effect upon intelligibility of temporally interrupted C. I. D. sentences [S. R. Silverman and I. J. Hirsh, Ann. Otol. Rhinol. Laryngol. 64, 1234–1245 (1955)] when noise was introduced during the speech-free interval. In study 1, listeners received the test material under two conditions at five interruption rates ranging from 0.77 to 3.85 ips. In one instance the speech-free interval was silent; in the other it was switched to white noise of the same average level as the speech. Speech-time fraction was 0.5. Study 2 examined the intelligibility of the interrupted sentences as a function of noise level present during the speech-free interval. The switching condition was held constant and signal-to-noise ratio varied from +9 to −15 dB. Results indicate that for the particular interruption conditions selected, speech switched to noise was significantly more intelligible than speech interrupted in the silence. In addition, listener performance depends upon the level of noise present during the speech-free interval.

Illusory Vowels Resulting from Perceptual Continuity: A Functional Magnetic Resonance Imaging Study

“…Over the last few decades, the continuity illusion has been extensively studied in behavioral experiments using a variety of stimuli, including pure and modulated tones, tone glides, and speech (Carlyon, Micheyl, Deeks, & Moore, 2002;Warren, Wrightson, & Puretz, 1988;Ciocca & Bregman, 1987;Powers & Wilcox, 1977;Houtgast, 1972;Warren, Obusek, & Ackroff, 1972;Vicario, 1960;Miller & Licklider, 1950). The results of all these studies have led to a firm understanding of the stimulus parameters that do and do not lead to a percept of illusory continuity.…”

Comparing human and automatic speech recognition in a perceptual restoration experiment

“…Perceptual restoration studies indicate that the restoration effect depends on acoustic cues that relate to the additive noise (Powers and Wilcox, 1977;Samuel, 1981;Warren et al, 1997) and context cues that relate to the speech material (Warren and Sherman, 1974;Verschuure and Brocaar, 1983;Bashford et al, 1992). The current section describes the stimuli and evaluation metric used in the present work.…”

“…Experiments conducted on human listeners indicate that the perceptual restoration effect depends on the level difference between the speech and additive noise stimuli (Powers and Wilcox, 1977;Warren et al, 1997). For this reason, we determined the average level in each clean speech utterance and scaled the additive-noise levels according to the estimated speech levels.…”

“…This is because additive noise that is much more intense than the removed speech content does not provide acoustic-level cues that would aid restoration, and the observed features cease to constrain the clean speech posterior distribution in Equations (4)-(5). Powers and Wilcox (1977) conducted perceptual restoration experiments using interrupted speech and additive noise at several interruption rates and noise levels. Listener performance at different additive-noise levels was evaluated with 1/3 second interruptions and white noise inserts.…”

“…It therefore appears that perceptual restoration only occurs if there is sufficient evidence that the speech has been masked by additive noise (Bregman, 1990). Furthermore, perceptual restoration is accompanied by a benefit in terms of speech intelligibility; listeners are better able to repeat speech content when additive noise is introduced in the removed portions (Warren, 1984;Verschuure and Brocaar, 1983;Powers and Wilcox, 1977;Warren et al, 1997). Repp (1992) proposed that perceptual restoration theories could be categorised into those based on segregation or top-down completion.…”