Cognitive load makes speech sound fast, but does not modulate acoustic context effects

Abstract

a b s t r a c tIn natural situations, speech perception often takes place during the concurrent execution of other cognitive tasks, such as listening while viewing a visual scene. The execution of a dual task typically has detrimental effects on concurrent speech perception, but how exactly cognitive load disrupts speech encoding is still unclear. The detrimental effect on speech representations may consist of either a general reduction in the robustness of processing of the speech signal ('noisy encoding'), or, alternatively it may specifically influence the temporal sampling of the sensory input, with listeners missing temporal pulses, thus underestimating segmental durations ('shrinking of time'). The present study investigated whether and how spectral and temporal cues in a precursor sentence that has been processed under high vs. low cognitive load influence the perception of a subsequent target word. If cognitive load effects are implemented through 'noisy encoding', increasing cognitive load during the precursor should attenuate the encoding of both its temporal and spectral cues, and hence reduce the contextual effect that these cues can have on subsequent target sound perception. However, if cognitive load effects are expressed as 'shrinking of time', context effects should not be modulated by load, but a main effect would be expected on the perceived duration of the speech signal. Results from two experiments indicate that increasing cognitive load (manipulated through a secondary visual search task) did not modulate temporal (Experiment 1) or spectral context effects (Experiment 2). However, a consistent main effect of cognitive load was found: increasing cognitive load during the precursor induced a perceptual increase in its perceived speech rate, biasing the perception of a following target word towards longer durations. This finding suggests that cognitive load effects in speech perception are implemented via 'shrinking of time', in line with a temporal sampling framework. In addition, we argue that our results align with a model in which early (spectral and temporal) normalization is unaffected by attention but later adjustments may be attention-dependent.Ó 2016 Elsevier Inc. All rights reserved. IntroductionSpeech perception is most commonly studied under ideal listening conditions that allow participants to dedicate their full attention to the listening task at hand. However, natural conversations typically take place in a world http://dx

Biasing the perception of spoken words with tACS

“…We used a tACS montage targeting auditory cortices (Riecke, Sack, and Schroeder 2015;, suggesting that the observed effect occurs in auditory cortical areas involved in speech processing. This notion is corroborated by findings showing that phonological information may be decoded from early auditory oscillatory activity (Di Liberto, O'Sullivan, and Lalor 2015;Ten Oever and Sack 2015), and that behavioral perceptual biases induced by fast vs. slow speech rhythms arise early in perception (Maslowski, Meyer, and Bosker 2019) and independently from attention (Bosker, Reinisch, and Sjerps 2017). Our results show no significant effect of tACS phase on vowel perception.…”

Listening to yourself is special: Evidence from global speech rate tracking

“…Context effects have furthermore been shown to hold even for 2–4 months old infants [26] and non-human species [27]. Lastly, effects of adjacent rate contexts are unaffected by attentional modulation, which supports the involvement of early perceptual processes [28]. …”

Entrained theta oscillations guide perception of subsequent speech: behavioural evidence from rate normalisation

“…in English, short /b/ vs. long /w/; in Dutch, short /ɑ/ vs. long /a:/) may be biased towards the longer phoneme (i.e. /w/ in English; /a:/ in Dutch) if presented after a preceding sentence (hereafter: carrier) produced at a faster speech rate (Bosker, Reinisch, & Sjerps, 2017;Kidd, 1989;Pickett & Decker, 1960;Reinisch & Sjerps, 2013;Toscano & McMurray, 2015). This process, known as rate normalisation, has been argued to involve generalauditory processes, since it occurs in human and nonhuman species (Dent, Brittan-Powell, Dooling, & Pierce, 1997), is induced by talker-incongruent contexts (Bosker, 2017b;Newman & Sawusch, 2009), and even by non-speech (Bosker, 2017a;Gordon, 1988;Wade & Holt, 2005); in contrast to other rate-dependent perceptual effects, such as the Lexical Rate Effect (Dilley & Pitt, 2010;Pitt, Szostak, & Dilley, 2016).…”