Effortful Listening: The Processing of Degraded Speech Depends Critically on Attention

Abstract

The conditions of everyday life are such that people often hear speech that has been degraded (e.g., by background noise or electronic transmission) or when they are distracted by other tasks. However, it remains unclear what role attention plays in processing speech that is difficult to understand. In the current study, we used functional magnetic resonance imaging to assess the degree to which spoken sentences were processed under distraction, and whether this depended on the acoustic quality (intelligibility) of the speech. On every trial, adult human participants attended to one of three simultaneously presented stimuli: a sentence (at one of four acoustic clarity levels), an auditory distracter, or a visual distracter. A postscan recognition test showed that clear speech was processed even when not attended, but that attention greatly enhanced the processing of degraded speech. Furthermore, speech-sensitive cortex could be parcellated according to how speech-evoked responses were modulated by attention. Responses in auditory cortex and areas along the superior temporal sulcus (STS) took the same form regardless of attention, although responses to distorted speech in portions of both posterior and anterior STS were enhanced under directed attention. In contrast, frontal regions, including left inferior frontal gyrus, were only engaged when listeners were attending to speech and these regions exhibited elevated responses to degraded, compared with clear, speech. We suggest this response is a neural marker of effortful listening. Together, our results suggest that attention enhances the processing of degraded speech by engaging higher-order mechanisms that modulate perceptual auditory processing.

Cognitive predictors of perceptual adaptation to accented speech

“…To our knowledge, ours is the first study to directly link inhibition to perceptual adaptation to accented speech. This finding adds to a growing body of evidence that executive function, such as inhibition or attention, has a major role in perceptual adaptation to unfamiliar speech (Huyck and Johnsrude, 2012;Wild et al, 2012;Erb et al, 2013), including adaptation to accented speech (Adank and Janse, 2010;Janse and Adank, 2012). Inhibitory abilities are likely recruited when competing (and incorrect) lexical responses are triggered by the accented speech (Brouwer et al, 2012;Tuinman et al, 2012), thus helping to resolve ambiguities in the speech signal.…”

“…Executive function has been defined as cognitive processes, such as inhibitory mechanisms, that help control and coordinate other aspects of cognition, and is associated with activity in the frontal lobe (e.g., Miyake et al, 2000). Neuroimaging studies have revealed activity in cortical regions associated with executive function when processing degraded compared with clear speech (Wild et al, 2012;Erb et al, 2013), while behavioral studies have demonstrated that attentional mechanisms are recruited for perceptual adaptation in lower level auditory training (Halliday et al, 2011), and higher level adaptation to noise-vocoded (Huyck and Johnsrude, 2012), frequencycompressed (Ellis and Munro, 2013), and accented speech (Adank and Janse, 2010;Janse and Adank, 2012). However, it is unclear exactly how executive functions contribute to perceptual adaptation.…”

The Moderating Effect of Success Importance on the Relationship Between Listening Demand and Listening Effort

“…XXXX; Kuchinsky et al 2013;Piquado et al 2010;Zekveld & Kramer 2014;Zekveld et al 2010), heart rate, skin conductance, skin temperature, EMG activity (e.g., Mackersie & Cones 2011), heart rate variability (e.g., Mackersie & Calderon-Moultrie, this issue, pp. XXXX), fMRI activity (Wild et al 2012), ERPs (Obleser & Kotz 2011), and EEG alpha power (Obleser et al 2012) (see McGarrigle et al 2014, for a summary of listening effort studies using physiological measures published between 2008 and 2013). A common element of these psychophysiological studies on listening effort is that they examined the effects of variables related to listening difficulty on the physiological measures of interest.…”

Predictive processing increases intelligibility of acoustically distorted speech: Behavioral and neural correlates

“…However, the strategies of the human brain to resolve semantic content of speech may differ under acoustically optimal and suboptimal conditions. Indeed, contradicting the hierarchical model of speech comprehension, activity in the primary auditory cortex has been shown to reflect speech intelligibility when speech is acoustically distorted (Wild et al., 2012b). Furthermore, speech comprehension specifically in acoustically adverse conditions has been associated with several brain areas including the left inferior frontal gyrus (Clos et al., 2014; Giraud et al., 2004; Hervais‐Adelman et al., 2012; Obleser & Kotz, 2010; Obleser, Wise, Dresner, & Scott, 2007; Shahin, Bishop, & Miller, 2009; Wild et al., 2012a), the anterior cingulate cortex (Erb, Henry, Eisner, & Obleser, 2012; Giraud et al., 2004), the anterior insula (Adank, 2012; Erb, Henry, Eisner, & Obleser, 2013; Giraud et al., 2004; Hervais‐Adelman et al., 2012; Shahin et al., 2009), the middle frontal gyrus (Giraud et al., 2004; Sohoglu et al., 2012), and the supplementary motor cortex (Adank, 2012; Erb et al., 2013; Hervais‐Adelman et al., 2012; Shahin et al., 2009).…”