Can you hear me now? Musical training shapes functional brain networks for selective auditory attention and hearing speech in noise

Abstract

Even in the quietest of rooms, our senses are perpetually inundated by a barrage of sounds, requiring the auditory system to adapt to a variety of listening conditions in order to extract signals of interest (e.g., one speaker's voice amidst others). Brain networks that promote selective attention are thought to sharpen the neural encoding of a target signal, suppressing competing sounds and enhancing perceptual performance. Here, we ask: does musical training benefit cortical mechanisms that underlie selective attention to speech? To answer this question, we assessed the impact of selective auditory attention on cortical auditory-evoked response variability in musicians and non-musicians. Outcomes indicate strengthened brain networks for selective auditory attention in musicians in that musicians but not non-musicians demonstrate decreased prefrontal response variability with auditory attention. Results are interpreted in the context of previous work documenting perceptual and subcortical advantages in musicians for the hearing and neural encoding of speech in background noise. Musicians' neural proficiency for selectively engaging and sustaining auditory attention to language indicates a potential benefit of music for auditory training. Given the importance of auditory attention for the development and maintenance of language-related skills, musical training may aid in the prevention, habilitation, and remediation of individuals with a wide range of attention-based language, listening and learning impairments.

Keywords: attention; auditory-evoked potentials; cortical variability; language; music; musicians; prefrontal cortex; speech in noise.

Figure 1

Musicians, auditory attention, and processing speech in noise. We assessed auditory attention, speech-in-noise perception and auditory brainstem function in musicians and non-musicians (Parbery-Clark et al., 2009; Strait et al., 2010). Musicians demonstrated enhanced auditory attention as measured by reaction time (A) and were better able to accurately repeat sentences presented in noise at poorer signal-to-noise ratios than non-musicians (B). Auditory attention performance correlated with speech-in-noise perception across all subjects, with individuals having faster reaction times during a sustained attention task demonstrating better hearing in noise (C). Although both musicians and non-musicians demonstrated robust neural responses to a speech sound when presented in a quiet background, non-musicians’ responses were particularly degraded with the addition of a six-talker babble noise to the background. In both groups, the brainstem response waveform is positively correlated with the acoustic waveform of the stimulus. However, when the stimulus is presented in the presence of background noise musicians’ brainstem responses represent the stimulus more faithfully than non-musicians’ (D). *p < 0.05; **p < 0.01.

Figure 2

Impact of attention on cortical auditory-evoked response variability at individual electrode sites. Electrode sites demonstrating a significant decrease in response variability in the attend relative to the ignore condition are in bold black font. Gray italics denote sites that were not subjected to individual analysis. Auditory-evoked activity recorded from PF1/PF2 demonstrated a decrease in variability with attention in musicians only (see Figure 3). ~p < 0.10; *p < 0.05; **p < 0.01; ***p < 0.001.

Figure 3

Cortical auditory-evoked response variability in musicians and non-musicians. (A) 31-Channel headplots for musicians (left) and non-musicians (right) demonstrate the difference in cortical auditory-evoked response variability between ignore and attention conditions, plotting variability across the scalp as a function of attention. Because the difference was calculated by subtracting attend from ignore variability, positive values (red) indicate a decrease in response variability in the attend relative to the ignore condition. Negative values (blue) indicate an increase in response variability in the attend relative to the ignore condition. (B) Musicians demonstrate an increased impact of attention on prefrontal response variability compared to non-musicians. Whereas musicians demonstrate a decrease in prefrontal response variability in the attend relative to the ignore condition, non-musicians do not. **p < 0.01.

Figure 4

Variability in evoked neural activity from intracranial recordings in the cat visual cortex (areas 17 and 18). The local field potential (LFP) and spike discharges of two isolated neurons were simultaneously recorded from a microelectrode in response to repetitive visual stimulation that occurred every 3.5 ms (see Arieli et al., for further information). Variability in neuronal activity can be seen within (A) trial-by-trial LFPs as well as (B) within the spike trains of individual neurons contributing to the LFP.