Speaker-induced Suppression in EEG during a Naturalistic Reading and Listening Task

Abstract

Speaking elicits a suppressed neural response when compared with listening to others' speech, a phenomenon known as speaker-induced suppression (SIS). Previous research has focused on investigating SIS at constrained levels of linguistic representation, such as the individual phoneme and word level. Here, we present scalp EEG data from a dual speech perception and production task where participants read sentences aloud then listened to playback of themselves reading those sentences. Playback was separated into immediate repetition of the previous trial and randomized repetition of a former trial to investigate if forward modeling of responses during passive listening suppresses the neural response. Concurrent EMG was recorded to control for movement artifact during speech production. In line with previous research, ERP analyses at the sentence level demonstrated suppression of early auditory components of the EEG for production compared with perception. To evaluate whether linguistic abstractions (in the form of phonological feature tuning) are suppressed during speech production alongside lower-level acoustic information, we fit linear encoding models that predicted scalp EEG based on phonological features, EMG activity, and task condition. We found that phonological features were encoded similarly between production and perception. However, this similarity was only observed when controlling for movement by using the EMG response as an additional regressor. Our results suggest that SIS operates at a sensory representational level and is dissociated from higher order cognitive and linguistic processing that takes place during speech perception and production. We also detail some important considerations when analyzing EEG during continuous speech production.

Processing of auditory feedback in perisylvian and insular cortex

“…In other words, an electrode that encodes plosive voiced obstruents (like /b/, /g/, /d/) during speech perception will still encode plosive voiced obstruents during speaker-induced suppression, but the amplitude of the response is reduced during speaking. This is consistent with similar research in scalp EEG conducted by our group (Kurteff et al, 2023) and supports the confinement of cortical suppression during speech production strictly to lower-level sensory components of the auditory system. This is also in line with previous literature showing the degree of suppression observed at an individual utterance is dependent on that utterance’s adherence to a sensory goal (Niziolek et al, 2013).…”

“…In temporal cortex, proximal to where onset responses have been previously identified using surface electrocorticography (Hamilton et al, 2018), we observed a selective suppression of transient responses to sentence onset during speech production, whereas sustained responses remained relatively unchanged between speech perception and production. The timing of the suppressed onset responses is roughly aligned with scalp-based studies of speaker-induced suppression that posit early components (N1 for EEG, M1 for MEG) as biomarkers of speaker-induced suppression (Hawco et al, 2009;Heinks-Maldonado et al, 2006;Kurteff et al, 2023;Martikainen et al, 2005). While we do not claim the onset responses observed in our study and others to be equivalent to N/M100, there is a parallel to be drawn between the temporal characteristics of our suppressed cortical activity and the deep literature on suppression of these components during speech production in noninvasive studies.…”

“…We interpret this response profile as indicative of feedback enhancement for the purposes of speech motor control during speech production. This playback consistency manipulation was also included in a recently published EEG version of this task (Kurteff et al, 2023), but the results of the manipulation were inconclusive. In that EEG study, however, we did see cortical suppression at sentence onset, so perhaps the lack of a result for the consistency manipulation is a mixture of the relatively smaller effect size of the consistency manipulation and the lower signal-to-noise ratio of scalp EEG recordings in comparison to intracranial EEG.…”

“…Recent research from our group used scalp EEG recordings to demonstrate that responses to continuous sentences are suppressed during production compared to perception of those same sentences while phonological tuning remains unchanged (Kurteff et al, 2023). However, such conclusions may be tempered by the low spatial resolution of scalp recordings, motivating the use of high-resolution intracranial stereo EEG (sEEG) recordings.…”

Bridging verbal coordination and neural dynamics

“…Thereby, the decrease in high-frequency activity as speech coordination increases could be explained by the closer correspondence between the speech signal perceived from the VP and that produced by the patient. This phenomenon has been previously described as speaker-induced suppression (SIS), characterised by a suppression of the neural response corresponding to the speech signal of one’s own voice compared to the speech signals of others (Niziolek et al 2013 ; Kurteff et al, 2023). In the present task, auditory feedback from the on-going speech stream is used to maintain fluent speech production.…”