Neurofeedback Training of Auditory Selective Attention Enhances Speech-In-Noise Perception

Subong Kim,Caroline Emory,Inyong Choi

doi:10.3389/fnhum.2021.676992

Abstract

Selective attention enhances cortical responses to attended sensory inputs while suppressing others, which can be an effective strategy for speech-in-noise (SiN) understanding. Emerging evidence exhibits a large variance in attentional control during SiN tasks, even among normal-hearing listeners. Yet whether training can enhance the efficacy of attentional control and, if so, whether the training effects can be transferred to performance on a SiN task has not been explicitly studied. Here, we introduce a neurofeedback training paradigm designed to reinforce the attentional modulation of auditory evoked responses. Young normal-hearing adults attended one of two competing speech streams consisting of five repeating words (“up”) in a straight rhythm spoken by a female speaker and four straight words (“down”) spoken by a male speaker. Our electroencephalography-based attention decoder classified every single trial using a template-matching method based on pre-defined patterns of cortical auditory responses elicited by either an “up” or “down” stream. The result of decoding was provided on the screen as online feedback. After four sessions of this neurofeedback training over 4 weeks, the subjects exhibited improved attentional modulation of evoked responses to the training stimuli as well as enhanced cortical responses to target speech and better performance during a post-training SiN task. Such training effects were not found in the Placebo Group that underwent similar attention training except that feedback was given only based on behavioral accuracy. These results indicate that the neurofeedback training may reinforce the strength of attentional modulation, which likely improves SiN understanding. Our finding suggests a potential rehabilitation strategy for SiN deficits.

Highlights

Understanding speech in noise (SiN) is crucial for effective communication
Neurofeedback Training of Selective Attention ability shows large individual differences even among young normal-hearing listeners (Choi et al, 2014), which may correlate with SiN performance (Strait and Kraus, 2011)
Our recent finding showed that the amplitude ratio of auditory-cortical responses to the target speech and noise during a SiN task correlated with behavioral SiN performance (Kim et al, 2021), indicating that attentional modulation on neural encoding of acoustic inputs in the auditory cortex (AC) would be a key neural mechanism for successful SiN understanding (Hillyard et al, 1973, 1998; Mesgarani and Chang, 2012; Carcea et al, 2017)

Summary

Introduction

Understanding speech in noise (SiN) is crucial for effective communication. It has been repeatedly reported that the ability to understand SiN differs dramatically, even across normal-hearing individuals (Kumar et al, 2007; Moore et al, 2013). Neurofeedback Training of Selective Attention ability (both behavioral performance and the attentional modulation of cortical responses) shows large individual differences even among young normal-hearing listeners (Choi et al, 2014), which may correlate with SiN performance (Strait and Kraus, 2011). A frequently reported problem of perceptual training is that the training effect does not generalize to other auditory stimuli not used for the training (Fiorentini and Berardi, 1981; Wright et al, 1997) This generalization problem leads us to consider training that directly improves a key strategy for the SiN understanding: a training that reinforces attentional modulation of auditory cortical responses. The goal of neurofeedback training is that if subjects learn how to adapt neural activity consciously, it may result in specific patterns of neural activity that reach the pre-defined threshold level, followed by a reward to the subjects (Vernon et al, 2003; Ros et al, 2010)

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Results