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.

Speech-in-noise (SiN) understanding involves multiple cortical processes including feature extraction, grouping, and selective attention. Among those processes, we aimed to investigate the causal relationship between auditory selective attention and SiN performance. Selective attention enhances the strength of cortical neural responses to attended sounds while suppresses the neural responses to ignored sounds, which forms an evidence of sensory gain control theory. We hypothesized that the cortical response-guided neurofeedback could strengthen the sensory gain control, which in turn will improve selective attention performance and may result in better SiN understanding. With a single-blinded, between-subjects design including a placebo group, subjects were asked to attend to one of two simultaneous but asynchronous streams. For the participants assigned to the experimental group, a visual feedback was provided after each trial to demonstrate whether their attention was correctly decoded using their single-trial EEG response. The experimental group participants with four weeks of this neurofeedback training exhibited amplified cortical evoked responses to target speech as well as improved SiN understanding, while the placebo group participants did not show consistent improvement. To our best knowledge, this is the first report of selective-attention training enhancing SiN performance.

AbstractSelective attention enhances cortical responses to attended sensory inputs while suppressing others, which can be an effective strategy for speech-in-noise (SiN) understanding. Here, we introduce a training paradigm designed to reinforce attentional modulation of auditory evoked responses. Subjects attended one of two speech streams while our EEG-based attention decoder provided online feedback. After four weeks of this neurofeedback training, subjects exhibited enhanced cortical response to target speech and improved performance during a SiN task. Such training effects were not found in the Placebo group that underwent attention training without neurofeedback. These results suggest an effective rehabilitation for SiN deficits.