Auditory brainstem encoding of speech-in-noise predicts word identification, narrative comprehension, and subjective...

The auditory brainstem plays a crucial role in speech-in-noise listening, refining numerous acoustic features such as pitch and spatial location under continual descending influence from cortex. However, the difficulty of characterizing brainstem activity during continuous speech listening has obscured its functional role in ecologically valid contexts-not only the effects of selective attention on neural responses, but also their impact on comprehension and listening effort. Here, we evaluated the role of the brainstem on speech-in-noise perception and other listening behaviors using a continuous, speech-based stimulus with embedded chirps (Cheech) that rapidly and effectively evoked auditory brainstem responses (ABRs) while 25 participants listened to short story narratives (n=15 females, 10 males). The Cheech-modified stories were presented alone or in the presence of another spatially separated talker, and neural responses were measured throughout by EEG. Both word-level detection performance and narrative-level comprehension were evaluated, as well as subjective reports of listening effort. ABR wave V was modulated by the presence of a competing talker. Additionally, wave V peak amplitudes were associated with identification speed of the target words embedded within the stories, while faster latencies related to better target word identification accuracy, comprehension question accuracy, and lower subjective listening effort. Collectively, our results provide evidence for the influence of brainstem encoding processes on individual speech-listening behaviors, including the ability to selectively attend to and comprehend target speech in the presence of a competing talker.Significance statement This study highlights the crucial role of the brainstem in speech-in-noise perception and higher-level language abilities like comprehension and subjective listening effort. Through the use of a novel speech stimulus blended with embedded chirps (Cheech) to evoke brainstem responses while listening to short story narratives, we show how subcortical processes relate to successful speech-listening performance across multiple behavioral metrics. These findings advance our understanding of how the brainstem supports speech perception, comprehension, and perceived effort in challenging listening environments.