<p>Attending a lecture requires remaining focused for extended periods, which is particularly difficult in noisy environments or when lecture content is less engaging. Yet little is known about how these external (noise) and internal (interest) factors affect learners’ neurophysiology. We measured brain activity (electroencephalogram; EEG) and physiological responses (skin conductance) during video-based learning, and assessed how neurophysiological responses were modulated by the presence of realistic background noise and by varying levels of interest throughout the lecture. Interest-level showed pronounced neurophysiological effects, with low-interest segments associated with reduced neural speech tracking, elevated alpha-power, reduced beta-power, and increased arousal, a pattern consistent with lower engagement and increased listening effort. Interestingly, background noise had comparatively limited effects on neurophysiological responses. These dissociated impacts of internal and external factors on speech processing during learning, emphasize the profound impact of content-engagement on neurophysiological measures associated with learner’s attention, beyond the sensory burden of noise.</p>