Individual listening success explained by synergistic interaction of two distinct neural filters

Successful speech comprehension requires the listener to differentiate relevant from irrelevant sounds. Recent neurophysiological studies have typically addressed one of two candidate neural filter solutions for this problem: the selective neural tracking of speech in auditory cortex via the modulation of phase-locked cortical responses, or the suppression of irrelevant inputs via alpha power modulations in parieto-occipital cortex. However, empirical evidence on their relationship and direct relevance to behavior is scarce. Here, a large, age-varying sample (N=76, 39textendash70 years) underwent a challenging dichotic listening task. Irrespective of listeners’ age, measures of behavioral performance, neural speech tracking, and alpha power lateralization all increased in response to spatial-attention cues. Under most challenging conditions, individual listening success was predicted best by the synergistic interaction of these two distinct neural filter strategies. Trial-by-trial fluctuations of lateralized alpha power and ignored-speech tracking did not co-vary, which demonstrates two neurobiologically distinct filter mechanisms.