Both attended and unattended contexts influence speech perception to the same degree.

Often, listening to a talker also involves ignoring the speech of other talkers (‘cocktail party’ phenomenon). Although cognitively demanding, we are generally quite successful at ignoring competing speech streams in multi-talker situations. However, the present study demonstrates that acoustic context effects are immune to such attentional modulation. This study focused on duration-based context effects, presenting ambiguous target sounds after slow vs. fast contexts. Dutch listeners categorized target sounds with a reduced word-initial syllable (e.g., ambiguous between gegaan “gone” vs. gaan “to go”). In Control Experiments 1-2, participants were observed to miss the reduced syllable when the target sound was preceded by a slow context sentence, reflecting the expected duration-based context effect. In dichotic Experiments 3-5 , two different context talkers were presented to the participants’ two ears. The speech rate of both attended and unattended talkers was found to equally influence target categorization, regardless of whether the attended context was in the same or different voice than the target, and even when participants could watch the attended talker speak. These results demonstrate that acoustic context effects are robust against attentional modulation, suggesting that these effects largely operate at a level in the auditory processing hierarchy that precedes attentional stream segregation