Neuroscience Seminar : The cognitive demands imposed by noisy, masked or otherwise degraded speech

When speech is heard in the presence of background sound, or when hearing is impaired, the sensory information at the ear is often too ambiguous to support speech recognition by itself. In such circumstances, knowledge-guided processes that help to interpret and repair the degraded signal are required. First, I will present recent work that illustrates the importance of different sources of knowledge (such as meaningful context, and familiarity with a talker’s voice) and how these may act to facilitate speech understanding. Then I will present work that elucidates a brain system involved in at least a subset of repair processes, and demonstrate how activity in this system appears to be gated by attention. Finally, I will conclude by describing how listening effort – a concept that has recently become more popular since it may relate to important individual differences in speech perception that are unexplained by intelligibility-performance measures - can be understood in relation to different cognitive demands imposed during perception of degraded speech.