Cognitive hearing science: the legacy of Stuart Gatehouse.

Stuart Gatehouse was one of the pioneers of cognitive hearing science. The ease of language understanding (ELU) model (Rönnberg) is one example of a cognitive hearing science model where the interplay between memory systems and signal processing is emphasized. The mismatch notion is central to ELU and concerns how phonological information derived from the signal, matches/mismatches phonological representations in lexical and semantic long-term memory (LTM). When signals match, processing is rapid, automatic and implicit, and lexical activation proceeds smoothly. Given a mismatch, lexical activation fails, and working or short-term memory (WM/STM) is assumed to be invoked to engage in explicit repair strategies to disambiguate what was said in the conversation. In a recent study, negative long-term consequences of mismatch were found by means of relating hearing loss to episodic LTM in a sample of old hearing-aid wearers. STM was intact (Rönnberg et al.). Beneficial short-term consequences of a binary masking noise reduction scheme on STM was obtained in 4-talker babble for individuals with high WM capacity, but not in stationary noise backgrounds (Ng et al.). This suggests that individuals high on WM capacity inhibit semantic auditory distraction in 4-talker babble while exploiting the phonological benefits in terms of speech quality provided by binary masking (Wang). Both long-term and short-term mismatch effects, apparent in data sets including behavioral as well as subjective (Rudner et al.) data, need to be taken into account in the design of future hearing instruments.