Cognitive Hearing Science

Abstract

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.

The Ease of Language Understanding (ELU) model: theoretical, empirical, and clinical advances

“…For example, Tun et al (2009) have shown poorer delayed recall for audible auditory stimuli in participants with impaired compared to normal hearing when encoding took place under divided attention conditions. Rönnberg et al (2011a,b) also demonstrated that short-term memory performance under divided attention encoding conditions correlated with degree of hearing impairment (cf. Humes et al, 2006).…”

“…Attentional resources may contribute to speech understanding, especially in effortful or divided attention tasks (Tun et al, 2009; Rönnberg et al, 2011a,b). For example, Tun et al (2009) have shown poorer delayed recall for audible auditory stimuli in participants with impaired compared to normal hearing when encoding took place under divided attention conditions.…”

“…By including hearing aid users ( n = 160) from the longitudinal Betula study of cognitive aging (Nilsson et al, 1997), we made a conservative test of the hypothesis that hearing impairment is negatively related to episodic LTM deficits. The basis of the prediction from the ELU model (Rönnberg et al, 2011a,b) is that mismatches will remain despite the use of a hearing aid, and hence fewer items will be encoded and retrieved from episodic LTM. Therefore, we assume a disuse effect on episodic LTM, leading to a less efficient episodic memory system.…”

“…These predictions have recently been confirmed by structural equation modeling. Episodic LTM decline is related to long-term hearing impairment, despite the use of existing hearing aid technology (Rönnberg et al, 2011a,b). One note of caution though is that exact measures of every-day hearing aid use were not available.…”

“…Visual acuity alone, or in combination with auditory acuity, did not contribute to any acceptable structural equation model; it only made the prediction of episodic LTM decline worse by standard goodness-of-fit criteria (see also Lindenberger and Ghisletta, 2009). And finally, even when the episodic LTM tasks were of non-auditory nature (i.e., motor encoding of lists of imperatives and subsequent free recall of these actions, Nilsson et al, 1997) the association with hearing loss persisted (Rönnberg et al, 2011a,b). …”