SS01: NOISE REDUCTION IN HEARINGS AIDS AND ITS EVALUATION

SELF-RATED EFFORT, COGNITION AND AIDED SPEECH RECOGNITION IN NOISE

Rudner M (1)(2), Lunner T (1)(3)(4), Behrens T (4), Thorén ES (3)(4), Rönnberg J (1)(2).

(1) The Swedish Institute for Disability Research, Linköping University, Sweden;(2) Department of Behavioural Sciences and Learning, Linköping University, Sweden; (3) Department of Medical and Experimental Medicine, Linköping University, Sweden; (4) Oticon A/S, Research Centre Eriksholm, Snekkersten, Denmark.

Speech recognition in noise is an effortful process requiring explicit cognitive processing. It may be influenced by level and type of noise and by the signal processing algorithms employed when hearing is aided. These complex relationships may be understood in terms of the working memory model for Ease of Language Understanding (ELU, Rönnberg et al., 2008). This model predicts that under challenging listening conditions, explicit cognitive processing demands will be high and that persons with good explicit cognitive capacity will be better listeners.

Two previous studies (Behrens et al., 2004; Rudner et al., 2008) indicated a link between cognitive capacity and self-rated effort on a visual analogue scale in connection with aided speech recognition in noise under some conditions when the listening situation was particularly challenging. Although the general pattern of results was similar in the two studies it was not clear how the experimental manipulations influenced the relationship between cognitive capacity, performance and perceived effort. In order to obtain more stable data and clarify the pattern of results, an overall reanalysis of the two studies was performed.

Preliminary results show significant negative correlations between self-rated effort and cognitive capacity at low, but not high, SNR in both steady-state and modulated noise, suggesting that the perceived effort involved in listening with a hearing aid in noisy situations is less for individuals with good cognitive resources. Further, perceived effort correlated positively with speech recognition performance at both low and high SNR when noise was modulated but only at low SNR when noise was steady state. These findings suggest that in challenging listening situations, persons with high cognitive capacity may perceive that they have cognitive spare capacity available to cope with even more challenging listening situations, whereas persons with lower cognitive capacity may perceive that their capacity is taxed to the utmost. These findings support the ELU model.