Investigating the relationship between spectro-temporal modulation detection, aided speech perception, and directional noise reduction preference in hearing-impaired listeners

Resumé

In analogy to the restoration of reduced audibility via hearing-aid amplification, supra-threshold speech processing deficits may be partially compensated for by using state-of-the-art directional noise reduction (NR) techniques. However, while amplification is usually prescribed based on classical audiometry, a clinical test that represents supra-threshold speech processing and is thus useful for prescribing NR settings is yet to be established. The present study explored the potential of a suitably adapted spectro-temporal modulation detection (STMD) test for this purpose by means of laboratory-based tests and field tests with 30 hearing-impaired participants. In particular, it was investigated whether STMD performance (i) predicts aided speech intelligibility measured in a spatial multi-talker set up with different degrees of NR and (ii) predicts preference for moderate vs. aggressive NR. STMD thresholds were strongly correlated with (i) speech scores measured without NR, (ii) speech intelligibility benefit induced by aggressive NR, and (iii) the individual participants’ NR preference. The latter relationship was mediated by performance in a reverse digit span task, which measures working memory capacity. Overall, the results suggest that a clinical test that assesses STMD sensitivity may be useful for prescribing NR settings in hearing-aid fitting.