Can Semantic Context Information Mask Rollover In Hearing-Impaired Listeners?

At low presentation levels, an increase in level often improves speech audibility, which in turn usually leads to better speech intelligibility. However, this is not necessarily the case at high presentation levels, where increasing the level can lead to poorer intelligibility, that is, so-called rollover.
Rollover has been observed in listeners with both normal and abnormal audiometric thresholds. Furthermore, rollover has been observed at above-conversational speech levels in quiet and at conversational speech levels in background noise. In a previous study, we found that semantic context information can mask rollover in normal-hearing listeners, presumably reflecting the use of top-down processing.
Here, we investigated the influence of semantic context information on rollover presence in hearing-impaired listeners. Speech intelligibility in noise was measured with context-free and context-rich sentences at two speech presentation levels, that is, at 10 dB above the individual most comfortable speech level and 85 dB SPL. The noise levels were individually set for each speech material and participant. To ensure audibility, a wearable hearing-aid simulator providing individual linear amplification was used.
Consistent with our hypothesis, initial results indicate that rollover will be found with the context-free sentences but not the context-rich sentences.