Continued search for better prediction of aided speech understanding in multi-talker environments.

To better understand issues of hearing-aid benefit during natural listening, this study examined the added demand placed by the goal of understanding speech over the more typically studied goal of simply recognizing speech sounds. The study compared hearing-aid benefit in two conditions, and examined factors that might account for the observed benefits. In the phonetic condition, listeners needed only identify the correct sound to make a correct response. In the semantic condition, listeners had to understand what they had heard to respond correctly, because the answer did not include any keywords from the spoken speech. Hearing aids provided significant benefit for listeners in the phonetic condition. In the semantic condition on the other hand, there were large inter-individual differences, with many listeners not experiencing any benefit of aiding. Neither a set of cognitive and linguistic tests, nor age, could explain this variability. Furthermore, analysis of psychometric functions showed that enhancement of the target speech fidelity through improvement of signal-to-noise ratio had a larger impact on listeners' performance in the phonetic condition than in the semantic condition. These results demonstrate the importance of incorporating naturalistic elements in the simulation of multi-talker listening for assessing the benefits of intervention in communication success.