A matrixed speech-in-noise test to discriminate favorable listening conditions by means of intelligibility and response time results

Purpose: The primary aim of this study was to develop and examine the potentials of a new speech-in-noise test in discriminating the favorable listening conditions targeted in the acoustical design of communication spaces. The test is based on the recognition and recall of disyllabic words sequences. A secondary aim was to compare the test with current speech-in-noise tests, assessing its benefits and limitations. Methods: Young adults (19-40 years), self-reporting normal hearing, were presented with the newly developed words sequence test WST (16 participants, Experiment 1), with a consonant confusion test and with a sentence recognition tests (Experiment 2, 36 participants randomly assigned to the two tests). Participants performing the WST were presented with words sequences of different length (from two up to six words). Two listening conditions were selected: (a) no noise, no reverberation, (b) reverberant, steady-state noise (Speech Transmission Index: 0.47). The tests were presented in a closed-set format; data on the number of words correctly recognized (speech intelligibility, IS) and the response times RT were collected (onset RT, single words RT). Results: It was found that a sequence composed by four disyllabic words ensured both the full recognition score in quiet conditions and a significant decrease in IS results when noise and reverberation degraded the speech signal. Response times increased with the worsening of the listening conditions and the number of words of the sequence. The greatest onset RT variation was found when using a sequence of four words. In the comparison with current speech-in-noise tests it was found that the WST maximized the IS difference between the selected listening conditions, as well as the RT increase. Conclusions: Overall, the results suggest that the new speech-in-noise test has good potentials in discriminating conditions with near-ceiling accuracy. As compared with current speech-in-noise tests, it appears that the WST with a four words sequence allows for a finer mapping of the acoustical design target conditions of public spaces through accuracy and onset RT data.