Clinical application of the synchronized sentence set (S³)

Nearly 15 years ago, the US Army (ARL-HRED) developed the Synchronized Sentence Set (S³) to assess the benefits of spatialized speech presentation for military personnel working in multi-talker environments. The S³ consists of 2034 sentences (10 syllables each) constructed from 104 token phrases and recorded by four male talkers. When presented together, sentences are temporally synchronized in a manner allowing key words in individual sentences to begin and end at the same time. The S³ companion software enables the user to simultaneously present one target (T) message and up to three competing (C) messages during a test condition. The user can independently route the T- and C-messages through one or more transducers (e.g., earphones or loudspeakers) to create a variety of divided and selective attention tasks. The purpose of this study was to determine whether the S ³ and companion software could be used to assess speech perception in multi-talker noise in a clinical setting. Sentences from the S³ were presented via (1) standard supra-aural earphones (diotically or dichotically), (2) four loudspeakers, and (3) a 3-D audio earphone system that simulated the positions of the four loudspeakers. Participants (N=26) listened to T-messages in the presence of 0, 1, 2 and 3 C-messages. The listeners' task was to record key words from the T-messages on a custom response sheet (640 trials/participant). Results indicated significant decreases in performance as the number of T-messages increased, for all listening modes. In conditions involving two or three C-messages, however, participants performed significantly better when T-messages were routed through loudspeakers or the 3-D audio system. Findings suggest that the S³ and companion software may offer clinicians and researchers with a reliable and flexible tool for assessing listener performance in multi-talker noise.