Lack of effect of contralateral speech discourse on auditory threshold response behavior.

Three pilot experiments were conducted with normal-hearing adults on the effects of contralateral speech discourse on monaural intensive threshold at 1 kc/s. Two voices simultaneously reading dissimilar passages were presented to the non-test ear. Pure tones and speech were led to insert receivers. Threshold assessment was by operant techniques with feedback for correct response. Stimulus presentation and response recording and retrieval were under computer control. Performance was analyzed by threshold central tendencies and variances, by slopes of performance-level curves, and by slopes of curves for response-decision latencies vs level. In Exper. I (N:5), Ss made threshold judgments while in the contralateral ear speech was presented at 30 db SL, in 2-sec samples with 2-25- sec silent intervals intervening. In Exper. II (N:3), the interrupted speech was at levels of -10, 10, 50, and 70 db; in addition, 4 blocks of thresholds were taken at 30 db SL to examine adaptation effects, if any. In Exper. III (N:3), speech was continuous at the levels of 10, 30, 50, and 70 db. None of the characteristics of the speech appeared to affect performance by any of the 3 indices at any level, for any S systematically. It was concluded that inter- and intra-subject variability may be the key to much of the conflicting results in the literature in the area of performance in noise.