Effect of a contralateral masking stimulus on auditory response performance.

HTLs at 1 kc/s were obtained from the L ear of 5 normal-hearing adults by Bekesy, Up-Down, and Ascending procedures, as a function of a contralateral narrow-band noise mask centered at 1 kc/s, at 70 db SL. Insert receivers were used in each ear. Bekesy tracing width was also examined, and in the Up-Down and Ascending procedures also response-level performance and the latency of the response decision. Masked and masking stimuli were presented simultaneously, both in either continuous or pulsed form. HTLs differed in quiet as a function of the temporal characteristics of the test tone, and in noise, as a function of the temporal presentation of the masked and masking stimuli. All Ss yielded higher threshold shift with contralateral (i.e., central) masking under the pulsed/pulsed than under the continuous/continuous presentation in the Bekesy procedure. The pulsed masking noise slightly decreased Bekesy tracing widths, while the continuous masking signal slightly increased them. Neither the temporal characteristics of the test tone, nor the presence/absence of the contralateral masking signal led to any systematic change in either the performance-level curves or the latency of the response decision. However, both the performance-level curves and the latency of the response decision were differentially affected by the experimental procedures. The Bekesy may be the procedure of choice for investigating central masking.

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.

Intra- and intermodal discrimination transfer in auditory and visual discrimination training.

The purpose of this study was to investigate intra- and intermodal discrimination generalization-transfer in auditory and visual "same-different" discrimination training. Two subjects were trained in an auditory discrimination task, two in a visual discrimination task and two received no training. Discrimination performance was assessed on 12 visual and 12 auditory stimulus conditions at pre- and posttraining intervals for all subjects. The 4 subjects receiving training also were probed for performance at three intervals during the training. Results indicate that subjects trained to a task in one sensory modality demonstrate improved discrimination performance on untrained stimulus discrimination within (intra-) and between (inter-) sensory modalities, whereas, untrained subjects tended to show less improved performance.

Conditioning the middle ear reflex at sensation levels below reflex threshold: air jet and electrical stimulation.

An ABAB functional analysis, conditioning and generalization, design was used in 3 experiments (2 were formal studies and 1 was empirical in nature) to investigate the conditionability of the middle ear reflex. The conditioned stimuli were subreflex threshold pure tones of various frequencies and intensities. The unconditioned stimulus (UCS) was an auricular air jet to the contralateral ear in the first experiment and cutaneous electrical stimulation to the ipsolateral, probe ear in the last 2 experiments. Reflexes were monitored by an otoadmittance meter, storage oscilloscope, and strip chart recorder. In the first experiment (air jet UCS), no subjects met the conditioning criterion within the maximum presentation of 400 paired trials, despite pilot evidence which indicated conditioning was feasible. In the second experiment (electrical stimulation UCS), 2 subjects met conditioning criterion; however, only one subject reconditioned and demonstrated partial generalization to other conditioned stimuli. In the third experiment (electrical stimulation UCS), one of 3 subjects who had previously been unconditionable with the air jet UCS met conditioning and reconditioning criterion and demonstrated partial generalization. Results indicate that the middle ear reflex can be conditioned to be elicited by subreflex threshold pure tones, however, results are limited.

Response behavior around auditory threshold.

Normal adults, hearing-impaired preschool children, and normal-hearing mentally retarded children were assessed across repeated measures for auditory thresholds at 250 and 1000 Hz. Each subject's total performance across repeated measures was plotted by group by frequency relative to the last point of 100% correct response and interpolated thresholds. The results indicate that the steepness of the percentage of correct response performance curves and the variability of response performance above and below interpolated threshold were related to differences between the adult and child groups (mental age) and not between types of hearing populations (hearing sensitivity). The relationship between these results and experience with the signal is speculated.

Hearing assessment with young children.

This study evaluates the efficacy and reliability of auditory stimulus-response control training and assessment procedures with young children (nine to 25 months). The problems encountered in training stimulus-response control are discussed. Results indicate that reliable interest data can be obtained from young children using stimulus-response control procedures.