Objective: It was the aim of this study to explore the use of auditory steady-state response (ASSR) to multiple simultaneous stimuli for threshold estimation in young children. Method: The subjects consisted of 40 children, aged from 6 months to 5 years, with variant degrees of sensorineural hearing loss. Simultaneous tonepips (0.5, 1, 2 and 4 kHz) with an amplitude modulated at different rates from 77 to 103 Hz were presented to both ears by insert phones. All children were tested with ASSR and age-appropriate behavioral tests. Results: We found that (1) ASSR thresholds were usually higher than behavioral thresholds with a difference of 8–15 dB, (2) the behavioral thresholds were significantly correlated with ASSR thresholds (p = 0.000), and (3) there was a great difference between ASSR thresholds and behavioral thresholds found in a child with auditory neuropathy. Conclusion: Being objective, frequency specific and well correlated with behavioral thresholds, ASSR to multiple simultaneous stimuli was proven to be a good tool to predict behavioral hearing thresholds.

For 8 patients (53 stimulating electrodes) the correlation between tNRI threshold and M level was r=0.675 (p=0.000) and that between first NRI thresholds and M level was r=0.741 (p=0.000). On average the M-level value was 20 CU (Current Unit) lower than the first NRI threshold value and 12 CU higher than the tNRI threshold value. The M-level patterns across the electrode array overall were similar to the tNRI or first NRI threshold patterns. For 7 patients (112 stimulating electrodes) the correlation between EART and M levels was r=0.710 (p=0.000). On average the EART value was 14 CU higher than the M-level value.

The mean scores for the auditory skills improved significantly over time. The mean scores of three skills for each group at each interval were significantly different. The mean scores of the auditory skills were significantly superior for infants undergoing hearing aid trial and habilitation in comparison with those of infants without hearing aid trial and habilitation.

Objective: To investigate the effect of brief-tone stimulus duration on the amplitude of the brain stem auditory steady-state response (ASSR), both in single-and multiple-stimulus conditions. Design: In Experiment 1, the primary stimuli were Blackman-windowed 500-and 2000-Hz brief tones presented using repetition rates of 79 and 83 Hz, respectively. Stimuli had durations ranging from 0.5 to 12 msec. In the single-stimulus condition, these two stimuli were presented dichotically, whereas in the four-stimulus multiple-stimulus condition, instead of being presented alone, each stimulus was combined with three interfering stimuli, which were also Blackman-windowed brief tones spaced one octave apart, and presented at rates of 77 to 96 Hz. In Experiment 2, the effect of brief-tone duration and the effect of interfering stimuli were further studied by systematically removing interfering stimuli from the multiple stimuli, with the goal of determining which specific stimuli in the multiple stimuli were responsible for the interference. In both experiments, stimuli were presented at 75 ppe dB SPL. The subjects were normal-hearing adults, who relaxed or slept during the recording sessions.Results: Experiment 1: ASSR amplitudes increased as stimulus duration decreased in the single-stimulus condition, for both 500 and 2000 Hz. However, amplitudes did not significantly increase until stimuli were quite brief (2 msec for 2000 Hz; 6 msec for 500 Hz). In the four-stimulus multiple-stimulus condition, the pattern of amplitude increase with decreasing stimulus duration at 2000 Hz was similar to that in the single-stimulus condition, although amplitudes at all durations were reduced. However, for 500-Hz stimuli in the four-stimulus multiplestimulus condition, ASSR amplitudes showed no change as stimulus duration decreased. Experiment 2: for 2000-Hz stimuli, the 4000-Hz interfering stimuli resulted in the largest change in amplitude, the 1000-Hz interfering stimuli had a small effect, and the 500-Hz interfering stimuli had no effect. For 500-Hz stimuli, the 1000-Hz interfering stimuli had the greatest effect, the 2000-Hz interfering stimuli the next largest, and the 4000-Hz interfering stimuli a small effect. The interference effects for 500-Hz stimuli occurred only for brief (<6 msec) stimuli, with no effects of the interfering stimuli when the 500-Hz stimuli were 8 or 12 msec in duration. Conclusion:Although brief tones may result in larger-amplitude ASSRs, their duration must be quite brief (not more than three to four cycles) to show a significant amplitude increase. Moreover, when presented together with other stimuli in the multiple-stimulus technique, response interference reduces the amplitudes of ASSRs, and for 500 Hz removes the amplitude gain normally seen with decreasing duration. Brief-tone stimuli, therefore, may not be optimal for ASSR threshold estimation, especially because of the compromise in frequency specificity accompanying the use of very brief tones.

The results showed a significant improvement between first fitting and 6 months in all speech tests and in tone perception. The VAS scores showed a significant improvement over 6 months in sound quality and an immediate benefit in ease of listening.