Residual Noise Using Intelligent Hearing and Vivosonic Integrity ABR Systems

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Residual Noise Using Intelligent Hearing and Vivosonic Integrity ABR Systems

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Julie Thein, B.S., Joseph Vasey, B.S., Linda Norrix, Ph.D. and David S. Velenovsky, Ph.D.

Department of Speech, Language, and Hearing Sciences, The University of Arizona


This experiment was designed to test the effectiveness and efficiency of the IHS (using artifact rejection) and VIVO (using Kalman filtering, the Amplitrode, and Bluetooth) ABR systems in reducing residual noise (RN). Adults were tested while they were asked to maintain a quiet, relaxed state and also during periods of induced motor movement. Measures from each system were simultaneously recorded to eliminate any differences in noise levels due to sequential recording from each system individually, thus any noise present would be at equal levels for both systems. A residual noise level of 0.025μV was our criterion for effectiveness. Averaging time to examine efficiency ranged from 1-3 minutes for the Relaxed Conditions and 1.5-6 minutes for the Active Conditions. The maximum averaging times were chosen based on what we concluded would be the longest reasonable time that a clinician would spend averaging a single run in a clinical setting.

abr montage


Relaxed State

•There was no significant difference in RN between the IHS and the VIVO…

•however, for 3 minutes of averaging, the VIVO was more effective (11/16 participants met the RN criterion) than the IHS (5/16 met the RN criterion).

•Some activity level existed in the Relaxed State Conditions. Note an average of 699 rejects out of 6780 total sweeps using the IHS with 3 minutes of averaging.

•Kalman weighted averaging (every sweep counts but high amplitude sweeps are weighted less than low amplitude sweeps), Amplitrode and Bluetooth may be of benefit in relaxed states with periodic bouts of activity.

Active State

•VIVO (Kalman, Amplitrode, Bluetooth) was more effective in reducing RN in all active conditions than was IHS (artifact rejection). VIVO reached the average RN criterion by ≈ 6 minutes of averaging whereas the IHS did not. While a longer averaging time might reduce RN further, this is not practical in a clinical setting.

•RN levels for VIVO as a function of averaging time did not vary by noise type (intermittent vs. constant), whereas the duration and amplitude of motor activity had a large impact on RN level as a function of averaging time for the IHS (Figure 8).

•Increasing the artifact rejection (AR) level from 10 μV to 20 μV in the 6 minute intermittent “mouth” condition reduced RN level slightly (3374 more sweeps in the average); however the average RN did not meet the 0.025 μV criterion. The duration and amplitude of the motor noise is likely to influence whether a RN criterion can be met in a timely manner using a higher AR level.


abr residual noise

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