Relationship Between Auditory and Visual Noise Acceptance in Normal-Hearing Listeners.

BACKGROUND: Research has shown that hearing aid acceptance is closely related to how well an individual tolerates background noise, regardless of improved speech understanding in background noise. The acceptable noise level (ANL) test was developed to quantify background noise acceptance. The ANL test measures a listener's willingness to listen to speech in noise rather than their ability to understand speech in noise, and is clinically valuable as a predictor of hearing aid success. PURPOSE: Noise acceptance is thought to be mediated by central regions of the nervous system, but the underlying mechanism of noise acceptance is not well understood. Higher order central efferent mechanisms may be weaker and/or central afferent mechanisms are more active in listeners with large versus small ANLs. Noise acceptance, therefore, may not be limited to the auditory modality but observable across modalities. We designed a visual-ANL test, as a parallel of the auditory-ANL test, to examine the relations between auditory and visual noise acceptance. RESEARCH DESIGN: A correlational design. STUDY SAMPLE: Thirty-seven adults between the ages of 21 and 30 years with normal hearing participated in this study. DATA COLLECTION AND ANALYSIS: All participants completed the standard auditory-ANL task, the visual-ANL task developed for this study, reception thresholds for sentences using the hearing in noise test, and visual sentence recognition in noise using the text reception threshold test. Correlational analyses were performed to evaluate the relations between and among the ANL and perception tasks. RESULTS: Auditory- and Visual-ANLs were correlated; those who accepted more auditory noise were also those who accepted more visual noise. Auditory and visual perceptual measures were also correlated, demonstrating that both measures reflect common processes underlying the ability to recognize speech in noise. Finally, as expected, noise acceptance levels were unrelated to perception in noise across modalities. CONCLUSIONS: The results of this study support our hypothesis that noise acceptance may not be unique to the auditory modality, specifically, that the common variance shared between the two ANL tasks, may reflect a shared general perceptual or cognitive mechanism that is not specific to the auditory or visual domains. These findings also support that noise acceptance and speech recognition reflect different aspects of auditory and visual perception. Future work will relate these ANL measures with central tasks of inhibition and include hearing-impaired individuals to explore the mechanisms underlying noise acceptance.

Mental tasking and rotary Chair-Induced vestibular nystagmus utilizing Video-Oculography.

Objective: To investigate whether the use of mental tasking, when compared to no mental task, affects measurement of nystagmus response with regard to gain, phase & symmetry, and artefact when utilising video-oculography (VOG) as the measurement technique in rotary chair testing (RCT).Design: A within-subject repeated-measures design was utilised.Study samples: Seventeen (17) healthy adults were evaluated (age 22-25 years). Each participant underwent slow harmonic acceleration (SHA) testing for 0.01, 0.02, 0.04, 0.08, and 0.16 Hz using RCT at two separate counterbalanced visits. At one visit mental tasking was utilised while the other visit did not utilise mental tasking. The following outcomes were measured for each visit: gain, phase, symmetry, and artefact.Results: No significant difference between the tasking conditions with regard to gain, phase, symmetry, or artefact. Significant frequency affects were noted, as expected, for gain, phase, and artefact. Analysis of individual subject data did, however, describe significant effects of tasking with regard to gain, phase, symmetry, and artefact.Conclusion: These results suggest that the use of mental tasking during RCT using VOG had no significant group effect on SHA gain, phase, symmetry, and artefact. However, individual subject effects were observed indicating variability in the effects of mental tasking during RCT.

Mental Tasking and Caloric-Induced Vestibular Nystagmus Utilizing Videonystagmography.

PURPOSE: The purpose of this study was to quantify the effects of mental tasking on measures of the caloric vestibulo-ocular reflex utilizing videonystagmography as the measurement technique. METHOD: A within-subjects repeated-measures design was utilized. Sixteen healthy adults were evaluated (13 women, 3 men; ages 19-31 years). Each participant underwent bithermal caloric irrigation at 2 separate counterbalanced visits. At 1 visit mental tasking was utilized, whereas the other visit did not utilize mental tasking. The following outcomes were measured for each visit: peak slow-phase velocity (SPV), response duration, peak SPV latency, and eye blink artifact. RESULTS: No significant difference was seen for tasking versus no tasking with peak SPV, peak latency, or response duration. A significant difference was seen for the amount of eye blink artifact, with significantly more eye blinks present for the tasking condition. CONCLUSIONS: Results could indicate mental tasking does not affect the important measure of SPV. Moreover, increased eye blink artifact with tasking could obscure the clinician's ability to read the nystagmograph. However, this investigation is limited to the healthy young adult population, and more studies should be performed to corroborate the presented evidence.