Date of Award

Spring 2011

Document Type

Dissertation

Degree Name

Doctor of Audiology (AuD)

Department

Department of Communication Sciences and Disorders

Advisor(s)

Brenda M. Ryals

Lincoln C. Gray

Dan C. Halling

Abstract

Auditory brainstem responses (ABRs) are important for acquiring frequency specific information for determination of the degree and type of hearing loss for infants and difficult-to-test populations when behavioral audiometry cannot be carried out. This study investigated the effects of Kalman weighted filtering and in-situ pre-amplification employed by the Vivosonic Integrity V500 ABR system on threshold accuracy and efficiency in an environment of high physiologic noise in comparison to a conventional ABR system which employs a standard artifact rejection paradigm. Auditory brainstem responses were collected using the Vivosonic ABR system and a conventional ABR system both in quiet and in noise using tonal stimuli at 500 and 4000 Hz (eight total conditions). ABRs were administered to twenty adult participants with normal hearing acuity (behavioral thresholds better than 20dB HL). Physiologic noise was created by having the participant chew gum to emulate the movement of an infant sucking on a bottle or pacifier. Results indicated that there was a statistically significant main effect for equipment when examining all data (both quiet and noisy) with the exception of “No Responses” at 4000 Hz indicating that the Vivosonic measured significantly lower, more accurate, ABR thresholds than the conventional system regardless of activity level. There was no significant main effect for equipment noted when examining all data (both quiet and noisy) with the exception of “No Responses” at 500 Hz indicating that each system measured similar thresholds at this frequency. When dividing the data into subsets by frequency, no statistically significant differences were found for threshold accuracy measurements between the Vivosonic and the conventional systems in quiet or in noise at either 500 or 4000 Hz. At 4000 Hz, the Vivosonic equipment was found to be significantly more efficient at acquiring threshold than the conventional ABR system, but again no difference between systems was noted at 500 Hz. Findings suggest that neither system was particularly accurate or efficient at 500 Hz as it appears that physiologic noise is problematic at this frequency with either traditional artifact rejection of with Kalman weighted filtering and in-situ pre-amplification. Further exploration into the effects of Kalman weighted filtering and in-situ pre-amplification are warranted based on the findings of this study. Trends indicated in this study suggest that Kalman weighted filtering and in-situ pre-amplification may lead to more accurate and more efficient ABR acquisition without the need for sedation, at least for higher frequencies.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.