The Contralateral Acoustic Reflex Threshold Using Speech Stimuli: A Comparative Study

The acoustic reflex (AR) is a subject that has been highly studied in the field of audiology. In fact, the physiology of the AR has been debated about since the 16th century. Historically and clinically the AR has been elicited with pure tone stimuli. In the 1970’s and 1980’s different eliciting stimuli were experimented with, such as: broadband noise (BBN), highband noise (HBN), lowband noise (LBN) and speech stimuli. The amplitude modulation of speech has made it difficult to record the acoustic reflex threshold (ART) due to the artifact that it creates on the measuring machine. When ecological validity, or the ability of the findings of the research to be applied to real-life setting, is taken into account, speech signals are the most valid of all types of stimuli that have been used to elicit the AR. In this study, three concatenated speech stimuli were created from the NU-6 word list 1-A. The words for the NU-6 word list 1-A were concatenated together to create one long speech stimuli, this was done to eliminate the impact of the artifact created by the amplitude modulation that is caused by the pauses in speech. The focus of this study was to compare the contralateral ART using the speech stimuli as the eliciting stimuli for the ART with a pure tone stimulus and different noise stimuli. Together, the findings presented here provide evidence supporting the use of the speech stimuli when measuring the ART clinically. The findings also suggest potential application and further research opportunities for noise induced hearing loss caused by self-vocalizations and a potential correlation for pure tone versus speech ART when testing individuals with central auditory processing disorders.