Jeff Weihing, University of Louisville
Frank Musiek, Editor HHTM Pathways, University of Arizona
A new feature of HHTM Pathways that is beginning this month is the revisiting of one of the truly historic journals in audiology and hearing science —The Journal of Auditory Research (JAR). The venerable J. Donald Harris was the originator and editor of this esteemed scientific communication. The journal ran from 1960 to 1986 and introduced many of the foundational studies in the fields of audiology and auditory science. Because of J.D. Harris’ guidance, JAR was viewed by many as having innovative and thought-provoking articles and commentary. JAR also had a wide-based appeal achieving an excellent balance between clinical and basic science.
The goal of the Journal remained the same throughout its history. The publication covered such fields as: otology, audiology, psychoacoustics, musicology, speech and communications, neurophysiology of audition, instrumentation for hearing research, and auditory aspects of human engineering.
In many ways, the purpose of JAR was a predecessor to Hearing Health and Technology Matters (HHTM) in that it was intended to provide information used by all who had an interest in the area of hearing. JAR provided scientific study, so this is a distinction between JAR and HHTM at this time. Interestingly, Harris’ Editorial Policy Board, although it changed over the years, was composed of four distinguished individuals (in addition to himself as Editor) throughout the life span of the Journal. They were Norton Canfield, M.D., Karl D. Kryter, Ph.D., Alvin Liberman, Ph.D., and E. Glen Wever, Ph.D.
The JAR reflected Don Harris’s perspectives on basic and clinical investigation. He had an open mind and a sharp eye for innovation. He could detect a diamond in the rough in regard to research ideas and would do his best to support young clinicians and researchers.
“Simple reaction time: Evidence for two auditory pathways to the brain” by V. T. Wynn
The first JAR that we will review is “Simple reaction time: Evidence for two auditory pathways to the brain” by V. T. Wynn from the University of Exeter, Exeter, England. This report appeared in JAR in 1977.
Wynn shows that two performance distributions emerge when auditory stimuli are used in reaction time time tasks: one which is essentially normally distributed and occurs when the stimuli are presented at higher intensity levels, and a second which is bimodal and occurs when the stimuli are presented at lower levels.
Why would a bimodal distribution be observed? The article lacks some key information, such as details on how responses were measured, presentation mode, and importantly – hearing acuity. However, despite these short comings, the extremely large N makes this finding compelling. Could it be that the bimodal distribution shown in figure 1 reflects variations in hearing sensitivity? This is a possibility, but it is probably not quite that simple. Since this is an auditory-motor response, responses to the stimulus could reflect a contralateral route across the corpus callosum for some measurements and for others a more ipsilateral route. Further, since the motor system is a totally crossed system, an ipsilateral motor response would require impulses to travel across the corpus callosum while a contralateral response would not. The approximate 30-msec difference in the two peaks of the bimodal distribution is in keeping with transfer times across the corpus callosum.
Given the lack of information on hearing sensitivity and ear stimulated, this idea must be very tentative. However, the corpus callosum link is consistent with the author’s notion of different pathways and/or extra synapses. A wide variety of scenarios could be entertained as to how and why the corpus callosum process would be initiated for some of these measurements and not others. To delineate these possibilites is beyond the scope of this discussion. Suffice it to say it seems a possibility and I would direct those interested for further information to read about the Poffenberger technique [Poffenberger, A. Archives of Psychology, 23,1, 1912]. Another possibilty is that there could be fast and slower pathways to the brain. Could it be that the the now known non-classic and classic auditory pathways have different synaptic and conduction velocities and therefore yeild a bimodal distribution? [Mohanni et al. Hearing Journal: 64, 6, 2011]
Another interesting finding in this study is that reaction times to visual stimuli show only a single normally distributed histogram, in contrast with the two distribution outcome for auditory stimuli. Why doesn’t the visual system show the bimodal distribution? Since the visual system is also a completely crossed system, there may be less physiological indecision relative to the auditory system, which has both ipsilateral and contralateral input. That is, the visual system would require less callosal involvement than the auditory system.
Dr. Jeffrey Weihing received his Master’s and Doctoral degrees in Audiology from the University of Connecticut, where he specialized in electrophysiology, vestibular assessment, and the diagnosis and treatment of (central) auditory processing disorder. He currently provides clinical services and is an instructor in the Au.D. program at the University of Louisville. His research interests include generation of more sensitive measures of hearing in noise ability, identifying neurologic bases for auditory processing disorder in children, establishing efficacious treatments for auditory processing disorders, and using electrophysiological measures to predict outcomes in hearing aid fittings.