Frederick (Erick) Gallun, PhD
Research Investigator, VA RR&D National Center for Rehabilitative Auditory Research, VA Portland Health Care System, Portland, OR
Associate Professor, Department of Otolaryngology/Head & Neck Surgery & Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR
Central Auditory Dysfunction After Exposure to High-Intensity Blasts
Over the past decade, one of the core questions concerning both our laboratory and others has been the extent to which the central auditory system is vulnerable to damage from physical forces external to the body, specifically the effects of blast-induced pressure waves on the brain (for a full review and complete references, see Papesh and Gallun, 2015). Both animal and clinical research in shows that visible damage to the auditory cortex and brainstem can impair auditory function. What we wanted to know was the degree to which damage that could not be observed using medical imaging could also lead to auditory dysfunction. This question became of clinical relevance when the VA and military hospitals in the US began to see a large number of individuals with auditory complaints and yet presenting with normal audiograms, which is the clinical gold standard for peripheral auditory function. Read more.......
Dr. Bob Carlyon, Deputy Director
MRC Cognition & Brain Sciences Unit
Research update: Cochlear Implants
As it stands
Cochlear implants (CIs) have restored hearing to more than half a million deaf people worldwide. A typical CI processor extracts the slowly varying envelope in each frequency band; each envelope then amplitude-modulates a train of electrical pulses applied to one of an array of electrodes inserted in the cochlea, with higher-frequency bands applied to more basal electrodes. Variations on this theme include so-called n-of-m strategies, where in each short time window only a subset of electrodes, corresponding to the more energetic bands, are activated, and fairly recent strategies that convey information on the temporal fine structure of the lower-frequency channels. Read more.....
Starkey Hearing Research Centre
2110 Shattuck Ave #408 Berkeley CA 94704 USA
School of Medical Sciences
University of Sydney, NSW 2006 Australia
Hearables – a snap shot
Light and sound dominate our world. The consumer electronics industry has invested hugely in visual displays such as HDTV: 2D and 3D and now head mounted displays. Audio has enjoyed less investment but low energy Bluetooth and inexpensive DSP have enabled a wide range of reasonable quality, untethered audio devices that can travel with you or live in your ears. Another major area of development are the so-called smart technologies in the home, the car and wearable tech that can sense and even react to the environment. Activity and fitness trackers are the most visible of the wearable technologies, although they are yet to demonstrate lasting traction in the market. More interesting developments are at the intersections of these technologies such as AV displays for virtual and augmented reality and more recently, so-called hearables – headphones with benefits. Read more.....
Hidden Hearing Loss – the Problem and the Promise
Sharon G. Kujawa and M. Charles Liberman
Most adult hearing impairment is sensorineural in nature and arises from inner ear dysfunction. Dogma has long held that hair cells are the most vulnerable cochlear elements and that cochlear neural loss typically occurs only after, and because of, hair cell degeneration. Work from our lab, and others, over the last 10 years has shown that this is not true for key etiologies of acquired sensorineural hearing loss, including noise, aging, and ototoxic drugs (Kujawa and Liberman 2015). These insults can cause massive (>50%) loss of cochlear nerve peripheral synapses without any hair cell loss (see Figure). This extensive cochlear synaptopathy has remained a “hidden hearing loss”, because 1) diffuse neural degeneration does not significantly elevate cochlear pure-tone thresholds, or the behavioral audiogram, until it reaches 80%, 2) the synaptic connections between cochlear neurons and hair cells are hard to see in routine histological material, and 3) the cell bodies and central axons of cochlear neurons, survive for years to decades despite their loss of functional connection to the hair cells. Read more....