Scientists have charted the acoustic world of harbor porpoises, gathering a vast array of knowledge about their Umwelt, or how the porpoises use their sensory organs to communicate, locate food and process sound. "By combining knowledge gained from tagged wild harbor porpoises with the results of experiments performed on trained animals, we are improving our knowledge of these elusive small whales, so that we can better understand their acoustic Umwelt, and in this way refine our ways of protecting them and the environment in which they live," Magnus Wahlberg, Meike Linnenschmidt, Peter Madsen, Danuta Wisniewska and Lee Miller write in American Scientist.
Following are a selection of interesting news items from our field. This section will be updated on a continuous basis so check back often in between issues, to see what is new.
Pearlfish in French Polynesia use oyster shells to amplify sounds over long distances, according to research published in the Journal of Experimental Biology. The fish swim into black-lip pearl oysters and the shells increase the volume of the vibrations created by the fish's swimbladders. "Amplification probably improves the efficiency of communication by increasing the propagation distance of the sounds," said University of Liege researcher Loic Kever.
Researchers at the University of Melbourne have published a study that shows children with a history of otitis media (middle ear disease) during early childhood go on to have binaural speech perception deficits, which may persist for years after they have the disease. The researchers noted that these language perception problems can make it difficult to isolate auditory information from background noise, which can make it difficult to succeed academically, so the authors recommend that children with a known history of otitis media have their spatial hearing capacity assessed when they enter school.
AG Bell Releases New Professional Practice Protocol Alexander Graham Bell Association for the Deaf and Hard of Hearing
The Alexander Graham Bell Association for the Deaf and Hard of Hearing has released a new professional practice protocol for audiologists with recommendations for assessments, hearing aid and cochlear implant evaluations and follow-ups. According to the association, the protocol “is intended to support programs for early detection and management of hearing loss in infants and children. It also is a guide to appropriate and ongoing audiology services recommended for children pursuing a listening and spoken language outcome.”
The term misophonia, coined in 2000 and meaning “hatred of sound”, is being used to describe a rare and newly-recognized disorder characterized by an extreme sensitivity to sound. “Trigger sounds” such as eating noises, pen clicking and typing, can cause people with misophonia to become irritated, stressed and angry.
The cause of the condition is still unknown, but experts seem to believe that the context of the noises, rather than the sounds themselves, is the issue: audiologist Natan Bauman thinks misophonia is a “learned conditioned response,” a negative association with certain sounds that triggers an impulsive reaction. Josef Rauschecker, director of the Laboratory for Integrative Neuroscience and Cognition at Georgetown University believes that misophonia could be classified as a subtype of tinnitus. There is currently no cure though a few treatment options do exist.
Rachel Miller spent nearly five years trying to figure out what was causing a set of bizarre symptoms — including dizziness, “weird” eye movements and sensitivity to sounds – before neurologist David Zee, a vertigo expert at Johns Hopkins, told her that she had superior canal dehiscence syndrome (SCDS). This recently-identified disorder results from thinning or a hole in the inner ear’s temporal bone and is believed to be present at birth, though it can take a head injury to cause symptoms to develop. Miller had an operation in 2012 that has helped her to feel like herself again.
The National Institute for Health Research’s Nottingham Hearing Biomedical Research Unit in the U.K. is coordinating a national survey that will look into the prevention, diagnosis and management of mild to moderate hearing loss. The survey will collect perspectives from patients who have been affected by hearing loss as well as their friends and family members, in hopes of gaining “valuable insights into which are the most important unanswered questions for research.”
A way to prevent noise-induced hearing loss has been found in a mouse using a simple chemical compound that is a precursor to vitamin B3. This discovery has important implications not only for preventing hearing loss, but also potentially for treating some aging-related conditions that are linked to the same protein.
In this article, author Kerry Flynn interviewed Dr. Brian Fligor, an audiologist who specializes in headphone use, about how to listen to music without damaging your ears. Fligor offers several helpful tips, such as suggesting that headphone users follow the “80/90 rule” (listening at about 80% of the maximum volume for no more than 90 minutes) and seeing an audiologist to get customized headphones.
Scott Novich and David Eagleman, neuroscientists at Baylor College of Medicine in Houston, have developed a VEST (versatile extra-sensory transducer) that converts spoken language into unique patterns of vibration. They have raised money for their research through a Kickstarter campaign and hope that the sensory substitution devices will eventually be available for less than $2,000 per unit.