Inner Ear Biology
retrospectacle | February 5, 2007Many of my SciBlings have been doing posts on "basic concepts" in their fields of expertise. As I am studying hair cell regeneration as a therapy for hearing impairment, I thought I might do a 'basic concepts post' on what hearing is, how humans hear, and why we lose it sometimes.
The most reductionist answer is the ability to perceive sound in an environment. However, to humans, hearing is much more complex than that, as we use sound to communicate to others or to appreciate music. Humans, among many other species, perceive sound waves through holes in our heads (ears). However what we…
retrospectacle | January 3, 2007Hey Wall Street Journal! I say boooooo to you and this worthless article on the "impending hearing health crisis." The title of the article ("Resolve to Turn Your Ipod Down") itself is rather silly, now that Ipods come with volume limits under the range of the levels that cause hearing loss. Plus, its not like earbuds or portable music is anything new: we've had the Walkman for years, and before that kids would just hold boom-boxes by their ears. Concerts have been around for ages, yet no one says "Resolve To Stop Attending Concerts." Boo.
(Continued below the fold.............)
The article…
retrospectacle | November 7, 2006Check out this really interesting study over at Cognitive Daily, which explores the differences in acoustic and visual processing times. The authors of the study used a very elegant, simple protocol to demonstrate how accurate people are at reporting synchrony and "dis-synchrony."
One side note was that raw auditory processing times are faster than visual processing times. This may have to do with the levels and depth of processing that visual stimuli undergoes, and the amount of information (color, depth, size, position, movement, distance, etc) that must be integrated into a coherent "…
retrospectacle | September 13, 2006Mark Chu-Caroll related a story in the comments to this post, about how his son benefited greatly from having tubes put in his ears after recurring ear infections became a serious issue.
For children who get frequent ear infections, tympanostomy tubes can be a very effective, and low-impact treatment. (An explanation of ear infections, and how they occur, is here.) A small tube is inserted into the eardrum, which allows the built-up fluid that has accumulated behind the eardrum to drain out. It also allows air to once again permeate the middle ear, and helps prevent further infections.…
retrospectacle | September 12, 2006A little more on the topic of ear infections, from Forbes:
A new study found that almost two-thirds of children given a prescription for antibiotics -- just in case -- didn't need to have the prescription filled to get better.
"Our study evaluated a 'wait-and-see' prescription for ear infections in children," said the study's lead author, Dr. David Spiro, who was at Yale University School of Medicine at the time of the study. "Compared to children who were given antibiotics, children in the wait-and-see group had the same outcomes."
Spiro, who now heads Pediatric Emergency Medicine at…
retrospectacle | September 12, 2006Yeah, I have an ear infection (otitis media). So, why not take this opportunity to describe what an ear infection is, why it hurts, and what you can do about it.
Otitis media literally means "middle ear inflammation," but it really refers to the build-up of infected fluid in the spaces in the middle ear, behind the ear drum, which are usually filled with air. This causes pressure to accumulate in this space, which translates to pain and the feeling of "ear fullness." The pressure can distort the ear drum slightly, which also causes pain and a reduced ability to hear in that ear. Children get…
retrospectacle | August 10, 2006Once when i was in a taxi, the driver was attempting to make conversation and asked what I did. I usually try to avoid the subject with some people, because when i say "I study the inner ear" a lot of people feel the need to unload their medical problems regarding earwax upon me. Only half-way through their offering a sample (ugh) can I correct them. Anyway, this cabbie did just that--asking me this and that about earwax. After I said I had no idea, he seemed rather like "Well then what DO you know!" Its even worse when i try to reply that I study hair cells in the ears---invariably this…
retrospectacle | August 9, 2006In addition to the below post on gene therapy, keep a watch out for a review paper on the topic (by yours truly) that was just accepted into Hearing Research.
Deafness and hearing impairment are serious medical concerns in America, with nearly 30 million Americans affected to some degree. This is such a widespread problem in our society due to the combined effects of loud noises, aging, and heredity. Hearing loss happens when cochlear hair cells are lost (for a primer on the cochlea and hair cells, go here). Mammals, including humans, are unable to re-grow hair cells although birds and a few…
retrospectacle | July 10, 2006Researchers at the University of Antwerp have identified three genes, involved in potassium ion channels in the inner ear, which are essential for normal hearing protection. Defects in these genes have been shown to significantly decrease the cochlea's ability to protect itself from noise-related injuries. (More below the fold....)
The team pinpointed the genes during a study of over 1000 Swedish men who had all been exposed to loud noises while working in factories. 80% of these participants had been subjected to this noise for at least 20 years. The teams tested the mens' hearing thresholds…
retrospectacle | July 3, 2006The head of the Kresge Hearing Research Center here at UM (link to the left) is Dr. Jochen Schacht. His team recently discovered that taking the antioxidents Vitamin E and aspirin significantly reduced hearing damage after noise trauma (ie, a rock concert.) Info below the fold..........
From the NIDCD's site:
Exposure to loud sounds or noise can lead to noise-induced hearing loss (NIHL) by damaging and/or destroying the inner ear's sensory hair cells. Scientists believed that NIHL damaged the hair cells by the pure force of the loud sound vibrations. In that case, the only NIHL prevention…
retrospectacle | June 29, 2006The NIDCD reported yesterday the discovery of a protein called protocadherin-15 (PC15)(which is associated with a form of genetic deafness called Usher Syndrome) as the likely player in the initial transduction of sound. As I have discussed here, the cochlea's sensory cells are called hair cells which project "hairs" into fluid spaces that vibrate when sound waves pass through. The "hairs" (called stereocilia) of each hair cell are connected by very important proteins called tip links. These links must be present for the transduction of sound to occur; when stereocilia are deflected, the tip…
retrospectacle | June 16, 2006Hat tip to Abel Pharmboy for this fascinating story! A recent US government study has found that:
a) Black adults hear better than white adults
b) Women hear better than men
c) Average hearing thresholds are the same in the US as they were 35 years ago (despite the much-maligned iPod and Walkman!)
(More under the fold....)
The large-sample-size study (5,000 people) was conducted by the National Institute for Occupational Safety and Health, and mirrors the results of smaller, previous studies. This study examined hearing tests collected from 1999 to 2004 as part of a comprehensive federal…
retrospectacle | June 14, 2006So, both myself and Cognitive Daily have highlighted the recent news story that high school students have hit upon a ringtone that teachers can't hear. CognitiveDaily instituted a poll over in one of their posts with a supposed 17kHz sound clip (hey, who would have doubted the New York Times?), but it was pointed out that the sound was, in fact NOT 17kHz, but 14hHz. The difference is this: as we age, high-frequency hearing is the first to go, and 17kHz is quite a bit "higher" than 14kHz, which means that older people can still hear it. Loss of hearing is called presbycusis (better known as…
retrospectacle | June 12, 2006Kudos to some clever students who have discovered an interesting little trick about human hearing and manipulated it to their advantage. According to this Yahoo blurb and NY Times story, kids are downloading an extremely high-frequency ringtone which often exceeds the hearing range of adult teachers. The reason for this is that, as people age, hair cells are first lost in the high-frequency region of the cochlea. Essentially, as we age we are less able to perceive sounds in high frequencies; this begins in early middle age. Kids can hear the ring just fine, as they still possess hair cells in…
retrospectacle | June 10, 2006If you read the 'About' page, or anything about me, you probably noticed that I work on hair cell regeneration in the cochlea. But, perhaps, some readers are not familiar with the machinations of the inner ear. So, I'll make a quick post with some relavent info to help in understanding future hearing and ear-related postings.
The sense of "hearing" refers to the detection of sound waves in our environment. Humans are able to distinguish a lof of information out of these waves: direction (due to fact we have two ears!), loudness, pitch, timbre, and frequency. Waves are "collected" by the…