The first thing

Choosing something to start with is an intimidating task. I think I’m going to make an allowance that I do not have to choose just one thing each day; rather, I can choose as many as I want. Hooray for more things worth learning!

That said, here is the thing I choose as “the best thing i learned today”:

I’m reading Brian C. J. Moore’s An Introduction to the Psychology of Hearing. In the section entitled “Basic Structure and Function of the Auditory System” (specifically, pp. 22-23 in the 5th edition), Moore discusses the functions of the middle ear (aka those little bones you learned about in elementary school – the hammer, the anvil, and the stirrup). The first function is to transmit sound effectively from the air in the ear canal to the fluid in the cochlea just past your eardrum (it’s an impedance-matcher), which is a really beautiful thing, if you look closely at it.

But the second function, he says, is to “reduce the transmission of bone-conducted sound to the cochlea.” If you’re chewing, the bones in your skull would naturally vibrate, including the bones in your middle ear. These little ear bones would transmit the waves to the cochlea, so these noises would “appear loud and have the effect of masking external sounds.” Bad news. However, the guy who studied all of this, Bárány, showed that the sounds are only transmitted to the cochlea “when there is differential movement between the ossicles and the skull.” Our middle ear is positioned exactly so that it minimizes this possible differential movement. So we can still hear when we’re eating! And, perhaps even more interesting, Moore suggests that birds and reptiles, who have a more simple middle ear that does transmit skull vibrations to the cochlea, “swallow their food whole rather than chewing it, whereas mammals chew their food.”

Wow. I mean, seriously. Is it for real? Only the speculation of science knows!

Close competitors:

February 21, 2007. academics, climbing, information visualization, sound. No Comments.

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