Cool piece by Rod Smith in the Seattle Weekly this week on sub-bass frequencies and the military. This subject always makes me think of Throbbing Gristle. When I was working for Simon R. as the research assistant for his post-punk book, I interviewed the legendary Monte Cazazza on a trip to California. Monte worked a lot with Throbbing Gristle in their early days, and was the one who coined the term "industrial music" when he made an accidental crack about "industrial music for industrial people." I asked him to talk about TG's experiments with infrasound (very low-frequency sounds) and with ultrasound (very high frequency sounds)--most notably the time that TG tried to force a band of transients off their property in Hackney with the power of sonics. Monte was tantalizingly vague, but offered a few pearls of wisdom. (Pick up the book for more details.)
Rod discusses a lot of the bodily correlates of infrasound--that very low frequencies might cause unfortunate gastrointestinal effects and worse. He doesn't really have the room to get into the neurological correlates of infrasound. What's happening on the level of the brain when you're exposed to very low frequencies?
There was a cool scientific study published in the journal Physiological Behavior in the year 1978, or on the TG timeline, between Second Annual Report and 20 Jazz Funk Greats. Researchers exposed rats to infrasound, and found that the levels of a neurotransmitter called norepinephrine had been altered. That's not too surprising, because your body releases norepinephrine when it's under stress. But the study gave early credence to the idea that your brain chemistry could possibly be altered--temporarily, at least--in response to very low frequencies. Norepinephrine's interesting because it's not only involved in stress, but it's also involved in creating new memories. (Another study two years later gave rats tranquilizers, and then exposed them to infrasound.)
Animal behavior is one area where infrasound gets studied a lot. In 1990, researchers in Frankfurt found that there were actually special infrasound-sensitive neurons in pigeons that respond to frequencies below 20 hertz, in a region called the cochlear ganglion. And one explanation why a tiger's roar is so scary for other animals (including humans) to hear is that part of the sound of the roar lies in the netherworld of infrasound, below 20 hertz; parts of a tiger's growl can be 18 hertz and lower. This was only substantiated pretty recently, in a 2000 study by a group of bioacousticians who measured the sounds that 24 tigers made over a period of time.
Another interesting thing: there's a gender difference in how people respond to these sounds. Women are apparently more attuned to these sounds than men are. There could be evolutionary reasons why this might be so.