Given that the scientists were basically just guessing, anyone have any better guesses than the monkey thing?
What the heck, I’ll start: Instinctive response to prevent us from grinding our teeth together, maybe? Tooth grinding doesn’t make the high-pitched noise of nails on a chalkboard, but the scientists found that’s not the offensive part of the sound, anyway. And although I haven’t done any waveform comparisons, I’d say tooth grinding does sound a bit like their second most offensive sound, styrofoam cups scraping together (to my ear, anyway).
Of course this is a very WAG, but WAGs are probably all we’ll be able to come up with in this case.
Of course, my tooth grinding speculation is contingent on it being possible for someone to grind their teeth dull to the point where they’re at a survival disadvantage BEFORE reaching the point where they start hurting, which would probably be a sufficient deterrent all by itself. I have no idea if this is the case. Any other guesses (or comments on this one) are welcome.
Being a live sound engineer for many years, its become clear to me that hi-mid frequencies are probably the most irritating, and generally need to be softened in an eq. Where this particularly comes into play is that really annoying guitar sound from the 60’s, a la the Byrds “Turn Turn Turn”. Guitars set on the bridge pickup (the one closest to the bottom) will tend to accentuate these frequencies, and thus need to be softened or the audience will shudder. A lot of times, when faced with the ability to use a graphic EQ, most amateurs will find the “smily face” shape, where the lows are up and the extreme highs are up and the mids are down generates the most pleasant listening experience. Down with mids!
Its also interesting to note that mids are where most of the sounds complexity is. It could be that we are most sensitive to mids because that is where we get most of our distinguishing information from. As we get older, high frequencies become harder for us to hear, and unless there is a lot of power behind them, low frequencies are difficult to hear as well. A good example of this is on the phone. It doesnt take a lot of sound energy coming off your phone to make you hold it away from your ear, thats all high mids.
Remember the announcer from MAS*H ?
btw I realize the extreme high frequencies are technically the most complex, I was speaking of timbre and where we get our ability to distinguish sounds from each other.
The fact is, not all people find finger nails on a chalkboard irritating. I have a friend who actually enjoys the sound, though I can’t imagine why. The simple fact is, all sounds can be either irritating or soothing, and the reasoning varies from persont to person.