Message no. 576[Branch from no. 568] Posted by Thomas Culhane (1311520071) on
Nice post Michelle. I have to tell you all, living in
For months now my wife and I have found it impossible to get a good night's sleep and it has affected our physical and mental health greatly. The delivery trucks wake us up between and two a.m. with their roaring engines as they stop by the construction sites to dump huge loads of sand and bricks (they can't deliver in the morning because the traffic is so bad in
I started reflecting on why certain sounds have a particularly deleterious effect on us, and here is the theory I have come up with:
For millions of years we mammals with forward facing eyes, a lack of night vision, and ears on the sides of their heads had to deal with two very disturbing environmental incidents that affected our survival.
The first was the presence of a predator that we could not see. We used the position of our ears and our sensitive hearing to try and predict when danger was around us, but eventually the predators found a way to outsmart us. Through eons of experimentation predators discovered that rather than trying to silently sneak up on us, if they made very low pitched growling noises they could instead cause us to freeze in panic and confusion.
Why would this be so? It turns out that we can only locate sounds whose wavelength is shorter than the distance between our two ears. If the wavelength (or its multiples) is longer than that distance we can't discern its direction. Thus, if a predator makes a sound with such a long wavelength, we don't know which way the predator is approaching from and hence we don't know which way to flee. This leads to confusion and panic. Either we stay still, or we run in random directions -- often right into the predator pursuing us.
As it turns out, low frequency sounds (low pitched sounds) have the longest wavelengths. The higher frequency (higher pitched) sounds of crackling leaves or broken twigs are shorter in wavelength than the distance between our ears, and hence we can tell where these sounds come from. So if a predator tries to be quiet and sneak up on us, and makes a mistake by stepping on a twig she will be less successful than one who reveals her presence by emitting a deep low growl. Thus, predators tend to growl.
Similarly, any member of our family or tribe or species that gets caught by a predator needs help to escape and will emit a high pitched sound -- a scream -- whose wavelength is shorter than the distance between our ears. By screaming our troubled loved one gives us a good idea of his location so we can rescue them. But screams also tell us that there is tremendous danger in that location and get our adrenalin and fear responses going.
What happens, after all those millions of years of tuning our ears for these two primal threats, when technologies are invented that mimic growls and screams on a daily basis?
I submit to you that diesel engines and other rumbling motor sounds are so similar to predator growls in wavelength and acoustic characteristics that they make us internally tremble with fear all the time. But our neocortex tells us "there is nothing to worry about, it is just traffic noise" and this causes cognitive dissonance. The result is a gradual wearing away of our ability to adapt and cope -- the new brain ("neo-cortex") is trying valiantly to fight messages from our old brain ("paleo-cortex") and this exhausts us.
I also submit that the squeal of car brakes and car horns and car alarms approximate the high pitched screams of trapped loved ones or other conspecifics. This makes us snap to attention (isn't that the attention of the car alarms you described!) so that we search out where the source of danger is coming from.
The result: A constant feeling in our bones that something isn't right, that we are under threat, and that we must either run away (but where?) or run to help (but whom?).
I predict that when we replace all of our diesel engines and other growling combustion engines (truck and bus engines in particular) with Franklin Fuel Cell engines (which can still use diesel fuel, but silently and cleanly! See "Neutralizing Diesel's Idle Threat in Wired Magazine -- http://www.wired.com/news/technology/0,1282,55646,00.html and
It is my strong (but empirically untested) belief that much of the stress we face in our lives is due to the unfortunate resemblance between traffic noises and the results of millions of years of having to avoid predation. Hopefully we can implement the technological changes I have described in our lifetimes, and find out if I am right!