posted on Sep, 26 2004 @ 08:14 PM
I think I actually found it the other day on a bus, not a laughing matter.
Catching a ride to uni, the bus that i caught was an older bus and wasn't running very smoothly. As far as I previously knew (before reading this
forum) the brown noise was around 7.5Hz. So, while on the bus and noticing my growing need to find a toilet, i tried to work out what freq we were
The poles and seats on the bus were vibrating slow enough that i could see their movements, so i presumed it to be less than 20Hz, given film frame
rates are 20-25Hz and we cant notice the flicker. Then I thought about engine speed in RPM. A large diesel engine like that in a bus should idle
smoothly at around 700-800 RPM, which gives a cycle of rate of 11.5-13.5Hz. Ordinarily on a bus this shouldn't affect us, because there should't be
significant vibrations passed through the bus, but because the engine was running rough it caused an affect.
It was worst while stopped at lights while idling, not while driving as the RPM were higher. It was much worse on the one occasion where we stopped at
the lights and the engine slowly stalled. it took a couple of seconds for it to happen through which the RPM dropped and the vibration of the bus
slowed, making me feel like something was going to slip. fortunately, this was the last set of light before uni and i could get the hell outta
So if you wanna make a brown noise machine, try to get an engine that can idle down to speeds of ~450 RPM and make it a little rough. That should do
the trick. However, it sound like you should watch out for paralysis or bone disintegration at some of these frequencies.