[sdiy] ye olde sawtooth

[Antti Huovilainen]

On Sun, 18 Mar 2001, Matti wrote:

> What immediatel springs to mind is......the ear's inherent non-linearity.
> As the air particles push in on the ear, they've got those bones on the
> inside to contend with, so the very peaks on the negative end of a
> waveform will be rounded, less peaked, and won't deviate as far from zero
> as the positive peaks will, be the time it reaches the brain.

And I thought I'd never get to use anything I learnt at university... ;)

Our acoustics professor said that ear essentially performs a half-wave
rectification to each critical band. So the structure is like this:

bandpass filter -> halfwave rectifier -> lots of weird neuro stuff

The bandpass filter is more like a lowpass filter with resonance (slow
rise and fast dropoff after the peak). The halfwave rectifier explains why
absolute phase DOES matter. You can hear this on bassdrums (real ones, not
synth) where reversing the phase does have an effect (at least sometimes).

Antti

"If you don't eat yer meat, you can't have any pudding!
 How can you have any pudding if you don't eat yer meat!?"
   - Roger Waters