MUS220a
HomeWork2
1- Calculation of the speed of sound using an impulse through a tube of certain
lenght.
Tube lenght = 53.5 cm
Periodicity of the impulse: 3msecs
That is, it takes 3 msecs for the impulse to travel the full lenght of the
tube forward, encounter a mass of air that makes it bounce and return to
the same start point where our pickup device is.
Results: 0.535 m x 2 (twice the distance) = 1.07 m / 0.003 secs
= 356.6 m/s
2- Simulate an actual sound impulse (the same used before) using a single
sample (machine created) and a IIR filter.
Our model looks like this (and
sounds...
):
Our IIR filter has only two parameters: attenuation and time interval for
the repetitions.
> (map-chan (echo .003 .5))
We set the interval to 3 msecs and consider a constant
rate of about half the amplitude every repetition to obtain
the following (and
sounds
):
which roughly preserves the same outline of amplitudes (or so it looks...understandably
it does not sound like it, though). By diminishing attenuation and tuning more precise the frequency peaks it sounds better; use (map-chan (echo .00318 .813)
Rodrigo Segnini