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... ):

Time domain analisys of a tube



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 ):

Time Domain model of modeled Impulse

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