oct-11

hw2

1) make a microphone,
2) cut a tube,
3) measure its length (metric) and
4) record an impulse sounding in the tube to get the speed of sound and it's periodicity
5) using the script below, create a simulation with IIR echoes that has the same pitch and approximately the same decay
6) create a web page located at the pathname ~/Library/Web/220a/hw2.html

include:

tube length

a graph of the tube's response to an impulse (use Snd:file:print to get a .eps image, then convert to .jpg with Gimp:file:saveas)

your calculation of speed of sound in air and the tube's fundamental peridicity

the procedure call for your simulation, e.g., (map-chan (echo .01 .5)) ; delay = .01 secs attenuation = 0.5

a graph of the simulation output sound

(define echo ; IIR version, aka feed-back or recursive delay

(lambda* (secs #&optional (att 1.0))

(let ((del (make-delay (round (* secs (srate)))))

(yz 0.0) ; use yd, i.e., send output to delay

(y0 0.0))

(lambda (x0)

(set! yz (tap del)) ; where it comes back from delayline

(set! y0 (+ x0 (* att yz)))

(delay del y0) ; feed into delayline

y0)

)))

(map-chan (echo .01 .5)) ; smaller attenuation gets shorter echo series, by damping it faster