listening:  Turenas, John Chowning (1972) ca. 9 min. quadraphonic

Reading: Chapter 5 (due Nov-1).

Assignment: homework #5 Record and analyze two mystery tones, both sustained, listening through
your tube. One should be extremely quiet, the other extremely loud. You'll need to be very aware of signal level at
all stages including the mic preamp. Turn in an html page like before, with a short recording and sonogram of
each. We'll play name that tone, so don't give it away.

Topics:

sampling (cont'd):

• dynamic range
• decibel conversion for amplitude ratios, 20 * logbase10 (amplitude1 / amplitude2)
• doubling amplitude = 6dB gain
• signal intensity = square of signal amplitude
• decibel conversion for power ratios, 10 * logbase10 (intensity1 / intensity2)
• doubling power = 3db gain

     Wave length to period (sec.) (depends on speed of sound) [meters / meters per sec.]
     Wave period to frequency (Hz.) [1 / sec.]
     Hz->radians per sample (depends on srate) [freq. * 2pi  /  samples per sec.]
     Tempered scale (semitones, midi)  to frequency ratio [2  ^  (degree / 12) ]

(review) --

all programming tokens are from these categories:
 

Scheme	Scheme extensions	Snd	CLM	220 conventions
procedures define lambda let let* round ceiling *, +, /, - expt set! do random log10 1+ constants #t, #f	procedures   lambda* [for #&optional syntax]	procedures   map-chan make-vct vct-set! vct-fill! new-sound hz->radians procedures that return constants or pointers   srate samples selected-sound selected-channel	procedures   make-delay delay tap procedure that returns a constant mus-srate	procedures   click zeroes noise variables   x0, y0 xz, yz

transform to the frequency domain involves

• FFT window
• size -- frequency resolution vs. time resolution
• type -- peak sharpness, side lobes
• dB magnitude
• 2D spectrum
• 3D
• sonogram
• spectogram waterfall
• peak identification