Synthesis Theory I: Assignment 1
Choose one of the following exercises. Do more than one exercise for
Write a short piece or compositional study (less than 5 minutes) which
is generated solely by additive synthesis. You may use any program to
generate the piece. Write a 1-2 page analysis/description of your piece.
Plot the loudness at which sound is barely audible for a range of frequencies
from 20 to 20,000 Hz. Use at least 20 frequencies: 40, 100, 200, 500, 1000,
2000, 3000, 4000, 5000, 6000, 8000, 10000, 12000, 15000, 16000, 17000, 18000,
19000, 20000. Compare your plot to the Fletcher-Munsen equal-loudness curves
around 0-10 dBSPL/phons.
Plot the loudness in decibels: 20 * log10(amplitude)
Experiment with sound masking (which is the fundamental principle used in
MPEG audio compression). Choose a frequency (e.g. 1000 Hz) and
set it to a moderately loud volume. Play a second sinewave (say 1100
Hz) at the same loudness and at the same time as the first sinewave.
Can you hear both sinewaves? (I hope so.) Reduce the volume of the second
sinewave until you cannot hear it sounding with the first sinewave.
Plot the loudness at which the second sinewave "disappears". Plot
the masking loudness of about 20 frequencies for the same first sinewave.
Compare to this sample plot.
Synthesize timbres for various instruments from frequency data collected
by Carl Seashore in the book Psychology of Music (Call number:
1967 on reserve in the library starting Tuesday afternoon for 350.867). Have several
people listen to your instrument syntheses and identify the instruments
(don't tell them what it is before they hear it, of course). Which
timbres were easy or difficult to identify? Write a 1-2 page analysis
of the results.