Commodore Plus 4 - Page 118

CREATING
A NOISE
SOUND
EFFECT
Using a value of 3 when selecting a voice in the SOUND command
specifies noise. This is used to create sound effects with noise rather
than tone. The following program uses voice 3 to create the sounds of
a windstorm.
sets VOLume level
selects RaNDom
number from 1 to 10
10
VOL 2
20R = INT(RND(0)
30FORX = 1TOR
40 SOUND 3, 600 + 30*X, 10
50 NEXT X
60FORX-RTO1STEP -1
70SOUND,3,600-30*X, 10
80 NEXT X
90 T = INT{RND(0)-100)-30
100 SOUND 3, 600, T
110 GOTO 20
Lines 30 and 60 set up loops for the note value (frequency) of the
sound, one increasing and one decreasing, based on the random
number from line 20. It is important to have variation in pitch, since
windstorms have different forces of gusts of wind. Lines 40 and 70 are
the SOUND commands that create the noise. Lines 90 and 100 set up
a random delay to recreate the uneven nature of a windstorm with time
lapses between howls The program selects a RaNDom number that
is used for the duration of another SOUND command. This SOUND
command stays at the same pitch and provides a consistent back
ground noise that serves as a counterpoint to the gusts of wind.
Creating sound effects using noise is extremely challenging, trying
to capture the right elements of the sound you wanl exactly. To create
good sound effects, you have to be willing to experiment.
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