Tremolo
Description
Tremolo is a periodic
variation in the volume of a sound. It can be implemented by multiplying the
input signal by a low frequency oscillator. The variable parameters of the
oscillator are amplitude range and frequency. The minimum and maximum values of
the oscillator are each between 0 and 1. A minimum of 0 and maximum of 1 will
cause the gain to fluctuate between full volume and silence. The rate of the
fluctuation is determined by the frequency of the oscillator.
Graphic Depiction
Effect Formula
|
y[n] = A * x[n] |
|
x[n] = input
signal |
|
y[n] = output
signal |
|
A = [maxValue -
minValue] * [1/2 sin (ft) + 1/2] + minValue |
|
maxValue = maximum
oscillator value |
|
minValue = minimum
oscillator value |
|
f = oscillator
frequency (Hz) |
|
t = time (sec) |
Source Code
(.csd files can be viewed with Notepad or any text
editor)
Example Audio Clips
|
Original Unprocessed
Signal |
|
|
Tremolo with a constant
frequency of 6 Hz, a minimum value of 0, and a maximum value of 1 |
|
|
Tremolo with a linearly
increasing frequency ranging from 0 Hz to 40 Hz, a minimum value of 0, and a
maximum value of 1 |
References
Lehman, Scott
(1996). Effects Explained. Harmony Central. Retrieved 6/04 from
http://www.harmony-central.com/Effects/effects-explained.html
Mikelson, Hans
(2000). Modeling a multieffects processor in Csound. In Boulanger,
Richard (2000), The Csound book (pp 575-594). Cambridge, MA: MIT Press.
Schindler,
Allan. (1998). Eastman Csound tutorial.
Eastman School of Music. Retrieved 6/04 from
http://www.esm.rochester.edu/onlinedocs/allan.cs/
Vercoe, Barry.
(1992). The public Csound reference manual, version 4.16. MIT
Press. Retrieved 6/04 from http://www.lakewoodsound.com/csound/hypertext/manual.htm
Zolzer, Udo.
(2002). Digital audio effects. West Sussex, England: Baffins Lane.