Delay
Description
The delay effect combines
the unprocessed signal with a delayed copy of itself. The amplitude of the delayed copy is scaled by a factor g. The length
of the delay is measured in seconds. Since the sampling rate varies, often
times it is beneficial to measure the delay in samples. Given a delay time
period d (sec), and a sampling rate sr (Hz), the number of samples in the delay
can be calculated in the following formula:
Number of samples in the delay = f * s
In using delay, the tempo of
the song can be factored in to align the delay time with the beat. Used
creatively with precision, the delay can land on or subdivide the beat. Given
the tempo in beats per minute bpm, the duration between beats can be calculated
by the following formula:
Duration between beats = 60/bpm
Graphical Depiction of Delay Effect
Signal Formula
|
y(n) = output signal |
|
x(n) = input
signal |
|
y(n) = x(n) + g * x(n – M) |
|
M
= delay time measured in samples |
|
M
= sr * d |
|
sr
= sampling rate (Hz) |
|
d
= delay time (sec) |
|
g = gain |
Source Code
(.csd files can be viewed with Notepad or any text
editor)
Example Audio Clips
|
Original Unprocessed
Signal |
|
|
1 second delay |
|
|
500 ms delay |
|
|
250 ms delay |
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.