noise

Name

noise --  A white noise generator with an IIR lowpass filter.

Description

A white noise generator with an IIR lowpass filter.

Syntax

ar noise xamp, kbeta

Initialization

ioffset -- the delay before the first impulse. If it is negative, the value is taken as the number of samples, otherwise it is in seconds. Default is zero.

Performance

xamp -- amplitude of final output

kbeta -- beta of the lowpass filter. Should be in the range of 0 to 1.

The filter equation is:

y_n = sqrt(1-beta^2) * x_n + beta Y_(n-1)
      

where x_n is white noise.

Examples

Here is an example of the noise opcode. It uses the files noise.orc and noise.sco.

Example 15-1. Example of the noise opcode.

/* noise.orc */
; Initialize the global variables.
sr = 44100
kr = 4410
ksmps = 10
nchnls = 1

; Instrument #1.
instr 1
  kamp = 30000

  ; Change the beta value linearly from 0 to 1.
  kbeta line 0, p3, 1

  a1 noise kamp, kbeta
  out a1
endin
/* noise.orc */
        
/* noise.sco */
; Play Instrument #1 for one second.
i 1 0 1
e
/* noise.sco */
        

Credits

Author: John ffitch
University of Bath, Codemist. Ltd.
Bath, UK
December 2000

Example written by Kevin Conder.

New in Csound version 4.10