autoc {seewave}R Documentation

Short-term autocorrelation of a time wave

Description

This function returns the fundamental frequency of a harmonic time wave. This is achieved by computing a correlation of the signal with itself after a time delay.

Usage

autoc(wave, f, wl = 512, fmax, threshold = NULL, plot = TRUE,
xlab = "Time (s)", ylab = "Frequency (kHz)", ylim = c(0, f/2000),...)

Arguments

wave data describing a time wave or a Sample object generated loading a wav file with loadSample (package sound).
f sampling frequency of wave (in Hz). Does not need to be specified if wave is a Sample object.
wl length of the window for the analysis (even number of points, by default = 512).
fmax the maximum frequency to detect (in Hz).
threshold amplitude threshold for signal detection (in %).
plot logical, if TRUE plots the fundamental frequency against time (by default TRUE).
xlab title of the x-axis.
ylab title of the y-axis.
ylim the range of y values.
... other plot graphical parameters.

Details

Autocorrelation process can be time consuming.

Value

When plot is FALSE, autoc returns a two-column matrix, the first column corresponding to time in seconds (x-axis) and the second column corresponding to to fundamental frequency in kHz (y-axis).
NA corresponds to pause sections in wave (see threshold).

Author(s)

Jerome Sueur sueur@mnhn.fr and Thierry Aubin thierry.aubin@u-psud.fr

References

Hopp, S. L., Owren, M. J. and Evans, C. S. (Eds) 1998. Animal acoustic communication. Springer, Berlin, Heidelberg.

See Also

ceps

Examples

data(sheep)
# fundamental frequency of a sheep
autoc(sheep,f=8000,threshold=5,fmax=700)
# overlay on spectrogram
spectro(sheep,f=8000,ovlp=75,zp=16,scale=FALSE)
par(new=TRUE)
autoc(sheep,f=8000,wl=512,threshold=5,fmax=700,col="black",pch=20,
    xaxs="i",yaxs="i",ann=FALSE,yaxt="n")
legend(0.5,3.6,"Fundamental frequency",pch=20,col="black",bty=0,cex=0.7)

[Package seewave version 1.5.0 Index]