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 a vector, a matrix (first column), an object of class ts, Sample (left channel), or Wave (left channel).
f sampling frequency of wave (in Hz). Does not need to be specified if wave is an object of class ts, Sample, or Wave.
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 1.5.4 Index]