autoc: 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).

sampling frequency of wave (in Hz). Does not need to be specified if wave is an object of class ts, Sample, or Wave

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.

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).

Details

Autocorrelation process can be time consuming.

References

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

Examples

Run this code

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)

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