seewave (version 1.1)

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, fmin, threshold = FALSE, plot = TRUE,
xlab = "Time (s)", ylab = "Frequency (kHz)", ylim = c(0, f/2000), ...)

Arguments

wave

data describing a time wave.

f

sampling frequency of wave.

wl

length of the window for the analysis (even number of points).

fmin

the minimum 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

• If plot is FALSE, autoc returns a vector of numeric data describing the fundamental frequency in kHz. NA corresponds to pause sections in the signal (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

data(sheep)
# fundamental frequency of a sheep
autoc(sheep,f=8000,wl=512,t=5,fmin=700)
# overlay on spectrogram
spectro(sheep,f=8000,wl=512,ovlp=75,zp=16,scale=FALSE)
par(new=TRUE)
autoc(sheep,f=8000,wl=512,t=5,fmin=700,type="p",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)