dfreq: Dominant frequency of a time wave

Description

This function gives the dominant frequency (i. e. the frequency of highest amplitude) of a time wave.

Usage

dfreq(wave, f, channel = 1, wl = 512, wn = "hanning", ovlp = 0, fftw=  FALSE, at =
NULL, tlim = NULL, threshold = NULL, bandpass = NULL, clip = NULL,
plot = TRUE, xlab = "Times (s)", ylab = "Frequency (kHz)",
ylim = c(0, f/2000), ...)

Value

When plot is FALSE, dfreq returns a two-column matrix, the first column corresponding to time in seconds (x-axis) and the second column corresponding to to dominant frequency in kHz (y-axis).

NA corresponds to pause sections in wave (see threshold).

Arguments

wave: an R object.
f: sampling frequency of wave (in Hz). Does not need to be specified if embedded in wave.
channel: channel of the R object, by default left channel (1).
wl: length of the window for the analysis (even number of points, by default = 512).
wn: window name, see ftwindow (by default "hanning").
ovlp: overlap between two successive analysis windows (in % ).
fftw: if TRUE calls the function FFT of the library fftw. See Notes of the spectro.
at: time position where the dominant frequency has to be computed (in s.).
tlim: modifications of the time X-axis limits.
threshold: amplitude threshold for signal detection (in % ).
bandpass: a numeric vector of length two, giving the lower and upper limits of a frequency bandpass filter (in Hz).
clip: a numeric value to select dominant frequency values according to their amplitude in reference to a maximal value of 1 for the whole signal (has to be >0 & < 1).
plot: logical, if TRUE plots the dominant 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.

Author

Jerome Sueur sueur@mnhn.fr

Examples

Run this code

data(tico)
f <- 22050
# default
dfreq(tico,f)
# using the amplitude threshold and changing the graphical output
dfreq(tico, f, ovlp=50,threshold=5, type="l", col=2)
# using 'at' argument for specific positions along the time axis
dfreq(tico, f, at=c(0.25, 0.75, 1.2, 1.6))
dfreq(tico, f, at=seq(0.5, 1.4, by=0.005), threshold=5)
# a specific number of measures on a single note
dfreq(tico, f, at=seq(0.5, 0.9, len=100), threshold=5, xlim=c(0.5,0.9))
# overlap on spectrogram
# and use of 'clip' argument to better track the dominant frequency
# in noisy conditions
op <- par()
ticon <- tico@left/max(tico@left) + noisew(d=length(tico@left)/f, f)
spectro(ticon, f)
res <- dfreq(ticon, f, clip=0.3, plot=FALSE)
points(res, col=2, pch =13)
par(op)