| localpeaks {seewave} | R Documentation |
This functions searches for local peaks of a frequency spectrum
localpeaks(spec, f = NULL, bands = 10, mel = FALSE, plot = TRUE, xlab = NULL, ylab = "Amplitude", labels = TRUE, ...)
spec |
a data set resulting of a spectral analysis obtained
with |
f |
sampling frequency of |
bands |
a numeric vector. If vector of length 1, then sets the number of bands dividing in equal parts the spectrum. If of length > 1, then takes the values as kHz limits of the bands dividing the spectrum. These bands can be of different size. See details and examples. |
mel |
a logical, if |
plot |
logical, if |
xlab |
label of the x-axis. |
ylab |
label of the y-axis. |
labels |
logical, if |
... |
other |
The function proceed as follows
divides the spectrum in bands. The limits of the bands are set
with the argument bands. There are two options:
you set a number of bands with equal size by giving a single
value to bands. For instance, setting bands to a value
of 10 will slice the spectrum in 10 equal parts and return 10 local
peaks.
you set the limits of the bands. This is achieve by giving a
numeric vector to bands. The limits can follow a regular or
irregular series. For instance attributing the vector c(0,2,4,8) will
generate the following bands [0,2[, [2,4[, [4,8] kHz. Be aware that
the last value should not exceed half the sampling frequency used to
obtain the spectrum spec.
uses the function fpeaks with the argument
nmax set to 1.
A two-column matrix, the first column corresponding to the frequency values (x-axis) and the second column corresponding to the amplitude values (y-axis) of the peaks.
Jerome Sueur
data(sheep) spec <- meanspec(sheep, f=8000) # a specific number of bands with all the same size localpeaks(spec, bands=5) # bands directly specified with a regular sequence localpeaks(spec, bands=seq(0,8/2,by=0.5)) # bands directly specified with an irregular sequence localpeaks(spec, bands=c(0,0.5,1,1.5,3,4)) # Amaj octave bands, note that there is no peak detection # in the higher part of the spectrum as sequence stops at 3520 Hz localpeaks(spec, bands=octaves(440, below=3, above=3)/1000) # melscale require(tuneR) mel <- melfcc(sheep, nbands = 256, dcttype = "t3", fbtype = "htkmel", spec_out=TRUE) melspec.mean <- apply(mel$aspectrum, MARGIN=2, FUN=mean) melspec.mean <- melspec.mean/max(melspec.mean) # [0,1] scaling localpeaks(melspec.mean, f=8000, bands=8)