lfs {seewave} | R Documentation |
This function linearly shifts all the frequency content of a time wave.
lfs(wave, f, shift, wl = 128, wn = "hanning", output = "matrix")
wave |
an R object. |
f |
sampling frequency of wave (in Hz). Does not need to be specified if embedded in wave . |
shift |
positive or negative frequency shift to apply (in Hz).) |
wl |
window length for the analysis (even number of points, by default = 512). |
wn |
window name, see ftwindow (by default "hanning" ). |
output |
character string, the class of the object to return, either
"matrix" , "Wave" , "Sample" , "audioSample" or "ts" . |
A short-term Fourier transform is first applied to the signal
(see spectro
), then the frequency shift is applied and the new
signal is eventually generated using the reverse of the Fourier Transform
(fft
).
There is therefore neither temporal modifications nor
amplitude modifications.
If plot
is FALSE
, a new wave is returned. The class
of the returned object is set with the argument output
.
Jerome Sueur sueur@mnhn.fr and Thierry Aubin thierry.aubin@u-psud.fr
Hopp, S. L., Owren, M. J. and Evans, C. S. (Eds) 1998. Animal acoustic communication. Springer, Berlin, Heidelberg.
data(orni) a<-lfs(orni,f=22050,shift=1000) spectro(a,f=22050) # to be compared with the original signal spectro(orni,f=22050)