lfs {seewave} | R Documentation |
This function linearly shifts all the frequency content of a time wave.
lfs(wave, f, shift, wl = 128, wn = "hanning", Sample = FALSE)
wave |
data describing a time wave
or a Sample object generated loading a wav file
with loadSample (package sound). |
f |
sampling frequency of wave (in Hz).
Does not need to be specified if wave is a Sample object. |
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" ). |
Sample |
if TRUE and plot is FALSE
returns an object of class Sample |
.
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 as a one-column matrix
or as a Sample
object if Sample
is TRUE
.
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)