env {seewave}R Documentation

Amplitude envelope of a time wave

Description

This function returns the absolute or Hilbert amplitude envelope of a time wave.

Usage

env(wave, f, envt = "hil", msmooth = NULL,
ksmooth = NULL, plot = TRUE, k = 1, j = 1, ...)

Arguments

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.
envt the type of envelope to be returned: either "abs" for absolute amplitude envelope or "hil" for Hilbert amplitude envelope. See Details section.
msmooth a vector of length 2 to smooth the amplitude envelope with a mean sliding window. The first component is the window length (in number of points). The second component is the overlap between successive windows (in %). See examples.
ksmooth kernel smooth via kernel. See examples.
plot logical, if TRUE returns a plot of wave envelope (by default TRUE).
k number of horizontal sections when plot is TRUE (by default =1).
j number of vertical sections when plot is TRUE (by default =1).
... other oscillo graphical parameters.

Details

When envt is set as "abs", the amplitude envelope returned is the absolute value of wave.
When envt is set as "hil", the amplitude envelope returned is the modulus (Mod) of the analytical signal of wave obtained through the Hilbert transform (hilbert).

Value

Data are returned as one-column matrix when plot is FALSE.

Note

Be aware that smoothing with either msmooth or ksmooth changes the original number of points describing wave.

Author(s)

Jerome Sueur sueur@mnhn.fr

See Also

oscillo,hilbert

Examples

data(tico)
# Hilbert amplitude envelope
env(tico,f=22050)
# absolute amplitude envelope
env(tico,f=22050,envt="abs")
# smoothing with a 10 points and 50
env(tico,f=22050,msmooth=c(10,50))
# smoothing kernel
env(tico,f=22050,ksmooth=kernel("daniell",10))
# overplot of oscillographic and envelope representations
oscillo(tico,f=22050)
par(new=TRUE)
env(tico,f=22050,colwave=2)

[Package seewave version 1.5.0 Index]