smoothw {seewave}

A function to tentativily smooth a time wave

Description

This function tries to smooth with a sum sliding window a time wave, and then to remove residual noise.

Usage

smoothw(wave, f, channel = 1, wl, padding=TRUE, output = "matrix")

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

window length in number of points (samples).

padding

a logical, if TRUE add 0 values at the start and end of the file to match wave length (duration).

output

character string, the class of the object to return, either "matrix", "Wave", "Sample", "audioSample" or "ts".

Details

A window slides along the signal and sums up the sample amplitude values. Zero values are added at the end of the wave to keep wave length (duration).

Value

A new wave is returned. The class of the returned object is set with the argument output. If padding is TRUE, the new wave starts and ends up with 0 values to match the size of wave.

Warning

This function should be used with care as this kind of filter may change the frequency content of the sound. See the examples section for an illustration.

Author(s)

Jerome Sueur

See Also

fir, filter

Examples

# An example to show that smoothw() may change
# the frequency content of your sound
data(orni)
orni2 <- smoothw(orni, wl=2, out="Wave")
orni10 <- smoothw(orni, wl=10, out="Wave")
orni50 <- smoothw(orni, wl=50, out="Wave")
orni100 <- smoothw(orni, wl=100, out="Wave")
meanspec(orni)
lines(meanspec(orni2, plot=FALSE), col=2)
lines(meanspec(orni10, plot=FALSE), col=3)
lines(meanspec(orni50, plot=FALSE), col=4)
lines(meanspec(orni100, plot=FALSE), col=5)
legend("topright", col=1:5, lty=1, legend=c("original","wl=2","wl=10","wl=50","wl=100"))