echo {seewave}

Echo generator

Description

This function generate echoes of a time wave.

Usage

echo(wave, f, channel = 1, amp, delay, plot = FALSE,
listen = FALSE, 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).

amp

a vector describing the relative amplitude of the successive echoes. Each value of the vector should be in [0,1]

delay

a vector describing the time delays of the successive echoes from the beginning of wave (in s.)

plot

logical, if TRUE returns an oscillographic plot of the wave modified (by default FALSE).

listen

if TRUE the new sound is played back.

output

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

...

other oscillo graphical parameters.

Details

amp and delay should strictly have the same length corresponding to the number of desired echoes.

Value

If plot is FALSE, a new wave is returned. The class of the returned object is set with the argument output.

Note

This function is based on a convolution (convolve) between the input wave and a pulse echo filter.

Author(s)

Jerome Sueur [e-mail]

References

Stoddard, P. K. (1998). Application of filters in bioacoustics. In: Hopp, S. L., Owren, M. J. and Evans, C. S. (Eds), Animal acoustic communication. Springer, Berlin, Heidelberg,pp. 105-127.

See Also

synth

Examples

# generation of the input wave
a <- synth(f=11025,d=1,cf=2000,shape="tria",am=c(50,10),fm=c(1000,10,1000,0,0))
# generation of three echoes
# with respectively a relative amplitude of 0.8, 0.4, and 0.2
# and with a delay of 1s, 2s, and 3s  from the beginning of the input wave
aecho <- echo(a,f=11025,amp=c(0.8,0.4,0.2),delay=c(1,2,3))
# another echo with time delays overlapping with the input wave
aecho <- echo(a,f=11025,amp=c(0.4,0.2,0.4),delay=c(0.6,0.8,1.5))