R: Difference between two cumulative frequency spectra

diffcumspec {seewave}

R Documentation

Difference between two cumulative frequency spectra

Description

This function compares two distributions (e.g. two frequency spectra) by computing the difference between two cumulative frequency spectra

Usage

diffcumspec(spec1, spec2, f = NULL, mel = FALSE, 
plot = FALSE, type = "l", lty = c(1, 2), col = c(2, 4, 8),
flab = NULL, alab = "Cumulated amplitude",
flim = NULL, alim = NULL,
title = TRUE, legend = TRUE, ...)

Arguments

`spec1`	any distribution, especially a spectrum obtained with `spec` or `meanspec` (not in dB). This can be either a two-column matrix (col1 = frequency, col2 = amplitude) or a vector (amplitude).
`spec2`	any distribution, especially a spectrum obtained with `spec` or `meanspec` (not in dB). This can be either a two-column matrix (col1 = frequency, col2 = amplitude) or a vector (amplitude).
`f`	sampling frequency of waves used to obtain `spec1` and `spec2` (in Hz). Not necessary if `spec1` and/or `spec2` is a two columns matrix obtained with `spec` or `meanspec`.
`mel`	a logical, if `TRUE` the (htk-)mel scale is used.
`plot`	logical, if `TRUE` plots both cumulative spectra and their distance.
`type`	if `plot` is `TRUE`, type of plot that should be drawn. See `plot` for details (by default "l" for lines).
`col`	a vector of length 3 for the colour of `spec1`, `spec2`, and the difference between each of them.
`lty`	a vector of length 2 for the line type of `spec1` and `spec2` if `type`="l".
`flab`	title of the frequency axis.
`alab`	title of the amplitude axis.
`flim`	the range of frequency values.
`alim`	range of amplitude axis.
`title`	logical, if `TRUE`, adds a title with D and F values.
`legend`	logical, if `TRUE` adds a legend to the plot.
`...`	other `plot` graphical parameters.

Details

Both spectra are transformed into cumulative distribution functions (CDF).
Spectral difference is then computed according to:

D = 1/n * sum(abs(X-Y)), with X and Y the spectrum CDFs, and 0 < D < 1.

Value

A numeric vector of length 1 returning the difference between the two spectra. No unit.

Note

This metric is sensitive not only to the spectral overlap between but also to the mean frequential distance between the different frequency peaks.

Author(s)

Laurent Lellouch, Jerome Sueur

References

Lellouch L, Pavoine S, Jiguet F, Glotin H, Sueur J (2014) Monitoring temporal change of bird communities with dissimilarity acoustic indices. Methods in Ecology and Evolution, in press.

Examples

## Hz scale
data(tico)
data(orni)
orni.hz <- meanspec(orni, plot=FALSE)
tico.hz <- meanspec(tico, plot=FALSE)
diffcumspec(orni.hz, tico.hz, plot=TRUE)
## mel scale
require(tuneR)
orni.mel <- melfcc(orni, nbands = 256, dcttype = "t3", fbtype = "htkmel", spec_out=TRUE)
orni.mel.mean <- apply(orni.mel$aspectrum, MARGIN=2, FUN=mean)
tico.mel <- melfcc(tico, nbands = 256, dcttype = "t3", fbtype = "htkmel", spec_out=TRUE)
tico.mel.mean <- apply(tico.mel$aspectrum, MARGIN=2, FUN=mean)
diffcumspec(orni.mel.mean, tico.mel.mean, f=22050, mel=TRUE, plot=TRUE)

[Package seewave version 2.1.6 Index]