R: Spectral flux

specflux {seewave}

R Documentation

Spectral flux

Description

Compute spectral flux

Usage

specflux(wave, f, channel = 1,
         wl = 512, ovlp = 0, wn = "rectangle", flim = NULL,
         norm = FALSE,  p = 2,
         plot = TRUE, xlab = "Times (s)", ylab = "Flux", type = "l", ...)

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 for the analysis (even number of points) (by default = 512).
`ovlp`	overlap between two successive windows (in %).
`wn`	window name, see `ftwindow` (by default `"rectangle"`).
`flim`	a numeric vector of length 2 to select a frequency band (in kHz).
`norm`	if is `TRUE` then the normalised spectra are used. The spectra are normalised by their sum.
`p`	the norm type, by default = 2.
`plot`	logical, if `TRUE` the spectral flux is displayed against time (s) (by default `TRUE`).
`xlab`	title of the x axis.
`ylab`	title of the y axis.
`type`	if `plot` is `TRUE`, type of plot that should be drawn. See `plot` for details (by default "l" for lines).
`...`	other `plot` parameters.

Details

The spectral flux (F) is the sum of the time (t) derivative of the columns – that is the successive spectra – (s) of the normalized short-term Fourier transform (z).
F is then computed according to:

F = rowSums(abs(diff(t(z)))^p)^(1/p)

Value

When plot is FALSE, specflux returns a two-column matrix, the first column being time in seconds (x-axis) and the second column being the spectral flux (y-axis) computed along time.

Note

The sum of the successive spectral flux values could be used as an ecoacoustic index, quite close to the acoustic complexity index (ACI). See examples.

Author(s)

Jérôme Sueur

References

Scheirer E, Slaney M (1997). Construction and evaluation of a robust multifeature speech/music discriminator. IEEE International Conference on Acoustics, Speech, and Signal Processing, 2, 1221-1224.

Examples

## default use
data(tico)
specflux(tico)
## norm 1
specflux(tico, p = 1)
## frequency limit between 2 and 4 kHz
specflux(tico, flim = c(2,4))
## index computation
sum(specflux(tico, plot=FALSE)[,2])

[Package seewave version 2.1.6 Index]