seewave (version 1.0)

meanspec: Mean frequency spectrum of a time wave

Description

This function returns the mean frequency spectrum (i.e. the mean relative amplitude of the frequency distribution) of a time wave. Results can be expressed either in absolute or dB data.

Usage

meanspec(wave, f, wl, ovlp = 0, PSD = FALSE, dB = FALSE,
from = FALSE, to = FALSE, peaks = FALSE, identify = FALSE,
col = "black", cex = 1, colpeaks = "red", cexpeaks = 1, 
fontpeaks = 1, plot = 1, flab = "Frequency (kHz)",
alab = "Amplitude", flim = c(0,f/2000),alim = NULL,...)

Arguments

wave

data describing a time wave.

f

sampling frequency of wave.

wl

length of the window for the analysis (even number of points).

ovlp

overlap between two successive analysis windows (in %).

PSD

if TRUE return Power Spectra Density, i. e. the square of the spectra.

dB

logical, if TRUE return the spectrum in dB (by default FALSE).

from

start mark where to compute the spectrum (in s).

to

end mark where to compute the spectrum (in s).

peaks

to return peaks values.

identify

to identify frequency values on the plot with the help of a cursor.

col

colour of the spectrum.

cex

pitch size.

colpeaks

colour of peaks value plotted on the spectrum.

cexpeaks

character size of peaks value plotted on the spectrum.

fontpeaks

font of peaks value plotted on the spectrum.

plot

if 1 returns frequency on x-axis, if 2 returns frequency on y-axis, (by default 1).

flab

title of the frequency axis.

alab

title of the amplitude axis.

flim

range of frequency axis.

alim

range of amplitude axis.

...

other plot graphical parameters.

Value

• If plot is FALSE, meanspec returns a vector of numeric data corresponding to the computed spectrum. If peaks is TRUE, spec returns a list with two elements:
• spec
  the spectrum computed
• peaks
  the peaks values (in kHz).

Details

A Hanning function is applied to the analysis window. If from and to are FALSE then spec computes the mean spectrum of the whole signal. peaks setting corresponds to dimension of embed. When using identify, press stop tools bar button to return values in the console.

See Also

spec, corspec, fft.

Examples

data(orni)
# compute the mean spectrum of the whole time wave
meanspec(orni,f=22050,wl=512,type="l")
# compute the mean spectrum of a time wave section (from 0.32 s to 0.39 s)
meanspec(orni,f=22050,wl=512,from=0.32,to=0.39,type="l")
# different window lengths
op<-par(mfrow=c(3,1))
meanspec(orni,f=22050,wl=256,type="l")
title("wl=256")
meanspec(orni,f=22050,wl=1024,type="l")
title("wl=1024")
meanspec(orni,f=22050,wl=4096,type="l")
title("wl=4096")
par(op)
# different overlap values (almost no effects here...)
op<-par(mfrow=c(3,1))
meanspec(orni,f=22050,wl=512,type="l")
title("ovlp=0")
meanspec(orni,f=22050,wl=512,ovlp=50,type="l")
title("ovlp=50")
meanspec(orni,f=22050,wl=512,ovlp=95,type="l")
title("ovlp=95")
par(op)
# use of flim to zoom in
op<-par(mfrow=c(2,1))
meanspec(orni,f=22050,wl=512,type="l")
title("zoom in")
meanspec(orni,f=22050,wl=512,type="l",flim=c(4,6))
par(op)
# comparaison of spectrum and mean spectrum
op<-par(mfrow=c(2,1))
spec(orni,f=22050,type="l")
title("spec()")
meanspec(orni,f=22050,wl=512,type="l")
title("meanspec()")
par(op)