seewave (version 1.5.5)

diffspec: Difference between two frequency spectra

Description

This function estimates the surface difference between two frequency spectra.

Usage

diffspec(spec1, spec2, f = NULL, dB = FALSE, plot = FALSE, type="l", 
lty1 = 1, lty2 = 2, col1 = 2, col2 = 4, cold = 8,
flab = "Frequency (kHz)", alab = "Amplitude",
flim = NULL, alim = NULL, legend = TRUE, ...)

Arguments

spec1

a first data set resulting of a spectral analysis obtained with spec or meanspec (not in dB). This can be either a two-column matrix (col1 = freque

spec2

a first data set resulting of a spectral analysis obtained with spec or meanspec (not in dB). This can be either a two-column matrix (col1 = freque

f

sampling frequency of waves used to obtain spec1 and spec2 (in Hz). Not necessary if spec1 and/or spec2 is a two-column matrix obtained with spec

dB

logical, if TRUE return the spectra and their surface difference in dB (by default FALSE).

plot

logical, if TRUE plots both spectra and their surface difference (by default FALSE).

type

if plot is TRUE, type of plot that should be drawn. See plot for details (by default "l" for lines).

lty1

line type of spec1 if type="l".

lty2

line type of spec2 if type="l".

col1

colour of spec1.

col2

colour of spec2.

cold

colour of the surface difference.

flab

title of the frequency axis.

alab

title of the amplitude axis.

flim

the range of frequency values.

alim

range of amplitude axis.

legend

logical, if TRUE adds a legend to the plot.

...

other plot graphical parameters.

Value

• The difference is returned. This value is without unit. If dB is TRUE, the same value is returned in dB. When plot is TRUE, both spectra and their difference surface are plotted on the same graph.

Details

Both spectra are first transformed as probability mass functions (PMF). Spectral difference is then computed according to: $$D = \frac{\sum{|spec1-spec2|}}{2}, with D \in [0,1].$$ with 0 < D

References

Sueur, J., Pavoine, S., Hamerlynck, O. and Duvail, S. (2008). Rapid acoustic survey for biodiversity appraisal. PLoS One, 3(12): e4065.

See Also

spec, meanspec, corspec, simspec, diffenv

Examples

a<-noise(f=8000,d=1)
b<-synth(f=8000,d=1,cf=2000)
c<-synth(f=8000,d=1,cf=1000)
d<-noise(f=8000,d=1)
speca<-spec(a,f=8000,wl=512,at=0.5,plot=FALSE)
specb<-spec(b,f=8000,wl=512,at=0.5,plot=FALSE)
specc<-spec(c,f=8000,wl=512,at=0.5,plot=FALSE)
specd<-spec(d,f=8000,wl=512,at=0.5,plot=FALSE)
diffspec(speca,speca,f=8000)
#[1] 0 => similar spectra of course !
diffspec(speca,specb)
diffspec(speca,specc,plot=TRUE)
diffspec(specb,specc,plot=TRUE)
diffspec(speca,specd,plot=TRUE)