seewave (version 1.4.5)

diffspec: Difference between two frequency spectra

Description

This function estimates the surface difference between two frequency spectra.

Usage

diffspec(spec1, spec2, f, dB = FALSE, plot = FALSE, type="l", 
lty1 = 1, lty2 = 2, col1 = 2, col2 = 4, cold = 8,
flab = "Frequency (kHz)", alab = "Amplitude",
flim = c(0, f/2000), alim = c(0,max(spec1,spec2)),...)

Arguments

spec1

a first data set resulting of a spectral analysis obtained with spec or meanspec (not in dB).

spec2

a second data set resulting of a spectral analysis obtained with spec or meanspec (not in dB).

f

sampling frequency of waves used to obtain spec1 and spec2 (in Hz).

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.

...

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: $$D = \sum{|spec1-spec2|}, with D \in [0,1].$$

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,f=8000)
#[1] 0.965465
diffspec(speca,specc,f=8000,plot=TRUE)
#[1] 0.95498
# two pure tone at different frequency are...
diffspec(specb,specc,f=8000,plot=TRUE)
#[1] 0.9999166
#... more different than two noises
diffspec(speca,specd,f=8000,plot=TRUE)
#[1] 0.2810392