seewave (version 1.1)

Q: Resonance quality factor of a frequency spectrum

Description

This function estimates the frequency pureness of a time wave by returning the resonant quality factor Q at a specific dB level.

Usage

Q(x, range, level = -3, plot = TRUE, colval = "red",
cexval = 1, fontval = 1, flab = "Frequency (kHz)",
alab = "Relative amplitude (dB)",...)

Arguments

x

a data set resulting of a spectral analysis obtained with spec, or meanspec (in dB).

range

range of x (in kHz).

level

frequency bandwidth set by an amplitude value relative to spectrum (in dB).

plot

logical, if TRUE returns the spectrum with Q plotted (by default TRUE).

colval

colour of plotting Q.

cexval

character size of plotting Q.

fontval

font of plotting Q.

flab

title of the frequency axis.

alab

title of the ampltiude axis.

...

other plot graphical parameters.

Value

• Q is returned as a single numeric data.

Details

A high Q value indicates a highly resonant system.

See Also

spec, meanspec, corspec, fft.

Examples

# bird song
data(tico)
t<-spec(tico,f=22050,wl=512,at=1.1,plot=FALSE,dB=TRUE)
op<-par(mfrow=c(2,1),las=1)
Q(t,range=c(0,11.025),type="l")
Q(t,range=c(0,11.025),type="l",xlim=c(3.8,4.2),ylim=c(-60,0))
title("zoom in")
par(op)
# cricket, changing the dB level
data(pellucens)
p<-spec(pellucens,f=11025,wl=512,at=0.5,plot=FALSE,dB=TRUE)
op<-par(mfrow=c(3,1))
Q(p,range=c(0,11.25/2),type="l",xlim=c(1.8,2.6),ylim=c(-70,0))
title("level = - 3 (default value)",col.main="red")
Q(p,range=c(0,11.25/2),type="l",level=-6,
    xlim=c(1.8,2.6),ylim=c(-70,0),colval="blue")
title("level = - 6",col.main="blue")
Q(p,range=c(0,11.25/2),type="l",level=-9,
    xlim=c(1.8,2.6),ylim=c(-70,0),colval="green")
title("level = - 9",col.main="green")
par(op)