| spec {seewave} | R Documentation |
This function returns the frequency spectrum (i.e. the relative amplitude of the frequency content) of a time wave. Results can be obtained either as absolute or dB data.
spec(wave, f, wl = 512, wn = "hanning", PSD = FALSE, PMF = FALSE, dB = FALSE, at = NULL, from = NULL, to = NULL, 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, type="l",...)
wave |
data describing a time wave or a Sample
object generated loading a wav file with loadSample
(package sound). |
f |
sampling frequency of wave (in Hz).
Does not need to be specified if wave is a Sample object. |
wl |
if at is not null, length of the window for the analysis
(even number of points, by defaults = 512). |
wn |
window name, see ftwindow (by default "hanning"). |
PSD |
if TRUE return Power Spectra Density,
i. e. the square of the spectra. |
PMF |
if TRUE return Probability Mass Function,
i. e. the probability distribution of frequencie. |
dB |
logical, if TRUE returns the spectrum in dB
(by default FALSE). |
at |
position where to compute the spectrum (in s). |
from |
start mark where to compute the spectrum (in s). |
to |
end mark where to compute the spectrum (in s). |
peaks |
returns peaks value for a given span (see details). |
identify |
to identify frequency and amplitude values on the plot with the help of a cursor. |
col |
colour of the spectrum. |
cex |
pitch size of the spectrum. |
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. |
type |
if plot is TRUE, type of plot that should be drawn.
See plot for details (by default "l" for lines). |
... |
other plot graphical parameters. |
If at, from or to are FALSE then spec
computes the 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.
This function returns a two-column matrix,
the first column corresponding to the frequency axis, the second column
corresponding to the amplitude axis.
If identify is TRUE, spec returns a list with
two elements:
freq |
the frequency of the points chosen on the spectrum |
amp |
the relative amplitude of the points chosen on the spectrum |
spec |
the spectrum computed |
peaks |
the peaks value (in kHz). |
This function is based on fft.
Jerome Sueur sueur@mnhn.fr and
Martin Maechler maechler@stat.math.ethz.ch for peaks.
meanspec, dynspec,
corspec, fft.
data(tico)
# spectrum of the whole signal, in absolute or dB amplitude,
# horizontaly or vertically
op<-par(mfrow=c(2,2))
spec(tico,f=22050)
spec(tico,f=22050,col="red",plot=2)
spec(tico,f=22050,dB=TRUE,col="blue")
spec(tico,f=22050,dB=TRUE,col="green",plot=2)
par(op)
# spectra computed at specific locations with peak value
op<-par(mfrow=c(2,2))
spec(tico,f=22050,wl=512,at=0.2,peak=175)
title("Note A")
spec(tico,f=22050,wl=512,at=0.7,peak=175)
title("Note B")
spec(tico,f=22050,wl=512,at=1.1,peak=175)
title("Note C")
spec(tico,f=22050,wl=512,at=1.6,peak=165)
title("Note D")
par(op)
# an indirect way to compare spectra
a<-spec(tico,f=22050,wl=512,at=0.2,plot=FALSE)
b<-spec(tico,f=22050,wl=512,at=0.7,plot=FALSE)
c<-spec(tico,f=22050,wl=512,at=1.1,plot=FALSE)
d<-spec(tico,f=22050,wl=512,at=1.6,plot=FALSE)
all<-cbind(a[,2],b[,2],c[,2],d[,2])
matplot(x=a[,1],y=all,yaxt="n",
xlab="Frequency (kHz)",ylab="Amplitude",xaxs="i",type="l")
legend(8,0.8,c("Note A","Note B", "Note C", "Note D"),bty="o",
lty=c(1:4),col=c(1:4))
# spectrum from a particular position to another one
op<-par(mfrow=c(2,1))
oscillo(tico,f=22050)
abline(v=c(0.5,0.9),col="red",lty=2)
text(c("from 0.5 s","to 0.7 s"),
x=c(0.5,0.9),y=rep(max(tico/1.1),2),col="red",pos=4)
spec(tico,f=22050,wl=512,from=0.5,to=0.9,col="red")
title("Spectrum of the note B")
par(op)
# spectrum and spectrogram
data(orni)
orni1<-cutw(orni,f=22050,from=0.32,to=0.39)
layout(matrix(c(1,2),nc=2),widths=c(3,1))
par(mar=c(5,4,3,0.5))
spectro(orni1,f=22050,wl=128,zp=8,ovlp=85,scale=FALSE)
par(mar=c(5,1,3,0.5))
spec(orni1,f=22050,col="red",plot=2,flab="",yaxt="n")