phonTools (version 0.1-4)

spectralslice: Plot the Spectrum of a Vector

Description

A function to plot the magnitude spectrum of a vector representing a sound wave.

Usage

spectralslice (sound, padding = length(sound)*2, fs = 22050, output = FALSE, 
show = TRUE, color = 1, add = FALSE, xlim, ylim, window = 'kaiser', 
windowparameter = 4, zeromax = TRUE, preemphasis = 50000, type, xlab, pwr = TRUE, ...)

Arguments

sound

A vector representing a sequence of samples taken at equal time intervals. Each sample should indicate the amplitude of the wave at that time interval.

padding

The amount of zero-padding desired for the analysis.

fs

The sampling frequency of the sound.

output

If TRUE, the frequency of bin centers and power at those centers is returned.

show

If FALSE, no plot is created.

color

Set the color used for plotting the spectrum.

add

If TRUE, the spectrum is added to an existing plot. If FALSE a new one is created.

xlim

The range of frequencies to be plotted. By default the function will plot from 0 Hz to fs/2 Hz.

ylim

The y axis (power/magnitude) range to plot.

window

The window to be applied to the signal, applied by windowfunc(), provided in this package.

windowparameter

The parameter for the window to be applied to the signal, if appropriate. Passed to windowfunc().

zeromax

If TRUE, the maximum dB is set to 0.

type

The line type to be used for plotting, passes its value to the 'lty' parameter.

preemphasis

Preemphasis of 6 dB per octave is added to frequencies above the specified frequency. For no preemphasis, set to a frequency higher than the sampling frequency.

xlab

the x-axis label may be specified if desired.

pwr

If TRUE, a power spectrum is calculated, if FALSE, a magnitude spectrum is calculated.

...

any additional arguments will be passed to the internal calls of 'plot' or 'lines'.

Value

• If output is set to TRUE, a dataframe with the following elements is returned:
• hz
  The center frequency of the analysis bins.
• amp
  The dB amplitude for the analysis bin.

Details

This function can be used to calculate and plot short-time frequency spectra for sections of signals.

Examples

data (sound)
par (mfrow = c(2,2))

spectralslice (sound$sound[1:100], padding = 0, xlim = c(0,5000), 
          main = 'few points, no padding')
spectralslice (sound$sound[1:600], padding = 0, xlim = c(0,5000), 
          main = 'many points, no padding')

spectralslice (sound$sound[1:100], padding = 5000, xlim = c(0,5000), 
          main = 'few points, with padding')
spectralslice (sound$sound[1:600], padding = 50000, xlim = c(0,5000), 
          main = 'many points, with padding')