soundgen (version 2.7.0)

msToSpec: Modulation spectrum to spectrogram

Description

Takes a complex MS and transforms it to a complex spectrogram with proper row (frequency) and column (time) labels.

Usage

msToSpec(ms, windowLength = NULL, step = NULL)

Value

Returns a spectrogram - a numeric matrix of complex numbers of the same dimensions as ms.

Arguments

ms

target modulation spectrum (matrix of complex numbers)

windowLength

length of FFT window, ms

step

you can override overlap by specifying FFT step, ms (NB: because digital audio is sampled at discrete time intervals of 1/samplingRate, the actual step and thus the time stamps of STFT frames may be slightly different, eg 24.98866 instead of 25.0 ms)

Examples

s = soundgen(sylLen = 250, amFreq = 25, amDep = 50,
             pitch = 250, samplingRate = 16000)
spec = spectrogram(s, samplingRate = 16000, windowLength = 25, step = 5)
ms = specToMS(spec)
image(x = as.numeric(colnames(ms)), y = as.numeric(rownames(ms)),
      z = t(log(abs(ms))), xlab = 'Amplitude modulation, Hz',
      ylab = 'Frequency modulation, cycles/kHz')
spec_new = msToSpec(ms)
image(x = as.numeric(colnames(spec_new)), y = as.numeric(rownames(spec_new)),
      z = t(log(abs(spec_new))), xlab = 'Time, ms',
      ylab = 'Frequency, kHz')