soundgen (version 2.3.0)

specToMS: Spectrogram to modulation spectrum

Description

Takes a spectrogram (either complex or magnitude) and returns a MS with proper row and column labels.

Usage

specToMS(spec, windowLength = NULL, step = NULL)

Arguments

spec

target spectrogram (numeric matrix, frequency in rows, time in columns)

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)

Value

Returns a MS - matrix of complex values of the same dimension as spec, with AM in rows and FM in columns.

Examples

# NOT RUN {
s = soundgen(sylLen = 500, 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')
abline(h = 0, lty = 3); abline(v = 0, lty = 3)
# }