flatSpectrum: Flat spectrum
In soundgen: Sound Synthesis and Acoustic Analysis

flatSpectrum

R Documentation

Flat spectrum

Description

Flattens the spectrum of a sound by smoothing in the frequency domain. Can be used for removing formants without modifying pitch contour or voice quality (the balance of harmonic and noise components), followed by the addition of a new spectral envelope (cf. transplantFormants). Algorithm: makes a spectrogram, flattens the real part of the smoothed spectrum of each STFT frame, and transforms back into time domain with inverse STFT (see also addFormants).

Usage

flatSpectrum(
  x,
  samplingRate = NULL,
  freqWindow = NULL,
  dynamicRange = 80,
  windowLength = 50,
  step = NULL,
  overlap = 90,
  wn = "gaussian",
  zp = 0,
  play = FALSE,
  saveAudio = NULL,
  reportEvery = NULL,
  cores = 1
)

Arguments

`x`	path to a folder, one or more wav or mp3 files c('file1.wav', 'file2.mp3'), Wave object, numeric vector, or a list of Wave objects or numeric vectors
`samplingRate`	sampling rate of `x` (only needed if `x` is a numeric vector)
`freqWindow`	the width of smoothing window, Hz. Defaults to median pitch estimated by `analyze`
`dynamicRange`	dynamic range, dB. All values more than one dynamicRange under maximum are treated as zero
`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)
`overlap`	overlap between successive FFT frames, %
`wn`	window type accepted by `ftwindow`, currently gaussian, hanning, hamming, bartlett, blackman, flattop, rectangle
`zp`	window length after zero padding, points
`play`	if TRUE, plays the processed audio
`saveAudio`	full (!) path to folder for saving the processed audio; NULL = don't save, ” = same as input folder (NB: overwrites the originals!)
`reportEvery`	when processing multiple inputs, report estimated time left every ... iterations (NULL = default, NA = don't report)
`cores`	number of cores for parallel processing

Value

Returns a numeric vector with the same sampling rate as the input.

Examples

sound_aii = soundgen(formants = 'aii')
# playme(sound_aii, 16000)
seewave::meanspec(sound_aii, f = 16000, dB = 'max0')

sound_flat = flatSpectrum(sound_aii, freqWindow = 150, samplingRate = 16000)
# playme(sound_flat, 16000)
seewave::meanspec(sound_flat, f = 16000, dB = 'max0')
# harmonics are still there, but formants are gone and can be replaced

## Not run: 
# Now let's make a sheep say "aii"
data(sheep, package = 'seewave')  # import a recording from seewave
playme(sheep)
sheep_flat = flatSpectrum(sheep)
playme(sheep_flat, sheep@samp.rate)
seewave::spec(sheep_flat, f = sheep@samp.rate, dB = 'max0')

# So far we have a sheep bleating with a flat spectrum;
# now let's add new formants
sheep_aii = addFormants(sheep_flat,
  samplingRate = sheep@samp.rate,
  formants = 'aii',
  lipRad = -3)  # negative lipRad to counter unnatural flat source
playme(sheep_aii, sheep@samp.rate)
spectrogram(sheep_aii, sheep@samp.rate)
seewave::spec(sheep_aii, f = sheep@samp.rate, dB = 'max0')

## End(Not run)

soundgen documentation built on Sept. 12, 2024, 6:29 a.m.