flatSpectrum {soundgen}

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, rectangular, blackman, flattop

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.

See Also

addFormants transplantFormants

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, [e-mail])
seewave::spec(sheep_flat, f = [e-mail], 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 = [e-mail],
  formants = 'aii',
  lipRad = -3)  # negative lipRad to counter unnatural flat source
playme(sheep_aii, [e-mail])
spectrogram(sheep_aii, [e-mail])
seewave::spec(sheep_aii, f = [e-mail], dB = 'max0')

## End(Not run)