soundgen (version 1.5.0)

flatSpectrum: 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, freqWindow = NULL, samplingRate = NULL,
  dynamicRange = 80, windowLength = 50, step = NULL, overlap = 90,
  wn = "gaussian", zp = 0)

Arguments

x

path to a .wav or .mp3 file or a vector of amplitudes with specified samplingRate

freqWindow

the width of smoothing window, Hz. Defaults to median pitch estimated by analyze

samplingRate

sampling rate of x (only needed if x is a numeric vector, rather than an audio file)

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

overlap

overlap between successive FFT frames, %

wn

window type: gaussian, hanning, hamming, bartlett, rectangular, blackman, flattop

zp

window length after zero padding, points

Value

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

Examples

# NOT RUN {
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
sheep_orig = as.numeric(scale(sheep@left))
samplingRate = [e-mail]
playme(sheep_orig, samplingRate)
# spectrogram(sheep_orig, samplingRate)
# seewave::spec(sheep_orig, f = samplingRate, dB = 'max0')

sheep_flat = flatSpectrum(sheep_orig, freqWindow = 150,  # freqWindow ~f0
  samplingRate = samplingRate)
# playme(sheep_flat, samplingRate)
# spectrogram(sheep_flat, samplingRate)
# seewave::spec(sheep_flat, f = samplingRate, 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 = samplingRate,
  formants = 'aii',
  lipRad = -3)  # negative lipRad to counter unnatural flat source
playme(sheep_aii, samplingRate)
# spectrogram(sheep_aii, samplingRate)
# seewave::spec(sheep_aii, f = samplingRate, dB = 'max0')
# }