soundgen (version 2.7.2)

noiseRemoval: Noise removal

Description

Removes noise by spectral substraction. If a recording is affected by a steady noise with a relatively stable amplitude and spectrum (e.g., microphone hiss, crickets, MRI buzz, etc.), its spectrum can be simply subtracted from the signal. Algorithm: STFT to produce a spectrogram, divide by normalized noise spectrum, inverse STFT to reconstitute the signal. Most of the work is done by addFormants.

Usage

noiseRemoval(
  x,
  samplingRate = NULL,
  scale = NULL,
  noise,
  dB = 6,
  specificity = 1,
  windowLength = 50,
  step = windowLength/2,
  dynamicRange = 120,
  normalize = c("max", "orig", "none")[2],
  reportEvery = NULL,
  cores = 1,
  play = FALSE,
  saveAudio = NULL,
  plot = FALSE,
  savePlots = NULL,
  width = 900,
  height = 500,
  units = "px",
  res = NA,
  ...
)

Value

Returns the denoised audio

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)

scale

maximum possible amplitude of input used for normalization of input vector (only needed if x is a numeric vector)

noise

a numeric vector of length two specifying the location of pure noise in input audio (in s); a matrix representing pure noise as a spectrum with frequency bins in rows; any input accepted by spectrogram if pure noise is found in a separate recording (eg path to file, numeric vector, etc.)

dB

if NULL (default), the spectral envelope is applied on the original scale; otherwise, it is set to range from 1 to 10 ^ (dB / 20)

specificity

a way to sharpen or blur the noise spectrum (we take noise spectrum ^ specificity) : 1 = no change, >1 = sharper (the loudest noise frequencies are preferentially removed), <1 = blurred (even quiet noise frequencies are removed)

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)

dynamicRange

dynamic range, dB. All values more than one dynamicRange under maximum are treated as zero

normalize

if TRUE, scales input prior to FFT

reportEvery

when processing multiple inputs, report estimated time left every ... iterations (NULL = default, NA = don't report)

cores

number of cores for parallel processing

play

if TRUE, plays the synthesized sound using the default player on your system. If character, passed to play as the name of player to use, eg "aplay", "play", "vlc", etc. In case of errors, try setting another default player for play

saveAudio

path + filename for saving the output, e.g. '~/Downloads/temp.wav'. If NULL = doesn't save

plot

should a spectrogram be plotted? TRUE / FALSE

savePlots

full path to the folder in which to save the plots (NULL = don't save, '' = same folder as audio)

width, height, units, res

graphical parameters for saving plots passed to png

...

other graphical parameters

See Also

addFormants

Examples

s = soundgen(noise = list(time = c(-100, 400), value = -20),
  formantsNoise = list(f1 = list(freq = 3000, width = 25)),
  addSilence = 50, temperature = .001, plot = TRUE)
# Option 1: use part of the recording as noise profile
s1 = noiseRemoval(s, samplingRate = 16000, noise = c(0.05, 0.15),
  dB = 40, plot = TRUE)

# Option 2: use a separate recording as noise profile
noise = soundgen(pitch = NA, noise = 0,
  formantsNoise = list(f1 = list(freq = 3000, width = 25)))
spectrogram(noise, 16000)
s2 = noiseRemoval(s, samplingRate = 16000, noise = noise,
  dB = 40, plot = TRUE)

# Option 3: provide noise spectrum as a matrix
spec_noise = spectrogram(
      noise, samplingRate = 16000,
      output = 'original', plot = FALSE)
s3 = noiseRemoval(s, samplingRate = 16000, noise = spec_noise,
  dB = 40, plot = TRUE)

if (FALSE) {
# play with gain and sensitivity
noiseRemoval(s, samplingRate = 16000, noise = c(0.05, 0.15),
  dB = 60, specificity = 2, plot = TRUE)

# remove noise only from a section of the audio
noiseRemoval(s, samplingRate = 16000, from = .3, to = .4,
  noise = c(0.05, 0.15), dB = 60, plot = TRUE, play = TRUE)
}