soundgen (version 1.0.0)

generateNoise: Generate noise

Description

Internal soundgen function.

Usage

generateNoise(len, noiseAnchors = data.frame(time = c(0, 300), value = c(-120,
  -120)), rolloffNoise = -6, attackLen = 10, windowLength_points = 1024,
  samplingRate = 16000, overlap = 75, throwaway = -120,
  filterNoise = NA)

Arguments

len

length of output

noiseAnchors

a dataframe specifying the amplitude envelope of output. $time: timing of aspiration noise, ms c(start,finish) relative to voiced part, eg c(-100,500) means breathing starts 100 ms before the voiced part and lasts until 500 ms into the voiced part (eg total duration of breathing = 500 - (-100) = 600 ms). noiseAnchors$value: the amount of aspiration noise at the given time anchors (to be smoothed). throwaway = no breathing, 0 = as strong as the voiced (harmonic) part

rolloffNoise

rolloff of noise, dB/octave. It is analogous to rolloff, but while rolloff applies to the harmonic component, rolloffNoise applies to the noise component

attackLen

duration of fade-in / fade-out at each end of syllables and noise (ms)

windowLength_points

the length of fft window, points

samplingRate

sampling frequency, Hz

overlap

FFT window overlap, %

throwaway

discard harmonics and noise that are quieter than this number (in dB, defaults to -120) to save computational resources

filterNoise

(optional): in addition to using rolloffNoise, we can provide the exact filter - a vector of length windowLength_points/2 or, if we want moving formants, a matrix with windowLength_points/2 rows and an arbitrary number of columns

Details

Generates white noise of length len and with spectrum defined by exponential decay rolloffNoise and/or a specified filter filterNoise. Algorithm: paints a spectrum with desired characteristics, sets phase to zero, and generates a time sequence via inverse FFT. Noise can then be used as an additional source to be added to the glottal source AFTER the glottal source has been formant-filtered, or BEFORE formant-filtering for glottal breathing noise.

Examples

# NOT RUN {
# 1 s of white noise
samplingRate = 16000
noise = soundgen:::generateNoise(len = samplingRate,
  rolloffNoise = 0, samplingRate = samplingRate)
# playme(noise, samplingRate = samplingRate)
# 1 s of noise with rolloff -6 dB
noise = soundgen:::generateNoise(len = samplingRate,
  rolloffNoise = -6, samplingRate = samplingRate)

# To create a sibilant [s], specify a single strong, broad formant at ~7 kHz:
windowLength_points = 1024
filterNoise = soundgen:::getSpectralEnvelope(
  nr = windowLength_points / 2, nc = 1, samplingRate = samplingRate,
 formants = list('f1' = data.frame(time = 0, freq = 7000,
                                   amp = 50, width = 2000)))
noise = soundgen:::generateNoise(len = samplingRate, rolloffNoise = -12,
  samplingRate = samplingRate, filterNoise = filterNoise)
# plot (filterNoise, type = 'l')
# playme(noise, samplingRate = samplingRate)

# low-frequency, wind-like noise
filterNoise = soundgen:::getSpectralEnvelope(
  nr = windowLength_points / 2, nc = 1, rolloffLip = 0,
  samplingRate = samplingRate, formants = list('f1' = data.frame(
    time = 0, freq = 150, amp = 30, width = 90)))
noise = soundgen:::generateNoise(len = samplingRate, rolloffNoise = -12,
  samplingRate = samplingRate, filterNoise = filterNoise)
# }