soundgen (version 1.8.2)

addAM: Add amplitude modulation

Description

Adds sinusidal or logistic amplitude modulation to a sound. This produces additional harmonics in the spectrum at <U+00B1>am_freq around each original harmonic and makes the sound rough. The optimal frequency for creating a perception of roughness is ~70 Hz (Fastl & Zwicker "Psychoacoustics"). Sinusoidal AM creates a single pair of new harmonics, while non-sinusoidal AM creates more extra harmonics (see examples).

Usage

addAM(
  x,
  samplingRate = NULL,
  amDep = 25,
  amFreq = 30,
  amType = c("logistic", "sine")[1],
  amShape = 0,
  invalidArgAction = c("adjust", "abort", "ignore")[1],
  plot = FALSE,
  play = FALSE,
  checkFormat = TRUE
)

Arguments

x

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

samplingRate

sampling frequency, Hz

amDep

amplitude modulation (AM) depth, %. 0: no change; 100: AM with amplitude range equal to the dynamic range of the sound (anchor format)

amFreq

AM frequency, Hz (anchor format)

amType

"sine" = sinusoidal, "logistic" = logistic (default)

amShape

ignore if amType = "sine", otherwise determines the shape of non-sinusoidal AM: 0 = ~sine, -1 = notches, +1 = clicks (anchor format)

invalidArgAction

what to do if an argument is invalid or outside the range in permittedValues: 'adjust' = reset to default value, 'abort' = stop execution, 'ignore' = throw a warning and continue (may crash)

plot

if TRUE, plots the amplitude modulation

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

checkFormat

only FALSE when called internally by soundgen()

Examples

# NOT RUN {
sound1 = soundgen(pitch = c(200, 300), addSilence = 0)
s1 = addAM(sound1, 16000, amDep = c(0, 50, 0), amFreq = 75, plot = TRUE)
# playme(s1)
# }
# NOT RUN {
# Parameters can be specified as in the soundgen() function, eg:
s2 = addAM(sound1, 16000,
         amDep = list(time = c(0, 50, 52, 200, 201, 300),
                      value = c(0, 0, 35, 25, 0, 0)),
         plot = TRUE, play = TRUE)

# Sinusoidal AM produces exactly 2 extra harmonics at <U+00B1>am_freq around each f0
harmonic:
s3 = addAM(sound2, 16000, amDep = 30, amFreq = c(50, 80), amType = 'sine',
           plot = TRUE, play = TRUE)
spectrogram(s3, 16000, windowLength = 150, ylim = c(0, 2))

# Non-sinusoidal AM produces multiple new harmonics, which can resemble
subharmonics...
s4 = addAM(sound2, 16000, amDep = 70, amFreq = 50, amShape = -1,
           plot = TRUE, play = TRUE)
spectrogram(s4, 16000, windowLength = 150, ylim = c(0, 2))

# ...but more often look like sidebands
sound3 = soundgen(sylLen = 600, pitch = c(800, 1300, 1100), addSilence = 0)
s5 = addAM(sound3, 16000, amDep = c(0, 30, 100, 40, 0),
           amFreq = 105, amShape = -.3,
           plot = TRUE, play = TRUE)
spectrogram(s5, 16000, ylim = c(0, 5))

# Feel free to add AM stochastically:
s6 = addAM(sound2, 16000,
           amDep = rnorm(10, 40, 20), amFreq = rnorm(20, 70, 20),
           plot = TRUE, play = TRUE)
spectrogram(s6, 16000, windowLength = 150, ylim = c(0, 2))

# If am_freq is locked to an integer ratio of f0, we can get subharmonics
# For ex., here is with pitch 400-600-400 Hz (soundgen interpolates pitch
# on a log scale and am_freq on a linear scale, so we align them by extracting
# a long contour on a log scale for both)
con = getSmoothContour(anchors = c(400, 600, 400),
                       len = 20, thisIsPitch = TRUE)
s = soundgen(sylLen = 1500, pitch = con, amFreq = con/3, amDep = 30,
             plot = TRUE, play = TRUE, ylim = c(0, 3))
# }