addAM | R Documentation |

Adds sinusoidal or logistic amplitude modulation to a sound. This produces additional harmonics in the spectrum at ±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).

```
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,
saveAudio = NULL,
reportEvery = NULL,
cores = 1
)
```

`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 |

`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 |

`plot` |
if TRUE, plots the amplitude modulation |

`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 |

```
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 ±am_freq
# around each f0 harmonic:
s3 = addAM(sound1, 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(sound1, 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(sound1, 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))
# Process all files in a folder and save the modified audio
addAM('~/Downloads/temp', saveAudio = '~/Downloads/temp/AM',
amFreq = 70, amDep = c(0, 50))
## End(Not run)
```

soundgen documentation built on Sept. 29, 2023, 5:09 p.m.

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