getSurprisal: Get surprisal

View source: R/surprisal.R

getSurprisalR Documentation

Get surprisal


Tracks the (un)predictability of spectral changes in a sound over time, returning a continuous contour of "surprisal". This is an attempt to track auditory salience over time - that is, to identify parts of a sound that are likely to involuntarily attract the listeners' attention. The functions returns surprisal proper ('$surprisal') and its product with increases in loudness ('$surprisalLoudness'). Because getSurprisal() is slow and experimental, it is not called by analyze().


  samplingRate = NULL,
  scale = NULL,
  from = NULL,
  to = NULL,
  step = 20,
  winSurp = 2000,
  yScale = c("bark", "mel", "log")[1],
  nFilters = 64,
  dynamicRange = 80,
  minFreq = 20,
  maxFreq = samplingRate/2,
  summaryFun = "mean",
  reportEvery = NULL,
  cores = 1,
  plot = TRUE,
  savePlots = NULL,
  osc = c("none", "linear", "dB")[2],
  heights = c(3, 1),
  ylim = NULL,
  contrast = 0.2,
  brightness = 0,
  maxPoints = c(1e+05, 5e+05),
  padWithSilence = TRUE,
  colorTheme = c("bw", "seewave", "heat.colors", "...")[1],
  extraContour = NULL,
  xlab = NULL,
  ylab = NULL,
  xaxp = NULL,
  mar = c(5.1, 4.1, 4.1, 2),
  main = NULL,
  grid = NULL,
  width = 900,
  height = 500,
  units = "px",
  res = NA,



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


sampling rate of x (only needed if x is a numeric vector)


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

from, to

if NULL (default), analyzes the whole sound, otherwise (s)


step, ms (determines time resolution). step = NULL means no downsampling at all (ncol of output = length of input audio)


surprisal analysis window, ms


scale of the frequency axis: 'linear' = linear, 'log' = logarithmic (musical), 'bark' = bark with hz2bark, 'mel' = mel with hz2mel, 'ERB' = Equivalent Rectangular Bandwidths with HzToERB


the number of filters (determines frequency resolution)


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

minFreq, maxFreq

the range of frequencies to analyze


functions used to summarize each acoustic characteristic, eg "c('mean', 'sd')"; user-defined functions are fine (see examples); NAs are omitted automatically for mean/median/sd/min/max/range/sum, otherwise take care of NAs yourself


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


number of cores for parallel processing


if TRUE, plots the auditory spectrogram and the suprisalLoudness contour


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


"none" = no oscillogram; "linear" = on the original scale; "dB" = in decibels


a vector of length two specifying the relative height of the spectrogram and the oscillogram (including time axes labels)


frequency range to plot, kHz (defaults to 0 to Nyquist frequency). NB: still in kHz, even if yScale = bark, mel, or ERB


spectrum is exponentiated by contrast (any real number, recommended -1 to +1). Contrast >0 increases sharpness, <0 decreases sharpness


how much to "lighten" the image (>0 = lighter, <0 = darker)


the maximum number of "pixels" in the oscillogram (if any) and spectrogram; good for quickly plotting long audio files; defaults to c(1e5, 5e5)


if TRUE, pads the sound with just enough silence to resolve the edges properly (only the original region is plotted, so the apparent duration doesn't change)


black and white ('bw'), as in seewave package ('seewave'), or any palette from palette such as 'heat.colors', 'cm.colors', etc


a vector of arbitrary length scaled in Hz (regardless of yScale!) that will be plotted over the spectrogram (eg pitch contour); can also be a list with extra graphical parameters such as lwd, col, etc. (see examples)

xlab, ylab, main, mar, xaxp

graphical parameters for plotting


if numeric, adds n = grid dotted lines per kHz

width, height, units, res

graphical parameters for saving plots passed to png


other graphical parameters


Algorithm: we start with an auditory spectrogram produced by applying a bank of bandpass filters to the signal, by default with central frequencies equally spaced on the bark scale (see audSpectrogram). For each frequency channel, a sliding window is analyzed to compare the actually observed final value with its expected value. There are many ways to extrapolate / predict time series and thus perform this comparison. Here, we calculate the autocorrelation function of the window without the final point, find its peak (i.e., the delay that produces the highest autocorrelation), calculate autocorrelation of the window with the final point at this "optimal" delay, and compare these two correlations. In effect, we estimate how far the final point in our window deviates from the dominant oscillation frequency or "fundamental frequency" of the time series, which in this case represents the changes in amplitude in the same frequency channel over time. The resulting per-channel surprisal contours are aggregated by taking their mean weighted by the average amplitude of each frequency channel across the analysis window. Because increases in loudness are known to be important predictors of auditory salience, loudness per frame is also returned, as well as the square root of the product of its derivative and surprisal.


Returns a list with $detailed per-frame and $summary per-file results (see analyze for more information). Three measures are reported: loudness (in sone, as per getLoudness), the first derivative of loudness with respect to time (dLoudness), surprisal (non-negative), and suprisalLoudness (geometric mean of surprisal and dLoudness, treating negative values of dLoudnessas zero).


# A quick example
s = soundgen(nSyl = 2, sylLen = 50, pauseLen = 25, addSilence = 15)
surp = getSurprisal(s, samplingRate = 16000)

## Not run: 
# A more meaningful example
sound = soundgen(nSyl = 5, sylLen = 150,
  pauseLen = c(50, 50, 50, 130), pitch = c(200, 150),
  noise = list(time = c(-300, 200), value = -20), plot = TRUE)
# playme(sound)
surp = getSurprisal(sound, samplingRate = 16000, yScale = 'bark')

# NB: surprisalLoudness contour is also log-transformed if yScale = 'log',
# so zeros become NAs
surp = getSurprisal(sound, samplingRate = 16000, yScale = 'log')

# add bells and whistles
surp = getSurprisal(sound, samplingRate = 16000,
  yScale = 'mel',
  osc = 'dB',  # plot oscillogram in dB
  heights = c(2, 1),  # spectro/osc height ratio
  brightness = -.1,  # reduce brightness
  colorTheme = 'heat.colors',  # pick color theme
  cex.lab = .75, cex.axis = .75,  # text size and other base graphics pars
  ylim = c(0, 5),  # always in kHz
  main = 'Audiogram with surprisal contour' # title
  # + axis labels, etc

surp = getSurprisal('~/Downloads/temp/', savePlots = '~/Downloads/temp/surp')

## End(Not run)

soundgen documentation built on Aug. 14, 2022, 5:05 p.m.