getRoughness: Calculate prop or fluctuation

In soundgen: Sound Synthesis and Acoustic Analysis

Calculate prop or fluctuation

Description

Calculates psychoacoustic roughness or slow fluctuation strength as the proportion of a modulation spectrum that falls within a specified range of temporal modulation frequencies - both as a single total value and per frequency band. Roughness or fluctuation can be calculated either as the simple proportion of the spectrum within modRange, or as a weighted version using a lognormal weighting function centered at modMean with spread modSD. Recommended weighting function for measuring roughness: modMean = 100, modSD = 8 (100 Hz ± 8 semitones); for measuring low-frequency fluctuation: modMean = 4, modSD = 12 (4 Hz ± 12 semitones). Because the result is a proportion (numerator and denominator are summed over the same modulation-frequency columns), positive and negative temporal modulation frequencies do not need to be folded: any mirroring cancels out.

Usage

getRoughness(m, modRange = NULL, modMean = 100, modSD = 8, plot = FALSE)

Arguments

m	numeric matrix of non-negative values with column names giving temporal modulation frequencies (Hz). Row names, if present, are used as the frequency-band labels in the output.
modRange, modMean, modSD	like "roughRange, roughMean, roughSD" or "fluctRange, fluctMean, fluctSD" in modulationSpectrum()
plot	if TRUE, plots a one-sided AM spectrum with the selected frequency range and weighting function

Value

A list with two components:

• prop: the proportion of MS in the target range of modulation frequencies, in percent (NA if no valid modRange or weighting parameters, empty input, or no energy in the spectrum).

• details: a data.frame with one row per frequency band and columns freq (band label), prop (band-wise contribution to total proportion, %), and amp (mean band amplitude, normalized to the maximum band).

See Also

modulationSpectrum

Examples

s = soundgen(jitterDep = 2, amFreq = 80, amDep = 70, addSilence = 0)
m = modulationSpectrum(s, 16000, amRes = NULL, plot = FALSE)$detailed$original

## Ex. 1: simple proportion within modRange
r = soundgen:::getRoughness(m, modRange = c(30, Inf), plot = TRUE)
r = soundgen:::getRoughness(m, modRange = c(30, 150), plot = TRUE)
plot(r$details$freq, r$details$prop, type = 'b')
r$prop == sum(r$details$prop)

## Ex. 2: lognormal weighting function instead of modRange
# narrow
soundgen:::getRoughness(m, modRange = NULL, modMean = 75,
  modSD = 3, plot = TRUE)
# broad
soundgen:::getRoughness(m, modRange = NULL, modMean = 75,
  modSD = 10, plot = TRUE)
# truncated at modRange
soundgen:::getRoughness(m, modRange = c(30, 200), modMean = 75,
  modSD = 10, plot = TRUE)
# NB: a very large modSD means we essentially revert to a simple proportion

## Ex. 3: measure low-frequency AM fluctuation instead of prop
# (just use a different weighting function)
s2 = sinpi(2*440*(1:16000)/16000) * (1 - cospi(2*5*(1:16000)/16000))
osc(s2, 16000)
m2 = modulationSpectrum(s2, 16000, amRes = NULL, plot = FALSE)$detailed$original
fl = soundgen:::getRoughness(m2, modRange = c(0.25, 30), modMean = 4,
  modSD = 12, plot = TRUE)
fl$prop  # in this case, a measure of slow fluctuation

soundgen documentation built on Sept. 20, 2026, 5:07 p.m.