soundgen (version 2.4.0)

getRMS: RMS amplitude

Description

Calculates root mean square (RMS) amplitude in overlapping windows, providing an envelope of RMS amplitude - a measure of sound intensity. Longer windows provide smoother, more robust estimates; shorter windows and more overlap improve temporal resolution, but they also increase processing time and make the contour less smooth.

Usage

getRMS(
  x,
  samplingRate = NULL,
  scale = NULL,
  from = NULL,
  to = NULL,
  windowLength = 50,
  step = NULL,
  overlap = 70,
  killDC = FALSE,
  normalize = TRUE,
  windowDC = 200,
  summaryFun = "mean",
  reportEvery = NULL,
  plot = FALSE,
  savePlots = NULL,
  main = NULL,
  xlab = "",
  ylab = "",
  type = "b",
  col = "green",
  lwd = 2,
  width = 900,
  height = 500,
  units = "px",
  res = NA,
  ...
)

Arguments

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 x (only needed if x is a numeric vector)

scale

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

from

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

to

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

windowLength

length of FFT window, ms

step

you can override overlap by specifying FFT step, ms (NB: because digital audio is sampled at discrete time intervals of 1/samplingRate, the actual step and thus the time stamps of STFT frames may be slightly different, eg 24.98866 instead of 25.0 ms)

overlap

overlap between successive FFT frames, %

killDC

if TRUE, removed DC offset (see also flatEnv)

normalize

if TRUE, the RMS amplitude is returned as proportion of the maximum possible amplitude as given by scale

windowDC

the window for calculating DC offset, ms

summaryFun

functions used to summarize each acoustic characteristic; see analyze

reportEvery

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

plot

if TRUE, plot a contour of RMS amplitude

savePlots

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

main

graphical parameters for plotting

xlab, ylab

general graphical parameters

type, col, lwd

graphical parameters pertaining to the RMS envelope

width

graphical parameters for saving plots passed to png

height

graphical parameters for saving plots passed to png

units

graphical parameters for saving plots passed to png

res

graphical parameters for saving plots passed to png

...

other graphical parameters

Value

Returns a list containing:

• $summary: a dataframe with summary measures, one row per sound

Details

Note that you can also get similar estimates per frame from analyze on a normalized scale of 0 to 1, but getRMS is much faster, operates on the original scale, and plots the amplitude contour. If you need RMS for the entire sound instead of per frame, you can simply calculate it as sqrt(mean(x^2)), where x is your waveform. Having RMS estimates per frame gives more flexibility: RMS per sound can be calculated as the mean / median / max of RMS values per frame.

See Also

analyze getLoudness

Examples

# NOT RUN {
s = soundgen() + .25  # with added DC offset
osc(s)
r = getRMS(s, samplingRate = 16000,
  windowLength = 40, overlap = 50, killDC = TRUE,
  plot = TRUE, type = 'l', lty = 2, main = 'RMS envelope')
# short window = jagged envelope
r = getRMS(s, samplingRate = 16000,
  windowLength = 5, overlap = 0, killDC = TRUE,
  plot = TRUE, col = 'blue', pch = 13, main = 'RMS envelope')
# }
# NOT RUN {
r = getRMS('~/Downloads/temp', savePlots = '~/Downloads/temp/plots')
r$summary

# Compare:
analyze('~/Downloads/temp', pitchMethods = NULL,
        plot = FALSE)$ampl_mean
# (per STFT frame, but should be very similar)

User-defined summary functions:
ran = function(x) diff(range(x))
meanSD = function(x) {
  paste0('mean = ', round(mean(x), 2), '; sd = ', round(sd(x), 2))
}
getRMS('~/Downloads/temp', summaryFun = c('mean', 'ran', 'meanSD'))$summary
# }