getRMS: RMS amplitude

In soundgen: Sound Synthesis and Acoustic Analysis

RMS amplitude

Description

Calculates root mean square (RMS) amplitude in overlapping windows, providing an envelope 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,
  stereo = c("left", "right", "average", "both"),
  killDC = FALSE,
  normalize = TRUE,
  windowDC = 200,
  summaryFun = "mean",
  reportEvery = NULL,
  cores = 1,
  plot = FALSE,
  savePlots = FALSE,
  embed = FALSE,
  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 to normalize the input vector (only needed if x is a numeric vector)
from, to	if NULL (default), analyzes the whole sound, otherwise from...to (s)
windowLength	length of analysis window, ms (longer windows = more smoothing)
step	step between successive windows, ms; if provided, overrides overlap; 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 - e.g., 24.98866 instead of 25.0 ms
overlap	overlap between successive windows, %
stereo	'left' = only left channel, 'right' = only right channel, 'average' = take the mean of the two channels, 'both' = return RMS for both channels separately
killDC	if TRUE, removes 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, 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
reportEvery	when processing multiple inputs, report estimated time left every reportEvery iterations (NULL = default, NA = don't report); see reportTime
cores	number of cores for parallel processing
plot	if TRUE, plot a contour of RMS amplitude
savePlots	if TRUE, creates a subdirectory in the input directory (if input is a file or folder) or in the working directory (if input is a vector etc), named after the function (eg "spectrogram/"). All plots and audio files (if any) are saved in this new directory. If there are multiple inputs, an html notebook is also created for easy viewing and listening
embed	if TRUE and savePlots is set and there are multiple inputs, all saved images and audio (if any) are embedded in the exported html notebook for easy sharing; if FALSE, the html file links to separate images and audio files (but separate files are still saved). NB: for this to work, package "base64enc" must be installed
xlab, ylab, main	general graphical parameters
type, col, lwd	graphical parameters pertaining to the RMS envelope
width, height, units, res	graphical parameters for saving plots passed to png
...	other graphical parameters

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.

Value

A list containing:

$detailed:

a list of RMS amplitudes per frame for each sound, on the scale of input; names give time stamps for the center of each frame, in ms.

$summary:

a dataframe with summary measures, one row per sound

See Also

analyze getLoudness

Examples

s = soundgen() + .25  # with added DC offset
# osc(s)
r = getRMS(s, samplingRate = 16000, from = .05,
  windowLength = 40, overlap = 50, killDC = TRUE,
  plot = TRUE, type = 'l', lty = 2, main = 'RMS envelope')
r

# short window = jagged envelope
r = getRMS(s, samplingRate = 16000,
  windowLength = 5, overlap = 0, killDC = TRUE,
  plot = TRUE, col = 'blue', pch = 13, main = 'RMS envelope')

 # stereo
 wave_stereo = tuneR::Wave(
   left = runif(1000, -1, 1) * 16000,
   right = runif(1000, -1, 1) / 3 * 16000,
   bit = 16, samp.rate = 4000)
 getRMS(wave_stereo)$summary
 getRMS(wave_stereo, stereo = 'right')$summary
 getRMS(wave_stereo, stereo = 'average')$summary
 getRMS(wave_stereo, from = .05,
   stereo = 'both', plot = TRUE)$summary

## Not run: 
r = getRMS('~/Downloads/temp', savePlots = TRUE)
r$summary

# Compare:
analyze('~/Downloads/temp', pitchMethods = NULL,
        plot = FALSE)$summary$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

## End(Not run)

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