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 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,
  stereo = c("left", "right", "average", "both")[1],
  killDC = FALSE,
  normalize = TRUE,
  windowDC = 200,
  summaryFun = "mean",
  reportEvery = NULL,
  cores = 1,
  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, 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, %
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, 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)
cores	number of cores for parallel processing
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)
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

Returns 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 = '~/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

## End(Not run)

soundgen documentation built on Sept. 12, 2024, 6:29 a.m.