spectrum: Spectrum

In soundgen: Sound Synthesis and Acoustic Analysis

Spectrum

Description

spectrum computes the frequency spectrum of a sound using the Fast Fourier Transform (FFT). For a smoother appearance and faster processing of long sounds, meanSpectrum computes the time-averaged spectrum of successive windows. See the "spec" and "meanspec" functions in the seewave package for more plotting options. NB: soundgen::spectrum() masks stats::spectrum().

Usage

spectrum(
  x,
  samplingRate = NULL,
  from = NULL,
  to = NULL,
  zp = NULL,
  yScale = c("linear", "power", "dB", "max0"),
  plot = TRUE,
  savePlots = FALSE,
  embed = FALSE,
  main = NULL,
  xlab = NULL,
  ylab = NULL,
  width = 900,
  height = 500,
  units = "px",
  res = NA,
  reportEvery = NULL,
  cores = 1,
  ...
)

meanSpectrum(
  x,
  samplingRate = NULL,
  from = NULL,
  to = NULL,
  windowLength = 50,
  step = windowLength/2,
  overlap = NULL,
  wn = "gaussian",
  zp = NULL,
  reportEvery = NULL,
  cores = 1,
  plot = TRUE,
  yScale = c("linear", "power", "dB", "max0"),
  savePlots = FALSE,
  embed = FALSE,
  main = NULL,
  xlab = NULL,
  ylab = NULL,
  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)
from, to	if NULL (default), analyzes the whole sound, otherwise from...to (s)
zp	window length after zero padding, samples. No padding is performed if zp < analysis window length in samples. If NULL, the signal is padded to a good number for speeding up the FFT
yScale	scale of the y-axis: "linear" for linear amplitude, "power" for power spectrum, "dB" for decibels (20*log10), "max0" for dB with the maximum set to 0 dB
plot	if TRUE, plots the spectrum
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	graphical parameters for plotting
width, height, units, res	graphical parameters for saving plots passed to png
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
...	other graphical parameters passed to plot()
windowLength	length of the analysis window, ms
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, %
wn	window type accepted by winFun: character string or function

Value

A dataframe with two columns: freq (frequency in kHz) and ampl (amplitude, in units determined by yScale).

Examples

# 500 Hz tone
sound = cos(2 * pi * 500 * (1:4000) / 16000) + rnorm(4000, 0, .05)

# Spectrum on linear scale
spectrum(sound, samplingRate = 16000, yScale = 'linear')
meanSpectrum(sound, samplingRate = 16000, yScale = 'linear')

# dB scale with custom labels
spectrum(sound, samplingRate = 16000, yScale = 'dB', col = 'blue',
         xlab = 'Frequency (kHz)', ylab = 'Amplitude (dB)')

# max0 scale with custom y-limits and extra graphical pars
meanSpectrum(sound, samplingRate = 16000, yScale = 'max0',
  xlim = c(0, 2), ylim = c(-50, 5), lty = 2, lwd = 3, col = 'blue')

# Return data without plotting
ms = meanSpectrum(sound, samplingRate = 16000, plot = FALSE)
head(ms)

# If windowLength is longer than the sound, meanSpectrum() = spectrum()
spectrum(sound, 16000)
meanSpectrum(sound, 16000, windowLength = 5000)

## Not run: 
# Process all .wav files in a folder
spectrum('~/Downloads/temp', savePlots = TRUE, yScale = 'dB')

## End(Not run)

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