soundgen (version 3.0.0)

spectrum: 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,
  ...
)

Value

A dataframe with two columns: freq (frequency in kHz) and

ampl (amplitude, in units determined by yScale).

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

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)

if (FALSE) {
# Process all .wav files in a folder
spectrum('~/Downloads/temp', savePlots = TRUE, yScale = 'dB')
}