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Measure amplitude envelope correlation

Source: R/envelope_correlation.R
envelope_correlation.Rd

envelope_correlation() measures amplitude envelope correlation of sounds referenced in an extended selection table. Amplitude envelope correlation measures the similarity of two sounds in the time domain.

Usage

envelope_correlation(
  X,
  cores = getOption("mc.cores", 1),
  pb = getOption("pb", TRUE),
  cor.method = c("pearson", "spearman", "kendall"),
  env.smooth = getOption("env.smooth", 200),
  hop.size = getOption("hop.size", 11.6),
  wl = getOption("wl", NULL),
  ovlp = getOption("ovlp", 70),
  path = getOption("sound.files.path", ".")
)

Arguments

X

The output of set_reference_sounds(), an object of class data.frame, selection_table, or extended_selection_table (the last 2 classes are created by warbleR::selection_table() from the warbleR package) with the test sound files' annotations. Must contain the following columns: 1) sound.files: name of the .wav files, 2) selec: unique selection identifier (within a sound file), 3) start: start time and 4) end: end time of selections, 5) bottom.freq: low frequency for bandpass, 6) top.freq: high frequency for bandpass, 7) sound.id: ID of sounds used to identify counterparts across distances, and 8) reference: identity of sounds to be used as reference for each test sound (row). See set_reference_sounds() for more details on the structure of X.

cores

Numeric vector of length 1. Controls whether parallel computing is applied by specifying the number of cores to be used. Default 1 (i.e. no parallel computing). Can be set globally for the current R session via the "mc.cores" option (see options()).

pb

Logical argument to control if progress bar is shown. Default TRUE. Can be set globally for the current R session via the "pb" option (see options()).

cor.method

Character string indicating the correlation coefficient to be applied ("pearson", "spearman", or "kendall", see stats::cor()).

env.smooth

Numeric vector of length 1 to determine the length of the sliding window used for a sum smooth for amplitude envelope calculation (used internally by seewave::env()). Can be set globally for the current R session via the "env.smooth" option (see options()).

hop.size

Numeric vector of length 1 specifying the time window duration (in ms). Default 11.6 ms, which is equivalent to 512 wl for a 44.1 kHz sampling rate. Ignored if wl is supplied. Can be set globally for the current R session via the "hop.size" option (see options()).

wl

A vector with a single even integer number specifying the window length of the spectrogram. Default NULL. If supplied, hop.size is ignored. Odd integers will be rounded up to the nearest even number. Can be set globally for the current R session via the "wl" option (see options()).

ovlp

Numeric vector of length 1 specifying the percentage of overlap between two consecutive windows, as in seewave::spectro(). Default 70. Can be set globally for the current R session via the "ovlp" option (see options()).

path

Character string containing the directory path where the sound files are found. Only needed when X is not an extended selection table. If not supplied the current working directory is used. Can be set globally for the current R session via the "sound.files.path" option (see options()).

Value

Object X with an additional column, envelope.correlation, containing the computed envelope correlation coefficients.

Details

The function measures the envelope correlation coefficients of sounds in which a reference playback has been re-recorded at increasing distances. Values close to 1 mean very similar amplitude envelopes (i.e. little degradation has occurred). If envelopes have different lengths (which means sounds have different lengths), cross-correlation is used and the maximum correlation coefficient is returned. Cross-correlation is achieved by sliding the shortest sound along the largest one and computing the correlation at each step. The sound.id column must be used to indicate that the function should only compare sounds belonging to the same category (e.g. song-types). The function compares each sound to the corresponding reference sound within the supplied frequency range (e.g. bandpass) of the reference sound (bottom.freq and top.freq columns in X). Two methods for computing envelope correlation are provided (see the method argument). Use blur_ratio() to create envelope graphs.

References

Araya-Salas, M., Grabarczyk, E. E., Quiroz-Oliva, M., Garcia-Rodriguez, A., & Rico-Guevara, A. (2025). Quantifying degradation in animal acoustic signals with the R package baRulho. Methods in Ecology and Evolution, 00, 1-12. https://doi.org/10.1111/2041-210X.14481

Apol, C.A., Sturdy, C.B. & Proppe, D.S. (2017). Seasonal variability in habitat structure may have shaped acoustic signals and repertoires in the black-capped and boreal chickadees. Evol Ecol. 32:57-74.

See also

blur_ratio() and spectrum_blur_ratio().

Other quantify degradation: blur_ratio(), detection_distance(), plot_blur_ratio(), plot_degradation(), set_reference_sounds(), signal_to_noise_ratio(), spcc(), spectrum_blur_ratio(), spectrum_correlation(), tail_to_signal_ratio()

Author

Marcelo Araya-Salas (marcelo.araya@ucr.ac.cr)

Examples

{
  # load example data
  data("test_sounds_est")

  # add reference to X
  X <- set_reference_sounds(X = test_sounds_est)

  envelope_correlation(X = X)

  # method 2
  # add reference to X
  X <- set_reference_sounds(X = test_sounds_est, method = 2)
  envelope_correlation(X = X)
}
#> Object of class 'extended_selection_table'
#> * The output of the following call:
#> `[.extended_selection_table`(X = test_sounds_est, i = order(test_sounds_est$sound.id,  test_sounds_est$transect, decreasing = FALSE))
#> 
#> Contains: 
#> *  A selection table data frame with 25 row(s) and 11 columns:
#>      sound.files       selec   start      end   bottom.freq   top.freq
#> ---  ---------------  ------  ------  -------  ------------  ---------
#> 8    10m_closed.wav        1    0.05   0.2000        1.3333     2.6667
#> 23   30m_closed.wav        1    0.05   0.2000        1.3333     2.6667
#> 13   10m_open.wav          1    0.05   0.2000        1.3333     2.6667
#> 18   1m_open.wav           1    0.05   0.2000        1.3333     2.6667
#> 28   30m_open.wav          1    0.05   0.2000        1.3333     2.6667
#> 11   10m_closed.wav        4    1.80   2.0001        0.4220     1.2230
#> ... 5 more column(s) (sound.id, transect, distance, reference, envelope.correlation)
#>  and 19 more row(s)
#> 
#> * 5 wave object(s) (as attributes): 
#> 10m_closed.wav, 10m_open.wav, 1m_open.wav, 30m_closed.wav, 30m_open.wav
#> 
#> * A data frame (check.results) with 25 rows generated by check_sels() (as an attribute)
#> 
#> Additional information:
#> * The selection table was created by song (see description in '?selection_table')
#> * 1 sampling rate(s) (in kHz): 22.05
#> * 1 bit depth(s): 16
#> * Created by warbleR < 1.1.21