tail_to_signal_ratio {baRulho}

Measure reverberations as tail-to-signal ratio

Description

tail_to_signal_ratio measures reverberations as tail-to-signal ratio of sounds referenced in an extended selection table.

Usage

tail_to_signal_ratio(
  X,
  mar,
  cores = getOption("mc.cores", 1),
  pb = getOption("pb", TRUE),
  tsr.formula = 1,
  bp = "freq.range",
  hop.size = getOption("hop.size", 1),
  wl = getOption("wl", NULL),
  ovlp = getOption("ovlp", 0),
  path = getOption("sound.files.path", ".")
)

Arguments

X

Object of class 'data.frame', 'selection_table' or 'extended_selection_table' (the last 2 classes are created by the function selection_table from the warbleR package) with the reference to the test sounds . 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 and 6) "top.freq": high frequency for bandpass.

mar

numeric vector of length 1. Specifies the margins adjacent to end of the sound over which to measure tail power.

cores

Numeric vector of length 1. Controls whether parallel computing is applied by specifying the number of cores to be used. Default is 1 (i.e. no parallel computing).

pb

Logical argument to control if progress bar is shown. Default is TRUE.

tsr.formula

Integer vector of length 1. Determine the formula to be used to calculate the tail-to-signal ratio (S = signal, T = tail, N = background noise):

• 1: ratio of T amplitude envelope quadratic mean to S amplitude envelope quadratic mean (rms(env(T))/rms(env(S))) as described by Dabelsteen et al. (1993).

• 2: ratio of T amplitude envelope quadratic mean to N amplitude envelope quadratic mean (rms(env(T))/rms(env(N))). N is measure in the margin right before the sound. So tsr.formula 2 actually measures tail-to-noise ratio.

bp

Numeric vector of length 2 giving the lower and upper limits of a frequency bandpass filter (in kHz). Alternatively, when set to 'freq.range' (default), the function will use the 'bottom.freq' and 'top.freq' for each sound as the bandpass range.

hop.size

A numeric vector of length 1 specifying the time window duration (in ms). Default is 1 ms, which is equivalent to ~45 wl for a 44.1 kHz sampling rate. Ignored if 'wl' is supplied.

wl

A numeric vector of length 1 specifying the window length of the spectrogram, default is NULL. Ignored if bp = NULL. If supplied, 'hop.size' is ignored. Note that lower values will increase time resolution, which is more important for amplitude calculations.

ovlp

Numeric vector of length 1 specifying the percentage of overlap between two consecutive windows, as in spectro. Default is 0. Only used for bandpass filtering.

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.

Details

Tail-to-signal ratio (TSR) measures the ratio of power in the tail of reverberations to that in the test sound. A general margin in which reverberation tail will be measured must be specified. The function will measure TSR within the supplied frequency range (e.g. bandpass) of the reference sound ('bottom.freq' and 'top.freq' columns in 'X'). Two methods for computing reverberations are provided (see 'tsr.formula' argument). Note that 'tsr.formula' 2 is not equivalent to the original description of TSR in Dabelsteen et al. (1993) and is better referred to as tail-to-noise ratio. Tail-to-signal ratio values are typically negative as signals tend to have higher power than that in the reverberating tail. TSR can be ~0 when both tail and signal have very low amplitude.

Value

Object 'X' with an additional column, 'tail.to.signal.ratio', with the tail-to-signal ratio values (in dB).

Author(s)

Marcelo Araya-Salas ([e-mail])

References

Araya-Salas M., E. Grabarczyk, M. Quiroz-Oliva, A. Garcia-Rodriguez, A. Rico-Guevara. (2023), baRulho: an R package to quantify degradation in animal acoustic signals .bioRxiv 2023.11.22.568305.

Darden, SK, Pedersen SB, Larsen ON, & Dabelsteen T. (2008). Sound transmission at ground level in a short-grass prairie habitat and its implications for long-range communication in the swift fox *Vulpes velox*. The Journal of the Acoustical Society of America, 124(2), 758-766.

Mathevon, N., Dabelsteen, T., & Blumenrath, S. H. (2005). Are high perches in the blackcap Sylvia atricapilla song or listening posts? A sound transmission study. The Journal of the Acoustical Society of America, 117(1), 442-449.

See Also

excess_attenuation

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

Examples

{
  # load example data

  data("test_sounds_est")

  # set global options
  options(pb = FALSE)

  # using margin for noise of 0.01
  tsr <- tail_to_signal_ratio(X = test_sounds_est, mar = 0.01)

  # use tsr.formula 2 which is equivalent to tail-to-noise ratio
  tsr <- tail_to_signal_ratio(X = test_sounds_est, mar = 0.01, tsr.formula = 2)
}