excess_attenuation measures excess attenuation in signals referenced in an extended selection table.
excess_attenuation(X, parallel = 1, pb = TRUE, method = 1,
bp = NULL, output = "est", hop.size = 1, wl = NULL, ovlp = 70)object of class 'extended_selection_table' created by the function selection_table from the warbleR package. The data frame must include the following additional columns: 'distance', 'signal.type', 'bottom.freq' and 'top.freq'.
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).
Logical argument to control if progress bar is shown. Default is TRUE.
Numeric vector of length 1 to indicate the 'experimental design' for measuring excess attenuation. Two methods are available:
1: compare all signals with their counterpart that was recorded at the closest distance to source (e.g. compare a signal recorded at 5m, 10m and 15m with its counterpart recorded at 1m). This is the default method.
2: compare all signals with their counterpart recorded at the distance immediately before (e.g. a signal recorded at 10m compared with the same signal recorded at 5m, then signal recorded at 15m compared with same signal recorded at 10m and so on).
Numeric vector of length 2 giving the lower and upper limits of a frequency bandpass filter (in kHz). Default is NULL.
Character vector of length 1 to determine if an extended selection table ('est', default) or a data frame ('data.frame').
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.
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 ratio calculations.
Numeric vector of length 1 specifying the percent overlap between two
consecutive windows, as in spectro. Only used when plotting. Default is 70. Only used for bandpass filtering.
Extended selection table similar to input data, but also includes a new column (excess.attenuation) with the excess attenuation values.
Excess attenuation is the amplitude loss of a sound in excess due to spherical spreading. With every doubling of distance, sounds attenuate with a 6 dB loss of amplitude (Morton, 1975; Marten & Marler, 1977). Any additional loss of amplitude results in excess attenuation, or energy loss in excess of that expected to occur with distance via spherical spreading, due to atmospheric conditions or habitat (Wiley & Richards, 1978). Low values indicate little signal attenuation. The goal of the function is to measure the excess attenuation on signals in which a reference playback has been re-recorded at increasing distances. The 'signal.type' column must be used to indicate which signals belonging to the same category (e.g. song-types). The function will then compare each signal type to the corresponding reference signal the supplied frequency range (e.g. bandpass) of the reference signal ('bottom.freq' and 'top.freq' columns in 'X'). Two methods for calculating excess attenuation are provided (see 'method' argument).
Araya-Salas, M. (2020),=. baRulho: baRulho: quantifying habitat-induced degradation of (animal) acoustic signals in R. R package version 1.0.0
Marten, K., & Marler, P. (1977). Sound transmission and its significance for animal vocalization. Behavioral Ecology and Sociobiology, 2(3), 271-290.
Morton, E. S. (1975). Ecological sources of selection on avian sounds. The American Naturalist, 109(965), 17-34.
# NOT RUN {
{
# load example data
data("playback_est")
# using method 1
excess_attenuation(X = playback_est)
# using method 2
excess_attenuation(X = playback_est, method = 2)
}
# }
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