Normalized Difference Soundscape Index
This function computes the Normalized Difference Soundscape Index as described by Kasten et al. (2012).
NDSI(x, anthropophony = 1, biophony = 2:8, max = FALSE)
x |
a two-column numeric matrix computed with |
anthropophony |
a numeric vector defining the frequency band(s) of the anthropophony (in kHz). |
biophony |
a numeric vector defining the frequency band(s) of the biophony (in kHz). |
max |
a logical, if |
NDSI aims at estimating the level of anthropogenic disturbance on the soundscape by
computing the ratio of human-generated (anthropophony) to biological
(biophony) acoustic components found in field collected sound
samples. In terms of frequency, the anthropophony is defined as the [1-2[
kHz frequency bin and the biophony as the [2-8[ kHz frequency bins of a
soundscape frequency spectrum (see soundscapespec).
NDSI is computed according to:
NDSI = (biophony - anthropophony) / (biophony + anthropophony)
NDSI varies between -1 and +1, where +1 indicates a signal containing
no anthropophony.
A numeric vector of length 1 giving the NDSI value.
Jerome Sueur
Kasten, E.P., Gage, S.H., Fox, J. & Joo, W. (2012). The remote
environmental assessment laboratory's acoustic library: an archive for
studying soundscape ecology. Ecological Informatics, 12, 50-67.
## Note that 'tico' is not a soundscape recording... data(tico) spec <- soundscapespec(tico, plot=FALSE) NDSI(spec) NDSI(spec, max=TRUE)
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