Narrow-Band Activity Index for Files in a Folder — nbai

NBAI describes the relative amount of narrow-band persistent sound activity, like that of Cicadas and Orthopterans. This index can be used to evaluate insect activity and their influence on other soundscape metrics (e.g., summary acoustic indices).

Usage

nbai_folder(
  folder = NULL,
  recursive = FALSE,
  list = NULL,
  start = 0,
  end = 1,
  unit = "minutes",
  channel = "each",
  hpf = 0,
  freq.res = 50,
  cutoff = -60,
  activity.cutoff = 10,
  output.csv = "nbai_results.csv",
  n.cores = -1,
  verbose = TRUE
)

Arguments

folder: Character. The path to the folder containing the wave files to analyze.
recursive: Logical. Whether to search in subfolders. Default is TRUE.
list: An optional list (subset) of files in the folder to analyze.
start: numerical. Where to start reading the Wave.
end: numerical. Where to end reading the Wave.
unit: character. Unit of measurement for 'start' and 'end'. Options are 'samples', 'seconds', 'minutes', 'hours'. Default is 'minutes'.
channel: Character. If Wave is stereo and you want to use only one channel, pass either "left" or "right" to this argument. If you want to analyze a mix of both channels, select "mix". If NULL (default), results are returned for each channel.
hpf: Numeric. High-pass filter. The default (500 Hz) should be used always for consistency unless signals of interest are below that threshold.
freq.res: Numeric. Frequency resolution in Hz. This value determines the "height" of each frequency bin and, therefore, the window length to be used (sampling rate / frequency resolution).
cutoff: Numeric. Cutoff threshold defining the sounds that will be analyzed, in dBFS.
activity.cutoff: Numeric. Cutoff percent activity. Only the frequency bands active equal or above this percentage will be considered as "active" in the active band statistics.
n.cores: The number of cores to use for parallel processing. Use n.cores = -1 to use all but one core. Default is NULL (single-core processing).
verbose: Logical. If TRUE, details of dynamic range will be printed on the console.

Value

A list containing: 1) A binary spectrogram (if mono), 2) tibble with the Narrow-Band Activity Index (NBI) summary statistics, and 3) a tibble with NBI spectral, which number of rows equals the number of frequency bins in the analysis.

Examples

if (FALSE) { # \dontrun{
nbai(wave, channel = 'left', plot = TRUE, verbose = TRUE)
} # }