Spectral moments (CoG, SD, skewness, kurtosis) — trk_spectral

Extracts the four spectral moments — center of gravity, standard deviation, skewness, and kurtosis — as time-series tracks via Praat's spectrogram in pladdrr. Spectral moments characterize spectral shape and are widely used for consonant place-of-articulation and voice quality analysis.

Usage

trk_spectral_moments(listOfFiles, beginTime = 0, endTime = 0, windowLength = 0.005, maximum_frequency = 0, time_step = 0.005, frequency_step = 20, power = 2, windowShape = "Gaussian1", relativeWidth = 1, toFile = TRUE, explicitExt = "spm", outputDirectory = NULL, verbose = TRUE)

Arguments

listOfFiles: Character vector of audio file paths. Any format supported by av is accepted; non-native inputs are transcoded automatically.
windowLength: Numeric. Spectrogram analysis window length in seconds. Default 0.005 s.
maximum_frequency: Numeric. Highest frequency included in moment calculations in Hz. Set to 0 to use the Nyquist frequency. Default 0.
time_step: Numeric. Frame shift in seconds; sets output frame rate (1 / time_step Hz). Default 0.005 s (200 Hz).
frequency_step: Numeric. Frequency resolution of the spectrogram in Hz. Default 20 Hz.
power: Numeric. Exponent applied to the amplitude spectrum before computing moments. Default 2 (power spectrum).
windowShape: Character. Window shape for audio extraction. Default "Gaussian1".
relativeWidth: Numeric. Relative width of the extraction window. Default 1.0.
toFile: Logical. If TRUE, write SSFF output files and return the paths written (invisibly). If FALSE, return an AsspDataObj. Default TRUE.
explicitExt: Character. Output file extension. Default "spm".
beginTime: Start time for the extracted portion in seconds. Default: NULL (beginning of signal). Note: uses beginTime/endTime (seconds) matching DSP function conventions, unlike read_audio() which uses begin/end.
endTime: The end time of the section of the sound files that should be analysed (in seconds). Use 0 for end of file.
outputDirectory: The directory where the slice file should be stored. If not defiled (NULL), the sparse slice file will placed in the same folder as the media file.
verbose: Logical. Show a progress bar (sequential path) or a progress-aware parallel apply (pbapply/pbmcapply, if installed).

Value

If toFile = FALSE: an AsspDataObj with tracks:

cog: REAL32, Hz, n_frames x 1. Spectral center of gravity (spectral mean).
sd: REAL32, Hz, n_frames x 1. Spectral standard deviation (spread).
skewness: REAL32, dimensionless, n_frames x 1. Spectral skewness (asymmetry).
kurtosis: REAL32, dimensionless, n_frames x 1. Spectral kurtosis (peakedness).

Frame rate: 1 / time_step Hz (default 200 Hz). If toFile = TRUE: character vector of output file paths, returned invisibly.

Examples

if (FALSE) { # \dontrun{
# Extract spectral moments
result <- trk_spectral_moments("speech.wav", toFile = FALSE)

# Access tracks
plot(result$cog, type = "l", main = "Center of Gravity")

# Write to file
trk_spectral_moments("speech.wav", toFile = TRUE)
} # }