Spectral slope for audio signals and auditory spectrograms
The spectral slope is calculated as described in [1]:
where
fk is the frequency in Hz corresponding to bin k.
μf is the mean frequency.
sk is the spectral value at bin k.
μs is the mean spectral value.
b1 and b2 are the band edges, in bins, over which to calculate the spectral slope.
[1] Lerch, Alexander. An Introduction to Audio Content Analysis Applications in Signal Processing and Music Informatics. Piscataway, NJ: IEEE Press, 2012.