# spectralEntropy

Spectral entropy for audio signals and auditory spectrograms

## Description

specifies options using one or more name-value arguments.`entropy`

= spectralEntropy(`x`

,`f`

,`Name=Value`

)

`spectralEntropy(___)`

with no output arguments plots the
spectral entropy. You can specify an input combination from any of the previous syntaxes.

If the input is in the time domain, the spectral entropy is plotted against time.

If the input is in the frequency domain, the spectral entropy is plotted against frame number.

## Examples

## Input Arguments

## Output Arguments

## Algorithms

The spectral entropy is calculated as described in [1]:

$$\text{entropy}=\frac{-{\displaystyle \sum _{k={b}_{1}}^{{b}_{2}}{s}_{k}\mathrm{log}\left({s}_{k}\right)}}{\mathrm{log}\left({b}_{2}-{b}_{1}\right)}$$

where

*s*is the spectral value at bin_{k}*k*.*b*_{1}and*b*_{2}are the band edges, in bins, over which to calculate the spectral entropy.

## References

[1] Misra, H., S. Ikbal, H. Bourlard,
and H. Hermansky. "Spectral Entropy Based Feature for Robust ASR." *2004 IEEE International Conference on Acoustics, Speech, and Signal Processing*.

## Extended Capabilities

## Version History

**Introduced in R2019a**