# audioDelta

## Syntax

## Description

specifies the delta window length.`delta`

= audioDelta(`x`

,`deltaWindowLength`

)

specifies the initial condition of the filter.`delta`

= audioDelta(`x`

,`deltaWindowLength`

,`initialCondition`

)

`[`

also returns the final condition of the filter.`delta`

,`finalCondition`

] = audioDelta(`x`

,___)

## Examples

## Input Arguments

## Output Arguments

## Algorithms

The delta of an audio feature *x* is a
least-squares approximation of the local slope of a region centered on sample
*x*(*k*), which includes *M* samples
before the current sample and *M* samples after the current sample.

$$delta=\frac{{\displaystyle \sum _{k=-M}^{M}k\text{\hspace{0.17em}}x(k)}}{{\displaystyle \sum _{k=-M}^{M}{k}^{2}}}$$

The delta window length defines the length of the region from –*M* to *M*.

For more information, see [1].

## References

[1] Rabiner, Lawrence R., and Ronald
W. Schafer. *Theory and Applications of Digital Speech
Processing*. Upper Saddle River, NJ: Pearson, 2010.

## Extended Capabilities

## Version History

**Introduced in R2020b**