# timeFrequencyScattering

## Description

Use `timeFrequencyScattering`

to create a joint time-frequency
scattering network using Morlet wavelets.

## Creation

### Description

creates a
joint time-frequency scattering (JTFS) network with default property values.`jtfn`

= timeFrequencyScattering

sets properties using
one or more name-value arguments. For example, `jtfn`

= timeFrequencyScattering(Name=Value)```
jtfn =
timeFrequencyScattering(FrequencyQualityFactor=2)
```

creates a network that uses
two frequential wavelet filters per octave. You can set properties in any order.

Properties become read-only after you create the network.

## Properties

## Object Functions

`scatteringTransform` | Wavelet joint time-frequency scattering transform |

`scatteringFeatures` | Joint time-frequency scattering feature tensor |

`filterbank` | Joint time-frequency scattering filter bank |

`filterpadding` | Joint time-frequency scattering filter padding |

`scattergram` | Visualize joint time-frequency scattering coefficients |

`littlewoodPaleySum` | Littlewood-Paley sum for JTFS filters |

`numFirst2SecondFilterBank` | Number of paths from first- to second-order time wavelet filter bank in joint time-frequency scattering network |

## Examples

## Tips

A large percentage of the computational burden of the JTFS algorithm comes from the element-wise multiplications, Fourier transforms, and inverse Fourier transforms. If you find the empirically determined filter lengths too long, consider setting

`TimeMaxPaddingFactor`

and`FrequencyMaxPaddingFactor`

to`0`

or`1`

. Depending on the padding factors, you might see a warning at object construction. To diagnose whether the reduced padding length is adequate given your network specifications, use`filterpadding`

.

## References

[1] Andén, Joakim, Vincent Lostanlen,
and Stéphane Mallat. “Joint Time–Frequency Scattering.” *IEEE Transactions on Signal
Processing* 67, no. 14 (July 15, 2019): 3704–18. https://doi.org/10.1109/TSP.2019.2918992

[2] Lostanlen, Vincent, Christian
El-Hajj, Mathias Rossignol, Grégoire Lafay, Joakim Andén, and Mathieu Lagrange.
“Time–Frequency Scattering Accurately Models Auditory Similarities between Instrumental
Playing Techniques.” *EURASIP Journal on Audio, Speech, and Music
Processing* 2021, no. 1 (December 2021): 3. https://doi.org/10.1186/s13636-020-00187-z

[3] Mallat, Stéphane. “Group Invariant
Scattering.” *Communications on Pure and Applied Mathematics* 65, no. 10
(October 2012): 1331–98. https://doi.org/10.1002/cpa.21413

## Extended Capabilities

## Version History

**Introduced in R2024b**