# Audio Reactivity
This guide explains audio reactivity within modV and how to assign audio features to module props.
Audio reactivity in modV is provided using Meyda, an audio feature extraction library.
In other live visual applications, you are usually presented with the raw FFT and it's mainly up to the user to isolate certain "active" frequencies to assign to parameters.
modV takes a slightly different approach to offer the user more advanced audio analysis in the form of "Features".
# What is an Audio Feature?
Often, observing and analysing an audio signal as a waveform doesn’t provide us a lot of information about its contents. An audio feature is a measurement of a particular characteristic of an audio signal, and it gives us insight into what the signal contains.
Audio features can be measured by running an algorithm on an audio signal that will return a number, or a set of numbers that quantify the characteristic that the specific algorithm is intended to measure. Meyda implements a selection of standardized audio features that are used widely across a variety of music computing scenarios.
(taken from the Meyda website)
Meyda's documentation provides detailed notes on the values returned and what each audio feature does.
# How to use Audio Features
For information on how to use Audio Features in developing a modV Module, please see Writing a 2D Module.