In the latest release Gravitarium Plus v2.5.7 you have the option to use your device's microphone as the beat sensor instead of using the iTunes lib as described bellow. To use this option simply tap the little MIC icon in Audio settings to the ON state. Afterwards, with the Dancing and Sticky Flow ON, you will be able to manipulate the particles with your own voice or any other media playing in the background!
First Create your own Playlist:
Select Audio and tap iTunes Lib at the top.
Select individual songs, artists, albums or existing iTunes playlists to add and click Done. (Please note only songs physically downloaded to your device via iTunes will work this way, use the MIC external beat detection for any other songs or playlists.)
The audio section will now have your songs and will start playing!
Now to turn on the beat detection visualizer:
Tap Options and switch "Dancing flow" to the On position, if you want the visualizations to stick - turn the "Sticky flow" switch ON as well.
Tip: Try and play with different settings - e.g. with Size set to 5.0, Tail and Speed at 1.0 and Opacity at 0.5 you can make some interesting colorful visuals from your tracks :-)