In the old time the only way to interact with music was singing, dancing, whistling, clapping your hands...but all these actions were just aside the music playing and NOT inside.
And now we just jump inside, the simplest and natural way you can imagine: for example you tell something and the music catch it and insert it in its flow...and so with any sound you produce.
This could be all, sound + sound = sound and that it's. No with RjDj the music will follow your steps, your movements: look at this new territory, more applications will come.

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