Responsive music/sound

Hi, I'm Arduino noob and I've got a side project where i like to use responsive sound or music to match the sensor that picks up outside stimulus like movement or footsteps. I'm not really sure on the approach i can use on the music part. Do i use sound samples like KONTAKT where it alters a sound sample to be more intense ? Or do i use Ableton and select some synth and try to make it generative? I would be appreciative if you guys could give me a general low down or general advise on approaches i can consider using, much thanks

Have you used MIDI (like Ableton or KONTAKT) before? I don't use MIDI myself, so I can't help with the details. But, MIDI seems like the way to go. With MIDI you can simulate anything from a quiet solo instrument to a full-on orchestra. (It just can't do lyrics & vocals.) So, you can sense the foosteps, movement, etc, and then your software can determine how many instruments are played, how loud they are, the tempo, or even the song if you want a different song for different situations.

Like I said, I don't use MIDI myself, and I'm nor sure about the Arduino's limitations. Certainly, the Arduino can serve as a sensor/controller (as long as you have some kind of appropriate "footstep sensor", etc.). With the some additional hardware-driver circuitry, it can send MIDI commands to a MIDI instrument (or to a computer) over the MIDI bus.

If you've worked with MIDI, or downloaded MIDI files, you know they are "simple" small files because they only have to contain the notes & timing, not the actual sounds. So... whatever is generating & sending the MIDI commands doesn't have to be powerful with lots of mamory.

The virtual instrument does all of the "hard work". The Arduino itself doesn't have the kind of memory you'd need for lots of high-quality virtual instruments. I'm not sure what's available as an add-on board, but building a MIDI instrument with lots of voices is going to be the complex part and I'm not sure if it can be done with the Arduino.