The remit of this work was to make some relaxing music which also indicated breathing so that the user would almost automatically breathe in time, without having to follow a count.
I used an audio engine written in libpd to trigger different samples each time, so that the music experience was slightly different on each use. Also, there is the idea of breathing "correctly" to maximise the benefits of the deep breaths. If the user breathes with correct timings, the images come into focus and the music plays more layers.
Grossman, E et al indicate that deep breathing can lower blood pressure, and stress levels (2001).