Click on the image below to view it full size in an image viewer !
PLAYlogo: RingCycle~.pd

This is the heart of the basic sound; each circle/ring has an index which influences it's frequency (possibly harmonic) above the base frequency. However, at any given time tick the frequency is scaled by the visual brightness 0..1 of the rings ! In combination with the sense of expansion in time afforded by the expanding circle wav", this is the deliberate binding between the visual rings and and the aural synthesis that gives the logo its "meaning".

Forgive please the intended Wagnerian "ring cycle" pun, not least because this is not quite true ring modulation. The PLAY logo does have rings of course.