Ohhh I think I know the answer! (that is a rare event for me TeeHee)

Anyway - watch your "tech counter" and each time it registers another point(s) it chimes (sounds like bamboo wind chimes?)

Let me know if this is the one you are talking about.

I STILL have NEVER heard the "chime" that others talk about when a collectable shows up - and I even turned the sound effects up higher.