I wonder the same as you...never been on them though...but I hate going on a new aircraft type and not knowing what the chime means...I was on an A330 My travel and a Red Light came on, during turbulence...I think someone said on a forum that it was just a call from the cockpit...
As for the chime you had...I'm not sure, but on a Boeing...the sound of a seatbelt sign...on off on off on off (6 chimes) would mean big emergency...