30+ times for Gringotts, prolly something similar for Spidey. I've had the audio issue four or five times on Gringotts. Never noticed any significant audio problems on Spidey. Volume seems to fluctuate occasionally from ride to ride, though I've never encountered anything as awful as Gringotts' issues.
I believe Gringotts' problem is isolated to the front speakers and is only on certain vehicles at a given time (I rode twice in a row once on the same vehicle and had busted audio both times). The rear speakers for each row seem to output dialogue and little else. The front speakers seem to handle sound effects and music, which are 80-90% muted when the issue occurs. Dialogue has always been present and clear for me, even when the front speakers are busted.
Just my perceptions.
Sounds like a relevant issue to me then. I wonder where the audio comes from... a computer on board the RV or does it come from a more central source elsewhere? I will have to ask. Fascinating.