Should it not be the responsibility of the SCCM to make sure it is audible? Do you check the PA volume before the flight? It just seems hypocritical to get shirty with passengers who don't listen when they can't even if they want to...
That's a very good point and I have long wondered what the CC would do if you informed them that the safety briefing is inaudible as I know all CC take safety briefings very seriously.
To illustrate this point, I have had two safety demo experiences recently. The first was on a Thomson flight where, almost at the end of the 'manual' safety briefing the CC member doing the audio noticed a passenger coming out of a toilet. He promptly started the briefing again.
The second was on a Monarch flight where the safety briefing was a recording and shortly before the end, the recording stopped unexpectedly. The crew immediately commenced a 'manual' briefing which required the aircraft to pull into a holding area and wait for the completion of the briefing.