I am considering buying a front and rear dashcam for my, new to me, car but I have a habit of always singing when I'm driving, will it record this? as I am no Celine Dion :)
I think it's useful as I tend to make audible comments when I spot hazards (as does gness if she's in the co-pilot seat) and so it could let any person reviewing the footage know that we were paying attention.
I have my microphone off. A viewer would be shocked by my comments on other road users when I am unimpressed by their actions.
I don't think that a video of an incident would in any way be improved by a sound recording anyway.