I can confirm. Audio is broken in Firefox 25.
It only affects longer audio files in my case (music). After loading for the first time they start playing but stop after about a second.
Now I installed FF 26 beta which reduced/removed the terrible noise and I found a temporary workaround. For my prototype i was able to do it the following way:
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Function On "startmusic"
> Audio | Play mymusic looping from Music at 0 db (tag "music")
> System | Wait 0.1 seconds
> Audio | Stop "music"
> Audio | Play mymusic looping from Music at 0 db (tag "music")
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Not a beutful "solution" - I know. Will remove it again as soon as this FF bug is fixed.
I am not happy about the FF team not testing thoroughly enough before such a radical change/update. But it shows that audio is not a big issue (yet) for a big part of the webcommunity. I can not imagine the same thing happening to the displaying of graphics or fonts.
However the new standard is necessary and I hope that technology will then stay with us for a long while.