i use <audio> tag to play .wav files.
it is working right in Chrome and old Firefox,
in firefox 16.0.1, some of these .wav files can not play. error message is: 媒体资源.....无法被解码
It is possible that the .wav files are encoded in an unsupported format: Media resources ..... can not be decoded.
Maybe try to recode the files if you use some kind of compression format.
I too got this issue.
Fixed by changing Mono -> Stereo while converting.