i think its recommended to import .wav PCM- 16 bit files to your projects instead of importing just ogg vorbis format. because when you import a wav audio , construct will convert it to 2 format m4a ( which supported by some browsers like safari and internet explorer) and ogg vorbis format ( which supported by the famous browsers) , but if you upload just ogg audio, construct will not convert it to m4a ( so sound may not working in some browsers) it convert it to ogg only.
this is how to import audio as mentioned in manual : scirra.com/manual/52/import-audio
i think you can convert your mp3 audio files to .wav also with VLC