I've got some wavs that I converted to mp3s. I can hear them just fine on my PC, but when I try to play them using the flowplayer3 plugin I get no sound.

I get a similar problem with videos, but I was able to work around that by converting the videos to flv.

check the flowplayer site. MP3 is a container, not a recording format, so maybe flowplayer has problems with the internal format.

Just to "fix". mp4 is a container, mp3 is very well a format..;-)

Flowplayer3 is flash based and only supports standard codecs and settings Flash supports. As my colleague said the flowplayer site has info about that.

As I just see the site has changed and is now found on:
http://flash.flowplayer.org/

Flowplayer5 is a new HTML5 player with Flash fallback and not apdated for a plugin yet (mostly because the dev choose to drop mp3/audio support).

I used Free converter to convert the files. According to GSpot the codec it used is MPEG-1 Layer 3. Does anyone know of a free audio conversion utility that will let me force it to use a specific codec and/or which codec I should be using?

It is not only the codec, it is also the setting. Flash has problems with odd resuolutions. You should stick to something plain like 44khz 16bit 128/256kpbs for example.

I am on Mac and therefore just use iTunes. Also I use on Mac free programs like Miro (uses ffmegX internally, also video), XLD or xACT.

Thanks! I'll try changing the resolution and check those out editors.

As for audio conversion utility, you can also use AppGeeker.
<link removed>
It can convert most common audio and video formats (flv, mp4, mp3, ogg, flac, wav, etc) easily with predefined templates/presets.

Please no advertising for paid software. There are lots of free tools as well. Thanks.