SoundMachine 2.5.2 by Rod Kennedy is a very popular utility that does not convert sounds, but rather plays a wide variety of them. Many users on the Internet using Netscape will more than likly already have SoundMachine as a helper application.
If you are doing anything at all with sounds, it is a good idea to SoundMachine on your Hard Drive. It will play sounds of any lengh and only uses 800K of memory. While some sounds played on SoundMachine sound a little distorted at times, I find that almost every sound file is supported, making SoundMachine a good utility. You can contact the creator at firstname.lastname@example.org