Sounds on the Internet are currently not as popular as pictures for example. Why ?
Because of the:

But in the near future with the development of the multimedia computers, sound will become an important issue. Moreover, the development of telephony and radio broadcasting over the Internet will attract a lot of people.

The sound on the Internet is still at its first step ... Wait 1 or 2 years and you'll see :) MP3 format is slowly coming ...