Sound4:

How to use it: This inserts the a sound embedding script into a document, complete with the sound file. Use it whenever you wish to always use a particular sound (either mid or wav) with a piece of stationery. This script contains one of my disappearing comments in the OE compose window.  This comment serves to mark the location of the sound file itself and also protects the script from accidental deletion.

You can also easily set the number of times that your sound will repeat.   In the script itself you will notice this line:

<bgsound id="sound" src loop="1">

Notice the loop="1" portion at the end of that line?  That tells your sound to play once.  By altering this line you may change the number of times that the sound plays, for example, loop="3" would cause the sound to play thrice. 

To achieve an infinite loop, set this to loop="-1".