On the Web Tools toolbar, click Sound .
In the Sound box, enter the path or Web address of the sound file you want, or click Browse to locate the file.
In the Loop box, enter the number of times you want the background sound to repeat.
Notes
To turn off a background sound while you are authoring a Web page, switch to Design mode. To turn on a background sound, exit Design mode.
For others to hear background sound, they must have a sound card installed on their computers and their Web browser must support the sound format of the file you inserted. You can insert sound files in WAV, MID, AU, AIF, RMI, SND, and MP2 (MPEG audio) formats.
The background sound plays automatically every time your page is opened or returned to. To prevent repetition, insert a hyperlink that the user can click to download the sound file.
When selecting Infinite for a looping option, keep in mind there is no way to stop the sound when viewing the page in a Web browser.
This is all I have found for outlook xp. Which version of outlook are you running?
Thanks.