This post comes from guest tipster Jerry Martin:
What I found was that you can create or download an MP3 of your choice and then save it on your hard drive with an PNG extension.
You then create a PNG web resource with this file
In this example I have a horn honk that plays when an entity is opened (totally useless but it’s just an example)
var audio = new Audio(‘https://[instance].crm.dynamics.com//WebResources/hsl_horn‘);
You could have it play when a deal is closed or some other event.