If you are defining a sound to be played as an action in the Alert Manager, the sound is being executed on the server itself. The requirements are that you would need a sound card and speakers attached to the server itself. If you server is rack mounted and in your data center, this most likely won't do you any good, so if you need the sound to play from the browser, you can edit your Orion web UI account and configure it to play a sound of which you have 3 options by the default configuration. This way when an alert fires, the sounds will play through your browser. This is typically much better for a scenario where you would be displaying the console on a NOC screen (common area) or even at your desk. The requirements though again are that you need to have a sound card and speakers attached. The sounds are .wav files and they are not played on the system speaker.