Hi Peter - assuming that you have sound because of the Audible Alert option, here's how to enable / disable that.  The option can be accessed from the hamburger button on the top left of the Alarm Console.  Note that this is done for the tab page that you have currently open (so you may have to check this option across the various tab pages that you have open).

Configuring a custom alert sound for an alarm tab | DataMiner Docs

Note that there is also a Text to Speech option (accessible via the same hamburger menu) - but I assume that's not the one that you are hearing.