How/where would I add sounds for the notifications for Mattermost clients in the repos?

How/where would I add sounds for the notifications for Mattermost clients in the repos?: I think many people are finding that the existing six sounds for Desktop Notifications to be difficult to use/hear. This has been one source of ongoing complaining I've heard for years based upon the default bing and now the other sounds are really no better in terms of quality and intrusiveness. A couple folks even have misophonia and simply have to live with all alerts off (since all six of the sounds trigger a mental/emotional response for them).