Program sndc sends to dgnsd server requests about playing sound. Server dgnsd sends the request to one's graphic clients, which are xdgnp applications. Massages, that are sent by sndc can be double:

Text is played using the speech synthesizer. When a sound file is played, you should give a path to it. Each path is automatically preceded with a directory where sound files of David system are located (default: /usr/share/david-system/sounds). Thus giving the file alarm.wav causes the graphic client understands that as a file /usr/share/david-system/sounds/alarm.wav.