The four message sounds, the call sounds for joining, leaving, muting, deafening, push to talk and screen sharing, the incoming and outgoing rings, and the eight soundboard sounds are all new and evenly matched in loudness. Your sound settings, chosen speaker, Do not disturb and Reduce sound work exactly as before.
The sounds load after your first click or key press, not before; with Data saving on, each one loads only when it first plays. They are kept for offline use, and if one cannot load, Kemble plays its earlier sound instead.