If there is no sound from the capsule 3 or the mars 3 air, please try the following steps to see if they help:

1. Switch between various projection modes to see if your projector can play sound. 

2. Press the Volume Up button on top of your projector.

3. Restore the projector's default settings by going to Settings > System > Restart

4. In Projection Mode, connect your projector to an external Bluetooth speaker by going to Setting>Remotes & Accessories>Pair accessory

If the issue persists,  please contact us for further assistance.