On the LabQuest 2 and LabQuest 3 there is an option to have the LabQuest make sounds when you press keys such as the power button. By default these are disabled on LabQuest 2 and enabled on LabQuest 3. The default setting and be changed from the Audio app.

LabQuest 2⚊Tap Home > Preferences > Audio
LabQuest 3⚊Tap Audio from the Settings screen

Tap the System Sounds checkbox to change the setting.