Good question @F50! There is not a volume adjustment control for these Cams at this time. When actively in a live view, or answering a live event, there are toggles to turn the microphone or the speaker on and off.
Consider this shared with the team, as you are correct, we've seen this request before and your continued interest adds value!
Hey @Gin. Are you ensuring that you are accepting the Live View call? Once you press the green phone icon at the bottom right of the Live View screen, please ensure you do not have the speaker icon muted, so this will eliminate the sound from playing for you. In the event you still cannot hear the Live View, please try turning off any Bluetooth devices that may be controlling the audio. Additionally, some phones treat a Live View like a phone call, and therefore you may need to hold the phone up to your ear to hear the person there and ensure your phone isn't on mute/silent.