When I use live view, a loud tapping echo sound comes through the camera even though I have two-way sound turned off.
That is odd to hear @jac_214! If two way audio is not engaged, the only sound will be from the Cam’s mic unless this is also muted (in most cases it is not). The sound could be from wifi signal interference, in which our Community post about RSSI can help you optimize.
Please also ensure bluetooth and VPN are disabled on your mobile device. I hope this helps!