Distorted sound/Humming or noise in the system output

Turn down the volume of the connected device.
If the connected device has an equalizer function, set it to off.
Keep the system away from a microwave oven, wireless LAN, etc.
Bring this system and the BLUETOOTH device closer together. Remove any obstacle between this system and the BLUETOOTH device.
Keep the system away from a TV.
Switch the BLUETOOTH connection to A2DP by operating the BLUETOOTH device when HFP or HSP is set.
If the BATT/CHG indicator (orange) starts flashing, connect the system to a computer and charge the built-in battery.
If you connect a device with a built-in radio or tuner to this system, broadcasts may not be received, or sensitivity may be reduced. Locate the system farther away from the device and check that you can listen to the broadcasts satisfactorily.