No sound
- Depending on the smartphone app (which requires HFP (Hands-free Profile)/HSP (Headset Profile)), you may hear a voice from only one unit.
- Check that the connected device and both the left and right units of the headset are turned on.
- Check that the headset and the transmitting Bluetooth device are connected via Bluetooth A2DP.
- Turn up the volume if it is too low.
- Check that the connected device is playing back.
- If you are connecting a computer to the headset, make sure the audio output setting of the computer is set for a Bluetooth device.
- Pair the headset and the Bluetooth device again.
- Set the headset into the charging case and close the lid of the charging case.
You may be able to resolve some issues by setting the headset into the charging case. - Reset the headset.
- Charge the headset. Check if the sound is output from the headset after charging.
- Initialize the headset, and pair the headset and the device again.
Low sound level
- Turn up the volume of the connected device.
- You can adjust the volume on the headset during music playback.
- You cannot adjust the volume during a call on the headset. Adjust the volume on the connected device.
- Connect the Bluetooth device to the headset once again.
https://helpguide.sony.net/