How do I improve voice call quality on the KD-SR86BT during a Bluetooth phone call?

While on a call, press and hold the menu button to access voice quality settings. You can adjust [MIC GAIN] from LEVEL -10 to LEVEL +10 (default -04), [NR LEVEL] for noise reduction from LEVEL -05 to LEVEL +05 (default 00), and [ECHO CANCEL] for echo cancellation from LEVEL -05 to LEVEL +05 (default 00). Adjust each setting until the least noise or echo is heard during the conversation. (Page 22)