Dear Valued Sony Customer:
It has come to our attention that some customers using the MDR-NC50 noise canceling headphones might experience poor audio quality including mono sound (sound from one side) or a howling noise. The headphone cord may easily fall out of the headphone jack.
Cause: The headphone plug has not been inserted all the way into the headphone jack.
Solution: There is a line on the plug which should almost disappear when the plug is inserted all the way into the jack. A loud click should be heard when inserted correctly.
Please refer to the pictures below.
The plug is not completely inserted in the jack. The line does not meet the headphone jack.
The line is right up to the headphone jack.