Bose A20 Background Squeal Noise

[Roll Tide]

For the last six months my three-year-old Bose A20 headphones with plane powered LEMO jacks have developed a background chattering squeal that to me sounded like radio interference. When powering up, the noise reduction comes on and they are quite for about ten seconds or so and then the noise begins. I’m usually on my way somewhere and haven’t really stopped to troubleshoot because other than being annoying they work fine. A second pair I use for the right seat work fine but I didn’t want to blue tooth them to my phone which I use to call for clearances.
I’m going in for annual this week so I started the troubleshooting, swapping headphones around… I found that the headphones made the noise plugged in or not. I was relieved to find the plane wiring was not the problem and decided I needed to send them in for service. I went to the Bose website and ran through their checklist which was pretty much what I already did. When it said to install new batteries, I was skeptical as the headphones are powered by the plane and seem to work on the current Energizer AAs, not lithium. To be thorough, I swapped in a new pair of Duracells and the background noise was gone. Simple fix!
A web search showed issues with AA lithiums but I couldn’t find much on this so I decided to post if anyone else had this nagging background sound. In hindsight, I should have been more proactive a while back.

 

[cappy48]

 

[Orest @ CYFD]

 

[cappy48]

 

[Ogie_ogelthorpe]

 

[cappy48]

 

[Arrow4]

 

[Aviator305]