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Bose A20 squealing and whistling

rv8ch

rv8ch

Well Known Member
Patron
During descent on my last few flights I had a strange squeal or whistle in the right earcup on my Bose A20 headset.

I now have some hints to try from this website, but was wondering if anyone else has experienced this? The only "change" lately has been it's pretty darn cold, so perhaps the electronics are acting up, or my headset ear cup is not sealing right. Only happens in the right headset, and only during descent to land.

https://www.boseapac.com/en_in/support/articles/HC2525/productCodes/a20/article.html.html.html.html

someone from Bose on their Website said:
Be sure the headset is being worn properly.

Due to the angle of the earcups, proper left and right earcup placement is essential for the headset to fit around both ears. The headset's performance can be greatly reduced if the earcup fitment around the ears is poor. For more information, see Wearing and adjusting your product.

Determine if any recent changes have been made to the headset or aircraft.

If any changes or modifications have been made to either the headset or the aircraft, look into whether or not those changes could have unexpectedly caused this issue.

Determine if the headset squeals when it is not being worn.

If the headset can be heard squealing when not being worn, your headset may need service. Follow the link below for more information on how to service your headset. Depending on your product and region, you will be provided a contact number or the ability to setup service online.

Check if the issue only occurs at certain altitudes.

In non-pressurized aircrafts, the effectiveness of noise-cancellation decreases as the alititude increases. The headset might also produce a whining sound in these situations. For info on maximum altitude for full noise cancellation, refer to the headset specifications.

Replace worn ear cushions.

The issue may be caused by the lack of a proper seal by the ear cushions around the ear. Also check to be sure the cushions are securely attached to the earcup. Replacing worn ear cushions will aid in comfort, the performance of the active noise reduction and battery life

Determine if the issue occurs when your headset is powered off.

Your headset works in passive mode (powered off with no noise cancellation). If the issue still occurs while the headset is powered off, the issue is related to signal coming being received by the headset from the aircraft panel (i.e. the connections, wiring, or interference).

Your product may need service.

If the steps provided do not resolve your issue, your product may need service. Follow the link below for more information on how to service your product. Depending on your product and region, you will be provided a contact number or the ability to setup service online.
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This may be entirely unrelated, but just some info to consider. I have the Bose noise cancelling earbuds, and started to get a loud howling/squealing in one ear after a few years. Careful examination revealed that the two halves of the shell had started to separate; closing them with my finger made the squeal go away. A bit of CA glue to reseal them and they've been fine.

So perhaps the same is happening on your headset. Look carefully to see if the plastic is cracked or separating. Might be a cause, might not, but worth a look IMO.
 
If not under warranty, Bose will do a complete refurb for about $250. Not sure what the Swiss turn-around time is, but in the US you can get it done in about a week
 
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Are you using lithium batteries?

I was getting noise and the Bose folks at Oshkosh told me not to use anything but alkaline batteries. The lithium ones have too much voltage and will cause noise.

They were right. After I replaced, noise went away.
 
From what you describe

Sounds like feedback. Short story made long; the active noise cancellation senses ambient noise and plays it back as close to 180 out of phase as possible to cancel that energy. Assuming (professor) Bose (RIP) design is like others, there's a mic on the outside of each ear cup and a speaker inside. They can produce feedback/squeal if not isolated from each other.

-> The first item on your checklist. Maybe cold ear cups aren't sealing well; even worn over glasses can create enough void in the isolation to cause problems.

Keep us informed
 
Thanks for the ideas. I use normal batteries, not lithium. Don't wear glasses, but since it was pretty cold, there could be some leaking of sound. Sounds like I have some testing to do when I get back in the air!
 
rv8ch said:
Thanks for the ideas. I use normal batteries, not lithium. Don't wear glasses, but since it was pretty cold, there could be some leaking of sound. Sounds like I have some testing to do when I get back in the air!
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Maybe it's just me, but I've never experienced any sort of feedback or noise when the ear seal isn't "perfect", even including lifting one side completely off the ear, both in flight and on the ground (engine stopped). I've never heard anything weird coming from them when they're taken off at the end of a flight (I have them set to auto-off, so I don't bother to turn them off before removal). No passenger has ever reported a noise cancellation problem due to glasses or a less-than-perfect seal, either.

Maybe I just got several pairs of better-than-average A20s, I dunno.
 
If this is only occurring on descent, I would be looking for something whistling on the airplane at higher airspeeds.
 
airguy said:
If this is only occurring on descent, I would be looking for something whistling on the airplane at higher airspeeds.
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That's exactly what I thought it was the first time it happened, but on my last two flights I removed the headset from my right ear, and the sound was not there any more. Perhaps it's at a frequency that I can't hear with the "naked" ear, but the Bose is picking it up and trying to cancel it.
 
RV7A Flyer said:
Is it only with one headset, or is it still there if you use a different set of A20s?
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I have not tried that - good suggestion. Since Bose has a pretty complete support page on this phenomena I thought that perhaps someone on VAF had seen it...
 
Mickey, any feedback, have you found what the problem was?

Asking since I'm having exactly the same problem now... an unbearable squealing noise that only starts during descent, and only the right side being affected.
Removing the headset, and then wearing it again, has the noise stop, but not every time. I had it start again 1-2 minutes later :(
It started acting about 6-7 flights ago, no change has been done to the batteries, or anything else on the aircraft.
The bluetooth headset is now a few years old and never had a problem, and I replaced the pads etc (as provided in the replacement accessory kit) a year ago due to wear only.
 
Dan 57 said:
Mickey, any feedback, have you found what the problem was?

...
Click to expand...

Strangely shortly after this last post it just stopped, and I have not experienced it since. I cannot think of a single thing that I changed. I think simply writing about it here fixed it - another demonstration of the power of VAF! :D
 
What audio panel do you have? If a '3D' audio one, make sure the copilot side headset jacks don't have something plugged in. Any noise from wind hitting that mike would be in your right earpiece.

Mark
 
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