ANC mic in right ear gives off high-pitched whining that is deafening.

I may have found the solution to my headphones making this high pitch noise.

I've undergone quite a few replacements in my hunt to track down the problem component. I have replaced the internal feedback microphone with an OEM microphone. In the process, I accidentally broke the headband and replaced that. However, the feedback persisted.

In the teardown process, I accidentally damaged the right ear diver and replaced it. During this repair, I also replaced the internal feedback microphone with these replacements https://www.amazon.com/dp/B00LZV1ERG. Unfortunately, they were quite difficult to solder to the wires, and when successfully connect produced a VERY strong noise canceling effect that was very uneven from the undamaged left mic/driver.

The last microphone I tried in place of the original microphone was a gutted external feedback microphone.

With a crafting knife, I scored and removed the rubber. Do pay special attention to the positive and negative terminals, since they are not marked on the microphone itself. I soldered this microphone in place of the original, taking care not to expose the replacement to too much heat. I then reset the XM4s to factory settings and recalibrated the noise canceling.

Since replacing my internal microphone with this one I have not experienced the intense feedback. This is with typical use over the course of two weeks. The feedback would be exacerbated when the headphones were left out in cold humid rooms, when left charging overnight, or when the earpiece was left "half-off" my ear. In all circumstances that would typically produce feedback, I am longer getting any!!

Do note that this is technically a modification of two variables - a replacement of the driver and a replacement of the microphone. Though, hopefully others can provide their feedback and experiences.

Update (06/14/2023): Replacing the internal microphone with the gutted external feedback microphone has stilled worked!

I had this issue too and of course it started immediately after 1 yr warranty. I tried all the usual without success and as a last ditch attempt replaced the earpads with wicked cushion brand ones (fake leather ones not the fleece) and so far so good. I cannot explain exactly why, I had taken them apart previously and reinstalled old earpads and that did nothing to help. Potentially extra sound leaking because my old ear pads are super well worn because I use my headphones several hours a day and the new ones are tight. Keeping fingers crossed the magic continues.

In my case, the mic had actually fallen out of it's mount under the right earcup, as seen in the photo, where the plastic piece that holds the mic in place has also fallen off. In my case, this lack of plastic piece has allowed the mount for the mic to pierce through the foam, but so far, it doesn't seem like this has caused any problems.

Follow the iFixit guide to remove the earcup, and then peel the foam back to check that the mic is still in it's mount and secured down with the plastic piece. If your foam is torn, make sure you remove any loose bits of foam. For comparison, my left earcup looks like this, with the mic secured into place (it should sit vertically in the mount).

Fixed. This issue is caused by a feedback loop creates from the glue on the mic heating up due to body heat and melting and creating an area inside the headset where feedback occurs.

This will fix it.

1. Gently take off the headphone cup (I used a credit card to wedge it open all around the cup)
2. Remove the foam protector
3. With tweezers carefully remove the white plastic mic protector being careful not to rip it. It will come off but takes a little doing to come loose so with it from all sides
4. With tweezers carefully lift out the mic, a round 3mm metallic mix with a glued on circular fabric protector
5. Remove that piece of fabric with tweezers and discard it. It’s not needed
6. With alcohol wipe and clean the area. I dipped a piece of Bounty in vodka. Not too wet, just enough to clean it. Make sure ask the glue is gone
7. Before putting the mic and white cap back make sure the two copper wires going into the mic are not touching. You can separate them with a toothpick if they are
8. Put everything back together and your problem is going to be fixed

I repair this loud distortion at my shop on Long Island.

http://installments-payment-plan-financi...

This is caused by the ANC microphone located in the ear cup of the side emitting the loud noise. It's a feedback loop. It's likely moisture causing the issue. Blowing hard on the ear cup can cause the problem to go away but it's temporary. Anyone have a parts source for the ANC microphone in the ear cup?

The high pitched sound is caused by the feedback loop.

The earbuds have a tiny piece of sponge/mesh inserted into the end tube. By end tube I mean a tube ending with plastic ear tip that goes into your ear canal. The speaker is inside that tube. In my case, left earbud had the tiny sponge, and right earbud didn't have it. I presume that it somehow got detached and went missing during the course of exploitations.

For me the solution was to reproduce the same tiny sponge and inserting it into the right ear bud. I used a piece from a dish sponge and shaped it with scissors to re-create exactly the same length and shape. It is not difficult but required some precision. I used a droplet of superglue at the side of the sponge to have it glued into the inner side of the tube permanently - to reduce the loglikelihood that the sponge would get dislodge in the future.

It worked. No feedback loop and both earbuds work flawlessly with noise cancelling back to normal.