When you chew, you hearing canal actually changes shape. You can test this yourself by placing your pinky finger into your earcanal, then opening and closing your mouth (make sure you take your hearing aid out first). When your earcanal changes shape, this can often lead to amplified sound leaking out of your earcanal around the sides of a custom-molded hearing aid or earmold. When sound leaks out of your ear, some of it will be picked up by the hearing aid microphone, leading to re-amplification of already amplified sound. We call this phenomenon acoustic feedback, and it can be a real nuisance. Newer hearing aids, with advanced feedback suppression, are much better at handling this situation, but depending on the amplification levels involved, it can be very difficult to stop completely. I would return to your hearing provider and discuss the issue with them. They may be able to improve your custom mold or run the feedback calibration test while your jaw is open, to reduce the likelihood of this happening. If your hearing aid has a volume control, you could also try reducing the volume while eating. Lastly, your provider might be able to create a special setting on your hearing aid for you to manually switch to before eating, which could reduce the amplification at the troublesome pitch. Good luck!
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