
You are in the middle of a conversation when it starts: a thin, high-pitched whistle coming from your own ear. Everyone nearby can hear it too, which makes it ten times more embarrassing. That whistling is called acoustic feedback, and it happens when amplified sound leaks out of your ear canal and gets picked up…

That sudden squeal when you put your hearing aid in, the whistle when someone hugs you, the high-pitched tone that appears out of nowhere during dinner: all of it is acoustic feedback. It is the single most common complaint among hearing aid wearers, and it is also one of the best-understood problems in hearing science.…