AirPods tweet and chirp when in Hearing Aid mode

I returned my 'Pro' EarPods and an audio test confirmed the problem. the tech said it was the first he had seen. He replaced my old ones for new. I updated the hearing test from the older units and again; they frequently and intermittently tweet and chirp with a very sharp sound. So, is this an audio defect in all EarPods? I cannot use them as intended to hear better. Dave Purcell

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