Definitely! Especially in breaststroke, when there's such a huge sound differential between having your head completely underwater and completely out of the water for a longer period of time than the other strokes. It certainly depends on the decibels, though. I imagine the crowd in London during a WR swim is audible to a much greater extent than, say, the parents at an 8 & under summer league competition. But those kids can absolutely still hear the cheers!
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