Even a trained ear finds them impossible to place.

A plastic coated cardboard cup, his trained ear told him.

That sound came quite a distance away, but it wasn't difficult for his trained ears to distinguish.

It was hard to tell, even to my trained ear.

"Not yet," she said in a whisper audible only to his trained ears.

His trained ears told him the watch-whistles were about a block to the west and moving fast.

Remo's trained ears picked up a sound off to the right.

Noise reduction also adds some artifacts to the sound, which a trained ear can hear sometimes quite easily.

His trained ears had heard a slight creak from some of those steps.

His trained ears had heard a sound in the large room.