as clear as a bell 非常清楚；十分清晰；极为清晰的

【例句】
She was in Australia but I could hear her voice as clear as a bell.
她虽然在澳大利亚，但我却能非常清楚地听到她的声音。

I sit the last row, but I still can hear as clear as a bell when the teacher is speaking.
虽然我做在最后一排，但在老师讲课的时候，我还是能听的一清二楚。