“bell”是“铃”或“钟”，这两种东西发出来的声音非常响，可以传到很远的地方，因此as clear as a bell所表达的含义就是“非常清楚，十分清晰”。

【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。

Through the wall, I could hear the neighbors talking, just as clear as a bell.
隔着墙，我可以非常清晰的听见邻居交谈。