If a piece of music is atonal, it is not built on one home key. In most songs you already know, one note feels like home, and the tune likes to return there. Atonal music does not work that way. You still hear notes, loud or soft, but no single pitch is the boss. Though actually, people stretch the word. Music teachers may keep it for a modern style from the early 1900s, when some composers stopped using keys. Everyday listeners may call any tune that feels strange or not catchy atonal, even when a key is still there. It never means no sound, and it never means no colour in the sound. It means not in a key.

無調性的（音樂不建立在某個調上）。不是「沒有聲音」，也不是「沒有音色」。