清脆 describes sounds that are clear, sharp, and pleasant, like a bell or a bird's call. It also means 'fragile, delicate' for objects (e.g., thin glass). For sounds, 悦耳 (yuè ěr) focuses on being sweet and melodious; 动听 (dòng tīng) emphasizes being pleasant to listen to. For fragility, 脆弱 (cuì ruò) refers to emotional or physical weakness, while 清脆's 'fragile' sense is purely physical.