a muffled sound的用法和样例：
- A muffled sound resembling that of soft footsteps.
- That's when a muffled sound rolled through the town: whomp.
- A muffled sound of voices floated up from the far end of the graveyard.
- In the stillness of the house, she could hear a muffled sound downstairs.
- To beat with or as if with a blunt object so as to produce a muffled sound or thud.