细小的声音可以用英语中的 "faint sound" 来表示。

"Faint" 是形容词，意思是 "微弱的，轻微的"。例如：

I could hear a faint sound coming from the next room. (我能听到从隔壁房间传来的微弱声音。)
She spoke in a faint voice, barely audible. (她的声音很微弱，几乎听不到。)

"Sound" 是名词，意思是 "声音"。例如：

The sound of the water rushing through the pipes was soothing. (水在管子里流动的声音很放松。)
The sound of the wind howpng through the trees was eerie. (风在树林中呼啸的声音很怪异。)

所以 "faint sound" 就表示 "微弱的声音"。