murmur

她发出一声表示同意的低语作为回应。

She responded with a quiet ___murmur of agreement.

我能听见门后传来低沉的说话声。

I could hear the low ___murmur of voices from behind the door.

她低声回应，以免打扰他人。

She responded with a gentle ___murmur to avoid disturbing others.