A Murmur

1. (countable, uncountable) Any low, indistinct sound, like that of running water.
2. (countable, uncountable) Soft indistinct speech.
3. (cardiology, medicine) The sound made by any condition which produces noisy, or turbulent, flow of blood through the heart.
4. A muttered complaint or protest; the expression of dissatisfaction in a low muttering voice; any expression of complaint or discontent