Definition of "Murmur" :

noun: a schwa that is incidental to the pronunciation of a consonant

noun: a complaint uttered in a low and indistinct tone

noun: a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech

noun: an abnormal sound of the heart; sometimes a sign of abnormal function of the heart valves

verb: make complaining remarks or noises under one's breath

verb: speak softly or indistinctly

"She murmured softly to the baby in her arms."