Murmuration and Thrum

Murmuration noun - A low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech.

Thrum and murmuration are semantically related. In some cases you can use "Thrum" instead a noun "Murmuration".

Thrum noun - A monotonous sound like that of an insect in motion.

Murmuration and thrum are semantically related. Sometimes you can use "Murmuration" instead a noun "Thrum".