Hum and Murmuration

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

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

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

Hum and murmuration are semantically related in low topic. You can use "Hum" instead a noun "Murmuration", if it concerns topics such as murmur.