RFC 7282 – On Consensus and Humming in the IETF
tools.ietf.org
tools.ietf.org
In the IETF, we use this as a variety of voice vote. However, we don't take formal decisions using it; we use it to get a "sense of the room". The chair will make a statement, and say "if you agree, hum... if you disagree, hum... if you didn't express an opinion, hum...". And people hum.