Yes, it works quite well to get a sense of the room. The advantage of humming is that people can change the volume to match their level of agreement with the question being asked. If they strongly agree with the question, they can hum very loudly. If they only weakly support it, they can hum quietly. The chairs of thesession can then get an audible sense of the level of agreement (or not).
Often in the sessions I've been in, there may be two hums taken - one for those in support of a question, and one for those opposed. Often there can be a clear distinction - but sometimes the results can be inconclusive if both sides seem to have equal volume. (But that, too, is helpful to the chairs as they can get a sense that the people in the room are divided.)
We used to use a show of hands (raised hands). However, participants with limited sight could not get a sense for the state of a room when a show of hands was called for. So we switched to humming. Now, you might wonder how that works for people who are hard of hearing, but oddly enough that has not come up as much.
If ever we have to, we could do both, and then still call it "humming" since it would still be that and it's a very pithy (two syllables) word for it.
It's also possible that humming has little to do with sight and more to do with using the volume of humming to help indicate the strength of the sense of the room -- that actually is a very useful aspect of humming. However, humming became a thing concommitantly with participation by people with limited sight, which is probably why I remember that as a motivation, but in fact it might not have been! It's been a long time now that the IETF uses humming...
It sounds like a less wordy, more vague version (as you can't visibly tell who exactly is humming) of the "aye"/"nay" voice voting.