How is the "hmmm" on SE to be interpreted? [duplicate]

Solution 1:

hmm

representative of a sound made during contemplation or showing mild disapproval, attested from 1868, but this is probably a variation of the hum attested in similar senses from 1590s. etymonline

But a hmm can of course be devoid of any disapproval. I say I just called her and she isn't at home, and you reply Hmm, that's odd. I think you have to infer any disapproval or irony on a case-by-case basis.

Solution 2:

hmm

is a quasi-word, that is, it is not an acceptable formal word but is a common recognizable utterance in informal circumstances that isn't usually labeled as 'word' (though as you can see it does have an entry in a dictionary).

It has some recognizable meanings given there, but unfortunately those meanings are very slippery. Sometimes clearing your throat is done to, well, clear your throat, and other times it is for attention. As for the breathy 'hmm', it can be just a pause, or an acknowledgement of someone else's declarative statement that is neither yes nor no.

That is its semantic content but it can have a huge number of nuances variations due to pragmatics. It can be sarcastic, like a half sized snort. It can be a minor recognition, or a British understated put-down.

This is all to say that there are a few primary meanings of the 'word', but many possible interpretations.

Written or spoken, in the end it is very vague.