Ok, this is going to be really hard to explain, but here goes... Essentially, in some scenes in my planned novel, I envision characters doing this thing. It's where you snort, but not like a pig, you make a "huh" noise, though you don't use your mouth, it's more of an inhalation of air through your nose. It's something you do when you find something vaguely funny or amusing, or you're appreciating some wit. It's not funny enough to make you laugh, but you're like "heh". So, what's it called? Is there a name for it? Saying "Bob sort of laughed, sort of snorted", doesn't really work well.