Someone who is cheerful will speak in a moderately loud, moderately high pitched voice, at a moderately fast rate, with more rising than falling intonation. In more extreme cases of true joy, the moderation disappears: the speaker is loud, high-pitched, fast, and has mostly upward intonation.
A genuinely happy (involuntary) smile includes not just raising the corners of the lips significantly (with mouth open, though the teeth may be showing or not), but also contraction of the muscles around the eyes, often resulting in “squinting” and “laugh lines” (sometimes referred to as “crows’ feet”).
Genuine laughs also indicate happiness. In some cases of intense joy, people may laugh uncontrollably, weep, clap or dance.
The following photos were all captured from friendly conversations, where the participants were not consciously aware that they were modeling happiness.
Note the difference in intensity. His posture is relaxed (shoulders down) and his body language is open in both. The closed-mouth smile is somewhat happy, while the open-mouth (with or without genuine laughter) comes across as much happier.
Obviously, the young woman is very happy. The fellow in back is not emoting as dramatically, but his lips are curved slightly upward — he looks mildly happy, but not nearly as happy as in the 2nd photo. Even with the glasses, you can see the ‘laugh lines’ by his squinting eyes.
This pair isn’t intended to indicate different intensity levels (she’s very happy in both). Notice that she maintains an open-mouthed smile even while speaking, but of course the smile is even bigger when she laughs.
Notice how she throws her head back to laugh. (So did the woman above, but it’s more subtle there. You have to look at the angle of her shoulder.) This change of posture is common with genuine happy laughter (as opposed to “fake” (social) laughs). Note that the happy expression not only signals her emotion but also serves as an active listening cue, since she her expression is responding to what the speaker is saying.
Two more happy faces. We’re not trying to illustrate any particular comparison here — we just enjoyed these photos.
The words tell us only that “there’s no school today,” but he’s clearly very happy about this!