Underlaugh

John Joy Tree greeted this with an ugly underlaugh, a barely audible sound which made Casher feel the whole situation was ridiculous.

Source: wiktionary

“A stretcher case, surely,” he added, and an underlaugh rippled through the ranks and files.

Source: wiktionary

So in this specific role, in this specific scene, my fontal rush of propulsive fear, my prickly self-strickenness, and my strangled underlaugh that was (and still is) a result of what Sigmund Freud identified as the “liminal dilemma between the intense desire for supplication and the concurrent need for masochistic provocation” all combined to create an illusion of a brilliant stage presence, bursting with potential and future possibility.

Source: wiktionary

Campbell laughed a quiet under-laugh, half sad, half humorous.

Source: wiktionary