According to Livescience, an unvoiced laugh (with very little sound) is usually a forced reaction to a social situation. Let’s say you’re at a work meeting and a client makes a joke that you don’t find very funny, but you know you need to react. An unvoiced laugh “is more of a conscious expression. We make these panting, grunting, snorting noises when we are trying on purpose to laugh, usually for a social purpose, such as to ease conversation or make friends.” This kind of laughter is also known as etiquette laughter, and it usually implies that you are eager to get along with others.
