Answered by Shaykh Faraz Rabbani
You mentioned in your questions and answers: The laughter of an aware adult person in a prayer that contains bowing and prostration, even for the one praying by head motions alone. You said that it is invalidated. Wudhu. Dies that mean that if an adult laughs in salaatul janaazah then his prayer is still valid. Does it make a difference if he laughs quietly or loudly?
Walaikum assalam wa rahmatullah,
If one laughs audibly (even if only to oneself) in the funeral prayer or prostrations of recital, these are invalidated, though one’s wudu itself remains valid. [Maraqi al-Falah, Durr al-Mukhtar Sharh Tanwir al-Absar]
It is, of course, normally the sign of a heart in trouble for one to laugh at a funeral prayer.