When is prostration obligatory upon reciting the Qur'an, and what should a listener do if he hears a verse containing a prostration, and is it permissible to listen to the Qur'an while sleeping?

The prostration of recitation (sujud al-tilawah) is supererogatory (mustahabb), not obligatory. It is prescribed immediately upon reciting the verse or listening to it directly from the reciter. However, listening to it from a recording device does not warrant prostration, because the listener only prostrates if the reciter prostrates. As for the verse, "When the verses of the Most Merciful were recited to them, they fell in prostration and weeping" (19:58), it is a commendation of the prophets and those whom Allah guided, due to their perfect fear and submission to Allah. Weeping is recommended when reciting or listening to the Quran.