Listening to recitation is the perfume of the souls, the calmer of hearts, and the food of the spirit. Is is one of the most important psychological medicines. It is a source of pleasure, even to some animals – and pleasure in moderation purifies inner energy, enhances the functioning of the faculties, slows down senile decay by driving out its diseases, improves the complexion, and refreshes the entire body. Pleasure in excess, on the other hand, makes the illnesses of the body grow worse.
Abu Nu’aim states, in his Tib an-Nabbi, that the Prophet (صلى الله عليه وسلم) said that the benefits of listening to recitation are increased when it is understood – that is, when its meaning is understood. Allah Himself says:
…so give good news to My slaves, those who listen to the word and then follow the best of it…(Qur’an: 39.17-18)
Source: As-Suyuti’s Medicine of the Prophet (صلى الله عليه وسلم)