My father is 89 years old, Indian origin moved to USA in 1980's. My mother has died in 1983 and since than my father had stayed with me, my brothers, sisters and finally he decided to stay alone. For a year and half he was happy staying alone. Recently he has severe arthritis of knees and cannot walk and has become wheel-chair dependant. By brothers made changes in the house to accommodate the wheel-chair. He refused to stay with any of his kids - did not want to create more problems in his children's family life. All of us pitch to do routine house-hold chores for him and most of the day and nights he is alone. He lives in a 2 bed room house all by himself.
He spent most of the time studying and reading Qur'an. My father's health except for arthritis and blood pressure is fine. He is mentally very sound and Masaha Allaah, has very good memory and intelligence.
From past 2 months he is hearing unknown male voices reading Qur'an - Tilawat of Qur'an - at first he used to hear it at night, now he hears it all day, night and at night he hears even the Salaam.
He has been reading Qur'an, Ayattul-Kursi, Manzil and every day. He is not afraid but he is not getting enough sleep and he does not know why he is hearing it. Doctors' don't understand it - they think he has dementia -Alzheimer's dementia.
He is not demented - there is no change in him no change in behavior, no change in memory, he has good attention, good concentration &still does every thing as he used to all his life. No change at all.
I am writing on behalf of my father - he wants to know (1) whether there is Jinn in the house or (2) he has being overpowered by a Jinn - perhaps good Jinn as he only hears Qur'an and Salaam
(3) My father wants to know whether there is any special Du'a to get rid of Jinns even a good Jinn. If you can respond to this as early as possible - he is impatient to hear the answer from a Mukthi.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

The recitation of the Qur'an and the Salaam that your father hears could be from Jinn who inhabited the house. The Prophet said: "Indeed these homes are inhabited." These inhabitants could be Muslims or non-Muslims. It appears from the question that this Jinn is a Muslim but he does not know that it is not permissible for him to recite the Qur'an and say Salaam in this way.

It could also be due to your father's advanced age, as this is a common thing with people in his age. In any case, we advise your father to warn the Jinn to get out of his home. It is confirmed by Al-Bukhari and Muslim that the Prophet said: "Verily these homes are haunted by Jinn, so if you see anyone of them, warn him three times [or could mean for three days] that he is not welcome and harm and embarrassment will be caused to him if he stays or appears to you, then if he leaves, all the best, otherwise kill him for he is a Kafir (non-Muslim)."

If after repeating the warning three times or for three days, the Jinn still remains in the house, then your father can seek the help of some scholars and pious people who treat persons possessed by Jinn in order to drive the Jinn out of the house. This is of course if we suppose that it is really a Jinn who inhabited the house, and this is a weak hypothesis. Anyway we advise the sister asking the question not to leave her father alone, living alone and spending the night alone. It is confirmed that the Prophet said: "If the people knew what I know about traveling alone, then nobody would travel alone at night." [Al-Bukhari]  He also said: "If the people were aware of the dangers of being alone, no person would dare to stay alone." [Ahmad] Therefore, try to convince your father to live with you as this is better for his religion and worldly matters.  

Allaah knows best.