Is it allowed to play Qur'an in the backround while one is performing salat?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If the Quran is played aloud in a way that it disturbs the praying people or the people reciting silently in anyway, then doing it is unlawful as it harms them and prevents their hearts from concentrating on the meaning during the reading or while praying. Ahmad and Malik reported from Al Bayadhi that the Prophet once went out (of his house) to the people (in the mosque) and found them praying and reading with loud voices, so he said: “The praying person is talking to his Lord The Almighty. So, he should know what he is saying and none of you should make his voice louder than the other one while reciting the Quran.”

Al-Baji said while explaining this, that none should make his voice louder than the person next to him, as this might cause mutual harm, preventing concentration in prayer and from understanding the meaning of what one is saying.

Therefore, playing the Quran loudly in such situation is unlawful. Talking loudly and making similar sounds is more unlawful as it harms the praying people.

Allah knows best.