Hears Azan whilst reading Quran
In the name of Allah, the most Beneficent, the most Merciful.
It is mustuhub to respond to the azan and doing so holds great reward. It is mentioned in a hadith that the Prophet of Allah Sallallahu Alahi Wasalam said, “Whoever repeats the words of the muadhin with conviction will enter Paradise.” (Sahih Muslim p.167 v.1)
With regards to your question, if one is reciting the Quran and the muadhin calls the azan, it is preferable to close the Quran and reply to the azan. However, if he continues reciting the Quran, there is no sin in it. (Raddul Muhtar p.65-p.66 v.2)
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham