I stay far from the masjid, more than a kilometer away. Myself and my brother made an experiment whereby my brother started calling Adhan from the house while I was at a place between the masjid and the house but I did not hear his calling thereby I was satisfied that making swalah at the masjid wasn’t compulsory for me. I was then advised to ask. What is your opinion knowing that (in the experiment we did) the calling was in the night and the place I tried to listen to the calling from was almost between the house and the masjid and also my brother shouted? May you please tell me if it is wajib (compulsory) or nafil (supererogatory)? هل يجب الصلاة في المسجد؟

Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions.
Wa alaikum assalam wa rahmatullahi wa barakatuh.
As to what follows:
With regards to answering your question we say, success is by Allah Almighty.
If the Adhan cannot reach him except by loudspeakers then it is not compulsory upon him to make swalah at the masjid but it should be noted that what must be taken into consideration is that replying to the Adhan is only compulsory on the Muadhin’s normal voice which is not heard through loudspeakers or blocked by noises or electricity that we know which is in the cities due to cars, electricity and the like.
If the Muadhin shouts without using a loudspeaker and there is no obstruction and you still don’t hear the Adhan then it is not compulsory for you to perform swalah at the masjid because when blind man sought permission to leave congregational prayer, The Prophet (peace be on him) said to him: Do you hear the Adhan? He replied in the affirmative. The Prophet (peace be on him) then directed him to respond to it.

Your brother,
Dr. Khalid al-Muslih
29 / 1 / 1429 AH