What was the distance from which the adhan could be heard in the time of the Prophet?

Question:
The call to prayer in this era is heard from very long distances by means of microphones. So, what was the distance from which the adhan could be heard in the time of the Messenger of Allah (peace and blessings be upon him)?

Answer:
Some scholars have mentioned that it is estimated to be one farsakh, and that the adhan, when the atmosphere is clear of thunder and things that alter the sound, such as winds, can be heard at a distance of one farsakh, which is approximately an hour and a half on foot.
If one is in the town, there is no specific limit; he must proceed to the mosques—as long as he hears the adhan—he must proceed to the mosques when the time arrives to pray with the people.
But if one is in a town and resides in its outskirts, if he hears the adhan, he walks and proceeds. If he does not hear it due to noises and movements, then if he investigates the time, he walks even before the adhan; so that he attends the congregation, and this is obligatory upon him. As for the sound of the loudspeaker; it is not considered; because it travels large distances.