Some posts should be read and re-read again by some of the posters here. This I think belongs to that category. Religion is a very private matter and I really do not know if God is being forced to hear some of the prayers.
In a time wherein there are any number of means to be reminded for the time for prayer, I think it is surprising that we still need loudspeakers.
People who want to pray will find a way to get reminded, while people who do not want to pray would not pray if you have the loudest speakers..