The Call to Prayer rang out frequently during our stay. We would hear it first from our hotel room at 6:00 a.m, but by our third day we took it so for granted as to find the sound barely noticeable even though there was a mosque close enough to our hotel that we felt we could reach out and almost touch the minaret from which the call rang.
As a rule business is so pressing in downtown Istanbul that even prayerful Muslims stop reverently for a moment at the call to prayer rather than rush to the nearest mosque, at least during an ordinary day.
Here is a food stand we passed as we heard the call to prayer and a pastry shop from which we heard it as well. The tasty food did not hinder our own moment of reverence.