I do not hear trains and I miss it. I grew up hearing them all the time. Where I lived the longest I only heard the 3AM train in the distance. Most mornings I heard it. There are trains in South Florida but I've never seen one anywhere close to me. I cross one when I drive to my mom's.
Half-hourly during the daytime, more frequently during peak commuter times. I'm on one in the morning, another in the evening - we're about a half mile from the Gawler Central line.
Growing up we lived 2 blocks away from the tracks. I did not even notice the noise then. As an adult going back home to visit the noise was very annoying.
The closest railway station is about a mile away. Occasionally, I hear the train whistle, but it's rare. Like Zach, I live on a very heavily-traveled street with a fire house, hospital and police station nearby, so there's plenty of noise from cars, trucks and sirens.