People often think that a rooster's crow is louder than it actually is. Many people complaining about roosters having a noisy crowing are likely more upset because they're woken up early. The intermittent nature of the sound might also bother some people. Nevertheless, a rooster's crowing only tops 90 decibels (similar to the sound of a barking dog). Chickens clucking and carrying on with ...
First, are you sure that it is a rooster? Some roosters start crowing early, while others don't crow for months. I've had some start at 6 weeks, while others have waited until about 4 months old. If you have other roosters, a submissive rooster usually doesn't crow much/at all be cause it is subordinate and doesn't want to arouse the dominant one.
A rooster's crow is around the 130 decibels range. A hen's cluck is around the 60 decibel range. Of course how close you are to the sound makes a difference in how loud it sounds, (which is why people who own roosters don't go deaf- most are not in close range of the crow), but prolonged exposure is more dangerous than shorter exposure.
Roosters crowing only in the morning is really just the movies. It is one of the common misconceptions about roosters. In reality roosters crow all the time. There is nothing wrong. The behavior is normal. It is why they are illegal in a lot of cities.
Some roosters just like to crow. But in my experience the younger roosters crow forever, like they discovered their voice and want the whole world to know. Then my older roosters know to only crow in the mornings or to warn of danger.