There is the whole theory of the right to quiet enjoyment of one's property. Most cities and counties follow this notion and if there is music, television, loud yelling, etc., the police will make the courtesy contact and explain it to the offenders. To broadcast publicly requires a permit for the noise. Do these children have a permit to have daily concerts? If you are annoyed by it, trust me, everyone else in the neighborhood is too. There is only one thing worse than a beginner wind instrument player, it's multiple beginning wind instrument players.
The morning to evening noise ordinances usually have more to do with incidental noise, such as construction, yard equipment, etc., not playing the radio, television (or musical instruments) too loud. Since this would probably be rememdied by their practice indoors, if they don't cooperate then they obviously are asses.
Shoshana (whose mother would only let her practice flute before mom got home from work....)