Most local noise ordinances designate certain "quiet hours" -- for example, from 10 p.m. to 7 a.m. on weekdays and until 8 or 9 a.m. on weekends. So running a power mower may be perfectly acceptable at 10 a.m. on Saturday, but not at 7 a.m. Some universally disturbing sounds are commonly banned or restricted. For instance, most cities prohibit honking car horns unless there is danger. This means that the daily early morning tooting across the street for the carpool is a violation. Dogs and motorcycles may also be singled out.
Many towns also prohibit sustained noise that exceeds a certain decibel level. The decibel limits are set according to the time of day and the neighborhood zoning. When a neighbor complains, police place decibel level monitoring equipment on an estimated property line and take a reading