There is a purpose behind each one of the dings and chimes that occur during the flight. A single ding after take off would be understood as meaning the aircraft is removing the wheels. Three dings set in sequence would mean more attention than just a single one. If the tone is high then low, it means someone in the crew is required in another section of the aircraft; where as three low chimes indicate bad turbulence is coming and all crew members should strap down their meal trolleys and retake their seats.