This is the sound of a chime. (Japanese school bell). It's used by most of all Japanese schools. (elementary, junior high, high school, university, etc.)

This sound rings when a class starts or ends. It rings first around 9:00 AM from 8:30 AM. If you will travel to Japan, you can hear this sound near Japanese schools.

This sound is half size length of real school's chime. In the morning, many students begin running when it ringing.