Sound Type / Sound Source/(声音种类/音源) -> #1of3 Beginner/(初学) -> Properties of Sounds/(声音的属性) -> Learn/(学习)

Sound Type / Sound Source/(声音种类/音源) -> Modes of Listening/(聆听模式) -> Theory/(理论) -> Step 2 High School/(第二步高中) -> Years Group/(年级群)

Sound Type / Sound Source/(声音种类/音源) -> Properties of Sounds/(声音的属性) -> #1of3 Beginner/(初学) -> #[Tier 6] Pedagogical Aspects for Children/([第六]教育层为儿童) -> Users Group/(用户群)