Elsa Efrina, Achmad Hufad, Endang Rochyadi, Asep Bayu Dani Nandiyanto, Rila Muspita , Abu Yazid Abu Bakar. Teaching Principle of Sound Intensity Using Closed-Pipe Organs That Contain Various Levels of Water for Students With Deaf and Hard Hearing. IJAST 2020, 29, 5023-5030.