19-1 Properites of sound waves When we discuss sound waves, we normally mean longitudinal wave in the frequency range 20 Hz to 20,000 HZ, the normal range of human hearing For simplification we will consider the sound wave in 1D caseWhen we discuss sound waves, we normally mean longitudinal wave in the frequency range 20 Hz to 20,000 Hz, the normal range of human hearing. For simplification, we will consider the sound wave in 1D case. 19-1 Properites of sound waves