12-1	概述 Overview
12-2	聲波的速度與波前的介紹 Velocity of Sound Wave and Introduction of Wave Front
12-3	駐波 - Closed and open pipes Standing Wave - Closed and open pipes
12-4	都卜勒效應 Doppler Effect
12-5	波的干涉與拍 (Beats) Interference of Waves and Beats
12-6	聲波的波動方程式 Wave Equation of Sound Wave
12-7	聲波能量的傳遞、Intensity、Intensity Level Sound Energy －Transmission, Intensity, Intensity Level