Along with my video, there is another good one by the author. To strengthen the lesson, here is a TUTORIAL to work through, this INTERACTIVE FIGURE showing a moving vibration source, and this INTERACTIVE FIGURE on sound.
Source: Hewitt, P. G. (2015). Conceptual Physics (12th ed.). Boston, MA: Pearson.
Source: HEWITT, P. G. (2015). CONCEPTUAL PHYSICS (12TH ED.). BOSTON, MA: PEARSON.