CK-12-Physics - Intermediate

11.1. Transmission of Sound http://www.ck12.org

11.1 Transmission of Sound

Objectives

The student will:

• Describe how mechanical waves are transmitted.


• Explain what is meant by the superposition of waves and interference.


• Explain and evaluate sound intensity.

Vocabulary

• amplitude: The magnitude of the greatest departure from the equilibrium position or density of the wave
  disturbance.


• frequency:The number of times a specified periodic phenomenon occurs within a specified interval.


• intensity: The intensity of any wave is the time-averaged power it transfers per area through some region of
  space.


• superposition:The superposition principle, also known as superposition property, states that, for all linear
  systems, the net response at a given place and time caused by two or more stimuli is the sum of the responses
  which would have been caused by each stimulus individually.


• wave interference: A phenomenon in which two waves superimpose to form a resultant wave of greater or
  lower amplitude.
  
  
  • constructive interference: Occurs when waves are superimposed and form a wave with a larger ampli-
    tude than either of the original waves.
  
  
  • destructive interference: Occurs when waves are superimposed and form a wave with a smaller ampli-
    tude than either of the original waves.
  
  
  
  


• wavelength:The distance between one peak or crest of a wave and the next corresponding peak or crest.

Introduction

What is sound? How does sound travel from one location to another?

Sound is a wave composed of vibrations. We can feel the vibrations if we put a hand in front of a speaker playing
loud music, and we can see the vibrations if we put a cup of water in front of the speaker. If we were to look at
sound being produced very slowly, we would see the speaker push forward and compress the air in front of it. This
compressed air then presses against the regular air past it, and the compression moves forward as a wave (specifically
a longitudinalwave).