1-9 Intensity of Sound Waves

* Try This At Home Experiment:

Play the following audio link through your computer speakers. As you listen to the music clip slowly walk away from the computer. As you walk away is the sound getting louder or softer? Pink Panther Theme Audio

You should see that as you travel farther from the source of sound, the volume of the sound is decreasing. Why do you think this is?

Power

As a source (the instrument) vibrates, it transfers energy to the medium (in this case air) and this energy passes through the air in the form of a sound wave. This is called acoustical energy.

The rate at which energy is radiated from an instrument is that instrument's power output.

Power can be found with the following formula:

    Power = energy/ time

The unit of power is the watt.

The farther away you are from the source of the sound, the less power there will be (making the volume softer).

Intensity

In the opening experiment we noticed that the closer we are to a source the louder it will be. This sensation of loudness is known as the intensity of the sound wave.

Intensity can be found with the following formula:

    Intensity = power / area

The unit of intensity is W/m squared

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