- 3

- 0

**1. Homework Statement**

A single sound source produces 105 dB at a distance of 5.0 m. How far away must the observer be to not hear this sound at all?

**2. Homework Equations**

**3. The Attempt at a Solution**

The reference intensity I

_{0}is the lowest intensity a human can hear, 1 x 10

^{-12}W/m

^{2}, so when the source is far enough away its intensity will be equal to this. The intensity of a sound falls off as 1/d

^{2}, so after substituting the information in the problem the equation above can be rewritten as follows:

In this equation, d

_{0}represents the distance to the sound source that produces the reference intensity and d is the distance to the original source, 5.0 m for this problem.

When this is solved for d

_{0}, the result is 177828d, or about 890 km. This can't be right! What happened? Thanks in advance for your help.