Chapter 12, Problem 22P

To determine

To Find: The lowest and highest frequencies correspond to the given sound level.

Answer to Problem 22P

The lowest and highest frequencies that an ear is detected is $150\text{Hz}$ and $20,000\text{Hz}$ respectively when the sound level is $30\text{dB}$ .

Explanation of Solution

Given:

The sound level is $30\text{dB}$ .

Calculation:

The graph for sound level versus frequency is shown below.

  

At $30\text{dB}$ the low frequency threshold of hearing is about $150\text{Hz}$ , according to the given graph. On the higher frequency side, there is no intersection of the threshold of hearing with the $30\text{dB}$ level. Therefore, the $30\text{dB}$ signal can be heard up to the highest frequency that a human car hear is $20,000\text{Hz}$ .

Conclusion:

The lowest and highest frequencies are $150\text{Hz}$ and $20,000\text{Hz}$ respectively.