Chapter 15, Problem 39A

(a)

To determine

To calculate: The decrease in decibels provided by the ear protectors.

Answer to Problem 39A

The decrease in decibels provided = $\underset{\_}{40\text{ dB}}$ .

Explanation of Solution

Given:

Sound level Adam experiences before wearing ear protectors = $150\text{ dB}$

The ear protectors reduce the sound level to that of a typical rock concert.

Calculation:

Sound level of a rock concert = $110\text{ dB}$

As Adam was experiencing $150\text{ dB}$ of sound level before wearing the ear protectors and a sound level of $110\text{ dB}$ after wearing the ear protectors,

The decrease in $\text{dB}$ provided = $150\text{ dB}-110\text{ dB}=40\text{ dB}$

Conclusion:

The decrease in decibels provided = $\underset{\_}{40\text{ dB}}$ .

(b)

To determine

To calculate: The sound level experienced by a person not wearing ear protectors when Adam hears a barely audible whisper.

Answer to Problem 39A

Sound level a person not wearing ear protectors will hear = $\underset{\_}{50\text{ dB}}$

Explanation of Solution

Given:

Adam hears something like a barely audible whisper.

Calculation:

Sound level of a barely audible whisper = $10\text{ dB}$

As calculated in subpart a, the decrease in $\text{dB}$ provided = $40\text{ dB}$

Adam will hear $40\text{ dB}$ less than a person not wearing ear protectors. As Adam now hears $10\text{ dB}$ , and $50\text{ dB}-40\text{ dB}=10\text{ dB}$ ,

Therefore, a person not wearing ear protectors will experience $50\text{ dB}$ .

Conclusion:

Sound level a person not wearing ear protectors will hear = $\underset{\_}{50\text{ dB}}$