Question

The sound pressure level 0.75 m from a noisy motor resting on a concrete floor is measured to be 75 dB. Find the sound power and the sound power level of the source.

a. Calculate the sound power and sound power level
b. Determine the frequency of the motor
c. Measure the distance from the motor to the concrete floor
d. Assess the temperature of the environment

Answer 1

The sound power level of the noisy motor is approximately 66.2 dB and the sound power is approximately 13.98 watts.

Step-by-step explanation:

To calculate the sound power and sound power level of the noisy motor, we will use the formula:
Sound power = 10^(sound power level/10)
Given that the sound pressure level is 75 dB and the distance from the motor is 0.75 m, we can use the formula:
Sound power level = 20 log (sound pressure level/reference sound pressure level)
The reference sound pressure level is taken as 20 μPa.
Substituting the values in the formula, we get:
Sound power level = 20 log (75/20 μPa)
Sound power level = 20 log (3750)
Sound power level ≈ 66.2 dB
To find the sound power, we can use the formula:
Sound power = 10^(66.2/10)
Sound power ≈ 13.98 watts