14.4 Human Perception of Sound

Which term applies to the following explanation? The Amount of Sound Energy passing through a given area is called:

• Decibels

• Loudness

• Area

• Intensity

A large stadium loudspeaker puts out 0.26 W of sound through a square-shaped area 1.2 m on each side. What is the intensity of this sound?

Intensity = Power / Area (*Area = side²)

• 0.12 W/m²

• 0.16 W/m²

• 0.18 W/m²

• 0.21 W/m²

What happens to the Intensity of sound the FURTHER an observer is from the sound source?

• Increase

• Decrease

• Stay the same

What area does a sound with an Intensity of 0.112 W / m² pass through if the power of the source is 0.54 W?

Intensity = Power / Area

• 4.48 m²

• 4.82 m²

• 5.12 m²

• 5.36 m²

Intensity ‘changes’ based on the proximity/distance from the source. Which of the following is TRUE?

• If one were CLOSER to the source they experience a greater intensity

• The one were FURTHER AWAY from the source they experience a lower intensity

• Both A + B are correct

• Neither A or B are correct

Perceived Loudness: A student cranks up her earbud jamming out to music from 58 to 68 decibels (increases by 10 decibels). How much more intense is the newly cranked up jam than it was prior?

• 100 times greater intensity

• 20 times greater intensity

• 10 times greater intensity

• 5 times greater intensity

Doubling the loudness corresponds to increasing the intensity by a factor of 10. Which of the following is TRUE?

• A person hearing a 50 db sound is 100 times greater intensity than a 30 db sound

• A person hearing a 60 db sound is 10 times greater intensity than a 50 db sound

• A person hearing a 70 db sound is 10 times lower intensity than a 80 db sound

• All answers are true

A crying baby emits a sound with an intensity level of 69 dB. If 10 identical babies are in a nursery together, all crying with the same intensity, what is the intensity level of the sound they produce?

• Same loudness

• Twice (2x’s) the loudness;

  10x's the intensity

• 10 times louder;

  100x's the intensity

• 100 times louder;

  1000x's the intensity

Mr. Stafford is from Iowa, our state motto is ‘More pigs than people’. In a pig-calling contest a caller produces a sound with an intensity level of 100 dB. How many such callers would be required to reach the pain level of 120 dB?

• 10 pig callers

• 20 pig callers

• 100 pig callers

• 200 pig callers