Sound Properties

The picture demonstrates the Doppler effect. Choose the option of words that best complete the sentence:

As the fire truck approaches the listener, the sounds

are _________ and at a _________ frequency.

• louder, higher

• louder, lower

• quieter, higher

• quieter, lower

Jill is calling out to Jack, but from another room where she is unable to see Jack. Jill’s sound waves have to travel through the

doorway to get to Jack. What do we call this phenomenon?

• Reflection

• Diffraction

• Refraction

The picture shows how noise-canceling headphones work. What would be the best description of how these devices cancel surrounding sounds?

• The headphones send a sound wave to match the frequency and amplitude of the external

  sound wave causing destructive interference

• The headphones send a sound wave to match the frequency and amplitude of the external sound wave causing constructive interference

Which property explains why objects sound differently when dropped on the floor?

• Beat

• Interference

• Natural frequency

• Forced vibration

Recording studios use a special foam on the walls to reduce the effect of sounds bouncing off solid walls and distorting the recording. Which property of sound waves is the foam attempting to reduce?

• Refraction

• Diffraction

• Reflection

Which of the following is represented in this picture?

• Refraction

• Diffraction

• Reflection

Which of the following explains why a beat occurs between two different tones?

• Diffraction

• Noise-canceling

• Interference

• Doppler effect

In an echo problem, what must be done before any calculation?

• The time must be divided by 2

• The speed must be divided by 2

• The distance must be multiplied by 2

• The time must be multiplied by 2

Which equation would you use to solve this problem:

Sound waves travel at approximately 340 m/s. What is the wavelength of a sound made by a tuning fork labeled 512 Hz?