Sound Review

A couple attends an outdoor symphony in July and again in December. During the second performance, they both notice a delay in the sound, which gives the impression that they are listening to a recording rather than a live performance. What principle of the speed of sound best explains their observations?

• The speed of a sound wave varies with its wavelength and frequency.

• The speed of a sound wave depends upon the temperature of its medium.

• The speed of a sound wave is affected by the stat of matter of the medium.

• The speed of a sound wave changes depending on the density of the particles in the medium.

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Which of the following is the best example of resonance?

• a bat uses ultrasonic waves to locate its next meal

• a telephone changes sound waves into electric signals

• a guitar body vibrates from the sound of a plucked string

• a jet produces a sonic boom as it breaks the sound barrier

Which of the following is the best example of resonance?

• A singer holds a high-pitched note, causing a crystal glass to vibrate until it shatters.

• Sound waves directed into a cave strike the cave's rear wall, reflecting back to their source

• A doctor sends ultrasonic waves into a person's body, producing an image of the person's internal organs.

• Two sound waves of nearly equal frequency interfere, producing an alternating pattern of loud and soft sounds.

What role does the inner ear play in hearing?

• Captures sound waves

• transmits sound waves from air to fluids

• converts sound waves into electrical signals

• removes high and low sound waves that are harmful

What role does the outer ear play in hearing?

• captures sound waves

• transmits sound waves from air to fluid

• converts sound saves into electrical signals

• removes high and low sound waves that are harmful

Which of the following accurately describes a difference between and audio CD and a digital file?

• Sounds can be stored on an audio CD but not in a digital file

• Unlike a digital file, and audio CD does not require a computer to record and play back sound.

• An audio CD stores sounds as pits on the CD's surface, whereas a digital CD stores sounds as a computer code

• Unlike the information stored on an audio CD, the information stored in a digital file can be converted into sound waves.

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The vibrating string shown produces a sound. If the same string produced a louder sound, how would the string's appearance change?

• The string would vibrate to a lower height.

• The string would vibrate to a higher height.

• The string would vibrate over a longer distance.

• The string would vibrate over a shorter distance.

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Two police cars are driving down the highway at 80km/h in pursuit of a car thief. The first car turns on its siren, which has a frequency of 650 Hz. What frequency will the police officer in the second car hear?

• 650 Hz

• less than 650 Hz

• greater than 650 Hz

• There is not enough information to answer this question.

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For what purposes do bats use ultrasonic waves?

• sonar

• ultrasound

• echolocation

• Doppler effects

Which of the following best explains how a microphone works in a telephone.

• The microphone increases the volume of the incoming sound

• The microphone transfers electrical signals from the wall to the phone

• The microphone converts incoming sound waves into electrical signals

• The microphone converts incoming electrical signals into sound waves