Sound waves travel by alternately compressing and ______.

• expanding
• sound
• vibration
• sound waves
• vacuum

_____________ causes sound

• vibration
• sound
• sound waves
• vacuum
• supersonic

_____________ is a periodic back and forth motion of the particles of an elastic body or medium.

• vibration
• sound
• sound waves
• vacuum
• supersonic

If something travels faster than the speed of sound it is called __________________

• supersonic
• sound
• vibration
• sound waves
• vacuum

The loudness of a sound is measured in a logarithmic unit called ________

• decibel
• sound
• vibration
• sound waves
• vacuum

How high or low a sound depends on its ___________

• frequency
• pitch
• sound
• vibration
• sound waves

The rate at which something occurs or is repeated over a particular period of time in a given sample is called its ____________

• frequency
• sound
• vibration
• sound waves
• vacuum

When sound waves are reflected back to its source (so we hear it again), it is called an ____.

• echo
• sound
• vibration
• sound waves
• vacuum

The pitch of a sound is measured in _______ (which is the SI unit of frequency).

• hertz
• sound
• vibration
• sound waves
• vacuum

The three types of musical instruments are percussion, stringed, and ________.

• wind
• sound
• vibration
• sound waves
• vacuum