| A | B | 
|---|
| Sound waves travel the slowest through | gases | 
| The highness or lowness of sound is called | pitch | 
| Sound travels from its source in | waves | 
| The speed at which sound travels through different states of matter depends on | how closely the object’s molecules are packed together | 
| Sound is a form of energy which is always produced by | vibrating matter | 
| heard when sound reflects off of a surface | echo | 
| The number of vibrations in a given unit of time | the frequency of sound | 
| The rapid back-and-forth motion of matter resulting in a sound wave | vibration | 
| sound can't travel through a | vacuum | 
| used to detect sounds and locate underwater objects | sonar | 
| increases as a submarine dives deeper into the ocean | water pressure | 
| crest to trough | wave length |