The term Canyons Sound Effect is composed of two crossword solutions, ECHO (4 letters) and Pow (3 letters). ECHO is a sound that is heard again after it is produced, usually due to reflection off a surface. It is often associated with canyons and other large, open spaces. Pow is an onomatopoeia that is used to describe a loud, explosive sound, such as an explosion or a gunshot. It is also commonly used to describe the sound of thunder. Together, these two words describe the sound effects that are often heard in canyons, such as echoes and loud noises.