It must reflect off the surface of an object
to produce an echo, the sound wave bounces off a surface and then comes back
Reflection
An echo of a wave is exactly the same type of wave as the original wave. An echo is simply the original wave returning to the observer, so if you made a sound (a longitudinal wave of vibrating air molecules), the echo is also sound waves.
When a sound wave is reflected, you hear an echo.
An echo.
to produce an echo, the sound wave bounces off a surface and then comes back
An Echo-echo-echo-echo! The answer is Echo
The result of a reflected sound wave is obviously an echo.
An echo is a sound wave that has bounced off a surface
Reflection
An echo of a wave is exactly the same type of wave as the original wave. An echo is simply the original wave returning to the observer, so if you made a sound (a longitudinal wave of vibrating air molecules), the echo is also sound waves.
A standing wave?
When a sound wave is reflected, you hear an echo.
A wave reflection.
An echo.
I am guessing a sound wave.
No, an echo is a reflected sound wave and does not have the ability to speak or produce independent sounds. It simply repeats sounds that are made in its vicinity.