Sound is produced when things vibrate, or shake. A vibrating object makes the air next to it vibrate as well. These vibrations travel through the air as a sound wave, which we hear with our ears. Sound waves can also travel through liquids and solids, such as water, rock, or wood.
Making sound
When the climber hits the metal spike with his hammer, it vibrates. This vibration causes the surrounding air to vibrate too, producing a sound wave.
Sound wave
The sound wave spreads out through the air. It travels away from the rock and hammer until it reaches a solid surface.
Reflection
When the sound wave hits a solid surface, such as the side of a cliff, some of the energy becomes back towards the climber. The rest of the sound energy travels through the rock.
Echo
The climber will hear the reflected sound wave as an echo, a few moments after he first produced the sound.
Picture Credit : Google
