Sound moves in waves. It is produced when a force causes an object or substance to vibrate. This vibration is transferred through the substance in a wave.
It is produced when a force causes an object or substance to vibrate. Vibrations can occur in gasses, liquids and solids.
If you place your hand on a speaker, you’ll feel the vibrations when it’s turned on.
If you play the drums, you are transferring kinetic energy (from the sticks) into sound energy.
These sound vibrations create sound waves, which move through mediums (air or water) before reaching our ears.
We can measure volume in decibels.
Everything has a natural frequency. A natural frequency is the frequency at which the molecules in an object vibrate naturally. We can measure frequency in Hetrz (Hz).
The human ear can hear things anywhere between 20Hz - 20,000 Hz
Watch the video bellow, Notice how the sound wave bounce off the glass
The Long Range Acoustic Device or LRAD is a military weapon, which uses sound waves to injure the enemy.
Although it doesn't kill the enemy it produces a warning tone, higher than the normal human threshold of pain and can cause serious hearing damage and nausea.
The video to the left, shows how it was first used on protestors, during the G20 summit in Pittsburgh, USA in 2009.
