Discover How Sound Travels

Put your hand on your throat and say "ahhh." Did you feel it buzzing? That buzz is a vibration — a back-and-forth movement — and vibration is the starting point of every sound you have ever heard.

Step 1 — Vibration creates sound

• When an object vibrates (shakes back and forth very quickly), it pushes the air particles around it.
• A drum vibrates when you hit it. A guitar string vibrates when you pluck it. Your vocal cords vibrate when you speak.

Step 2 — Sound travels through a medium

• The vibrating object pushes air particles into each other in a wave pattern — a sound wave.
• Sound needs a medium (a material) to travel through — it can move through air, water, and solid objects.
• Sound cannot travel through empty space (a vacuum) — there are no particles to push.

Step 3 — The ear receives the sound

• Sound waves enter the ear canal and make the eardrum vibrate.
• Tiny bones inside the ear pass the vibrations deeper into the ear.

Step 4 — The brain interprets the sound

• Nerve signals from the ear travel to the brain, which interprets them as a specific sound — a voice, music, or a warning.

Pitch and volume

• Pitch — how high or low a sound is. A whistle has a high pitch. A drum has a low pitch. Fast vibrations make a high pitch; slow vibrations make a low pitch.
• Volume — how loud or soft a sound is. A shout is loud (high volume). A whisper is soft (low volume). Bigger vibrations make a louder sound.