Sound Waves

Vibrations, pitch, and volume

Sound is a mechanical wave caused by vibrations. When an object vibrates (like a guitar string or vocal cords), it pushes and pulls on the surrounding air molecules, creating compressions (dense regions) and rarefactions (sparse regions) that travel outward as a sound wave. Frequency (measured in Hertz, Hz) determines pitch — more vibrations per second = higher pitch. Amplitude determines loudness — bigger vibrations = louder sound. Sound needs matter (air, water, solid) to travel — it cannot travel through a vacuum. Sound travels fastest through solids (about 5000 m/s in steel) and slowest through gases (343 m/s in air).