A sound wave is an example of a longitudinal wave. Sound waves travel by compressions and rarefactions of air particles. The photo shows how a vibrating drum forms compressions and rarefactions in the air around it.
A sound wave is a longitudinal wave caused by vibrations and carried through a substance. The particles of the substance, such as air particles, vibrate back and forth along the path that the sound wave travels. Sound is transmitted through the vibrations and collisions of the particles.
All sound waves require a medium (plural, media).
A medium is a substance through which a wave can travel. Most of the sounds that you hear travel through air at least part of the time. But sound waves can also travel through other materials, such as water, glass, and metal.
Frequency and pitch
How low or high a sound seems to be is the pitch of that sound.
The number of vibrations per second is known as frequency.
The faster the vibration of the source, the higher is the frequency and the higher is the pitch.
Amplitude and loudness
Loudness is a measure of how well a sound can be heard.
The amplitude of a wave is the largest distance the particles in
a wave vibrate from their rest positions.
The larger the amplitude, the louder the sound. And the smaller
the amplitude, the softer the sound.
