Sound Waves

Wave

a disturbance that carries energy

Medium

a substance through which a wave can travel; matter

longitudinal waves

the particles of the medium vibrate along the path that the wave takes; requires a medium to move through

compressional wave

also known as a longitudinal wave

compression

the area in a longitudinal wave where the particles are pressed closely together.

Rarefaction

the area in the longitudinal wave where the particles are spread apart.

Reflection

when a wave bounces back after striking a surface

Refraction

the bending of light as it passes, at an angle, from medium to another

Diffraction

the bending of waves around a barrier or through an opening. For instance hearing a person around a corner before seeing them.

Interference

the result when two or more waves overlap.

constructive interference

when a crest of one wave and the crest of another wave overlap. Creates a larger amplitude

Destructive interference

when a crest of one wave and a trough of another wave overlap, results in a smaller (or no) amplitude.

Resonance

When the vibration of an object causes a second object to vibrate at the same frequency. For instance, when a piano playing causes the water in a glass nearby to vibrate at the same frequency.

Tacoma Narrows Bridge

A bridge destroyed on 11/7/1940 caused, in part, by resonance. The wind blowing across the bridge caused vibrations to move through the bridge at its resonant frequency. These waves interfered with each other (constructively) and caused a large build up in energy until the bridge began to twist and then collapse.

Wave Speed

the rate at which the sound wave moves, depends on the density (type) of the medium and the temperature of the medium. Speed increases when density and/or temperature increases.

Ultrasonic waves

sound waves with a frequency above 20,000 Hz, outside the range of normal human hearing.

Amplitude

The wave height, also a measure of loudness of a sound. The larger the amplitude, the louder the sound.

Echolocation

The use of sound waves reflections (echo) by animals to locate objects.

SONAR

SOund Navigation And Ranging. The human form of echolocation. Used by the navy, oceanographers, and fisherman. Ultrasonic waves are used and a machine monitors the echo to determine what objects are around and the distance those objects are from the source/boat.

Ultrasounds

the use of ultrasonic waves to see inside the body without performing surgery. This is used to see babies inside the womb as well as internal organs.

Sound Energy

The energy from an object vibrating.