Waves and Sound

amplitude

the maximum movement up or down from the rest position. Indicates the amount of energy carried by the wave.

compression

a space in a wave where there are lots of particles.

constructive interference

when waves combine in such a way that the amplitude of the resulting wave is greater than either of the original waves - occurs when waves meet crest to crest or trough to trough.

crest

highest point of the wave; it is the maximum upward displacement of the particles in a medium.

destructive interference

when waves combine in such a way that the resulting wave is smaller or less that either wave alone.

diffraction

the bending of waves around a barrier or through an opening.

Doppler effect

the apparent change in the frequency of a sound caused by the motion of either the listener of the source of the sound.

ear

the organ of the body that detects sound.

elasticity

how easily particles return to their original positions after they have been disturbed.

electromagnetic wave

waves that do not need a medium to be transmitted; these waves can be transmitted through a vacuum and can exist with or with out a medium.

frequency

The number of complete waves or cycles per unit of time. Every complete wave has one trough and one crest.

infrasonic

describes sounds with frequencies lower than 20 Hz.

intensity

the amount of energy carried by a wave; indicated by the amplitude of the wave.

interference

when two or more waves arrive at the same place at the same time. They combine to produce a single wave.

longitudinal wave

the motion of the medium is parallel to the direction of the wave; a wave that consists of a series of compressions and rarefactions.

mechanical wave

wave that requires a medium in order to be transmitted.

medium

the matter or substance through which a wave is transmitted - includes all phases of matter.

music

having a pleasing quality (timbre), a definite identifiable pitch, and a repeated timing called rhythm.

noise

any undesired sound, especially nonmusical sound, that includes a random mix of pitches.

pitch

how high or low a sound is perceived to be.

rarefaction

a space in a wave where there are fewer particles.

reflection

the bouncing back of wave after it strikes a boundary that does not absorb the waves energy.

refraction

the bending of waves due to a change in its speed.

resonant frequency

frequency at which a standing wave occurs.

sound

energy produced by an object's vibrations.

standing wave

a wave that does not appear to be moving.

supersonic

speeds faster than the speed of sound.

surface wave

a combination of two different types of waves; occur at the surface between two different mediums.

transverse wave

a wave in which the motion of the medium is at right angles to the direction of the wave. Wave moves up and down, while the medium moves left to right.

trough

lowest point of a wave. It is the maximum downward displacement of the particles in a medium.

ultrasonic

sounds with frequencies higher than 20,000 Hz.

vibration

any movement that follows the same path repeatedly.

wave

disturbance that transfers energy through matter or space. A traveling disturbance that carries energy from one place to another.

wavelength

the distance between two consecutive crests or troughs of a wave. It is measured in meters and represented by the Greek symbol lambda.