Transverse pulse or wave A pulse or wave in which the motion of the medium is perpendicular to the motion of the wave

Amplitude The height of a wave crest; it is related to a wave’s energy

Periodic Wave A repetitive series of pulses; a wave train in which the particles of the medium undergo periodic motion (after a set amount of time the medium returns to its starting point and begins to repeat its motion).

Standing Wave The superposition of two waves traveling in opposite directions characterized by lack of vibration at certain points, between which areas of maximum vibration occur periodically; produced whenever a wave is confined within boundaries, as in the vibrating string of a musical instrument.

Crest The highest point on a wave.

Wavelength The distance (measured in the direction of propagation) between two identical points in consecutive cycles of a wave.

Frequency The number of waves produced per unit time; the frequency is the reciprocal of the amount of time it takes for a single wavelength to pass a point.

Compressional pulse or wave A longitudinal pulse or wave caused by means of the compression of a fluid, as a sound wave in air.

Longitudinal pulse or wave A pulse or wave in which the motion of the medium is parallel to the direction of motion of the wave motion.

Trough The lowest point on a wave.

Node A spot on a standing wave where the medium is motionless.

Pitch The quality of a sound dependent primarily on the frequency of the sound waves produced by its source. Like a high or low note.

Wave The propagation of energy without the movement of mass.

Reflection The bouncing of waves off an object’s surface. In sound waves, it is called an echo.

Diffraction When sound waves bend around an object or spread out as they pass through an opening.

Constructive Interference When the crests and troughs of one wave overlap exactly with those of another. These waves are IN PHASE.

Destructive Interference When the crests of one wave overlap with the troughs of another. These waves are OUT OF PHASE.

Doppler Effect The shift in frequency when the wave source and the listener are in motion relative to each other.

Ultrasonic Describes frequencies too high for humans to hear i.e. higher than 20,000 Hz or 20 kHz. Like those made by a dog whistle or those used in ultrasounds.

Subsonic Describes frequencies too low for humans to hear i.e. lower than 20 Hz. Like rumbles from an earthquake.

Supersonic Describes any object that moves faster than the speed of sound (~340 meters/second).

Sonic Boom The shockwave felt and heard from an object breaking through the compressed air in front of it as it accelerates past the speed of sound.

Resonance When the frequency of a forced vibration or sound matches the natural frequency of an object or material resulting in the amplification of the original soundwave.

Refraction The bending of sound waves when parts of the wave travel at different speeds. Sound travels faster in warmer, still air than in colder windy air.