Pressure waves produced when an object vibrates at a frequency between 20 Hz and 20000 Hz and there is a material medium that sound can travel through.
Loudness: How loud or soft a sound is; loudness is related to the amount of energy that reaches our ears per unit of time.
Pitch: How high or low a sound is; pitch is related to the frequency of the vibration that produces the sound.
Timbre: Quality of a sound that makes it different from other sounds of the same pitch and loudness; timbre is related to the shape of the sound wave.
Echo: Reflection of sound from a surface that is more than 17 m away from the emitter.
Reverberation: Reflection of sound on a surface that is less than 17 m away from the emitter.
Vibration: Mechanical oscillation; movement of an object around a central position of equilibrium.
Oscillation: Repeated variation around a central position of equilibrium, first in one direction and then in the other.
Compression: Increase in air pressure that forms part of a sound wave.
Rarefaction: Decrease in air pressure that forms part of a sound wave.
Electrical Impulse: Signal carried by the nervous system.
Propagate: Multiply or increase, spread to a larger area.
Disturbance: Change in normal conditions.
Homogeneous: Uniform in composition; all parts have the same properties.
Hearing Threshold: Minimum loudness at which we can hear sounds.
Pain Threshold: Loudness at which sound becomes intolerable for the listener.
Attenuate: Decrease the intensity of something.
Pollution: Contamination of the environment, often caused by human activity.
Silencer: Part of a machine designed to muffle sound emissions.