amplitudeHow far the air is pushed off its resting pressure. The bigger it is, the louder the sound. On a drawing of a wave it is the height of a peak above the middle line.
decibelThe unit, written dB, on sound-level meters. It is one tenth of a bel. Ten times the power adds 10 decibels, so 20 more decibels means a hundred times the power.
echoA reflected sound that arrives after the original. The farther off the reflecting surface, the longer the delay. The bottom of a well and the walls of an empty room give echoes.
frequencyThe count of vibrations in one second. It is measured in hertz. A guitar's low A string makes 110 vibrations a second, and the A an octave above it makes 220.
hertzThe unit, written Hz, that frequency is given in. It is one cycle per second, named after Heinrich Hertz. A thousand hertz is a kilohertz.
loudnessWhat the ear makes of a sound's strength. It is a judgment made by the ear and the brain, not a reading on a meter. The crack of thunder can pass 120 decibels.
Show all 36 terms (30 more)
Sound wave basics, continued
mediumWhatever a sound moves through: gas, liquid or solid. Air is the usual one, but sound also travels through water and through solids.
pitchWhere a sound falls between deep and shrill. A whistle is high-pitched and a drum beat is low. The pitch of a voice depends partly on how long the vocal cords are.
sound waveA ripple of pressure that the ear can pick up. It carries energy outward from whatever is vibrating. The air itself does not travel along with it.
speed of soundAbout 343 meters a second in room-temperature air. That is about 767 miles an hour. In freezing air it drops to about 331 meters a second.
vibrationThe to-and-fro shaking that starts every sound. Vibrare is Latin for to shake. A tuning fork, a guitar string and the cone of a loudspeaker all vibrate.
wavelengthHow far a wave travels during one vibration. It is the distance over which the wave repeats. A higher frequency means a shorter wavelength.
How sound travels 12
anechoic chamberA room built so that it gives back no echoes. The word means without echoes. Inside, a listener hears only the sound that comes straight from its source.
compressionThe squeezed, high-pressure part of a sound wave. Here the air particles are closer together than usual.
Doppler effectThe pitch change heard as a siren speeds past. The pitch is higher while the source comes closer and lower as it moves away. It is named after Christian Doppler, who described it in 1842.
echolocationA bat's way of steering by sound in the dark. The bat sends out high calls and hears what bounces back, which lets it chase tiny insects without hitting anything. Dolphins do it under water.
infrasoundSound pitched below the bottom of human hearing. That means below 20 hertz. Elephants call to one another with it over great distances.
longitudinal waveA wave that shakes matter along its line of travel. A sound wave is one: each bit of air shuffles forward and back on the line the sound is taking.
Mach numberA speed counted in multiples of sound's own speed. Mach 1 is the speed of sound itself and Mach 2 is twice that. It is named after the physicist Ernst Mach.
rarefactionThe thinned-out stretch between two compressions. Here the air particles are farther apart and the pressure is lower.
resonanceA strong vibration set off by a matching frequency. An object pushed at its own natural frequency soaks up energy and swings wider. Musical instruments depend on it.
reverberationSound lingering in a room after its source stops. Many reflections build up and then die away as surfaces, furniture and people absorb them. Reverb is the short name.
thunderA lightning bolt's shock wave, heard as a rumble. It can be a sharp crack or a long, low rumble. The flash is seen first because light is far faster than sound, so counting the seconds between the two shows how far off the lightning is.
ultrasoundSound pitched above the top of human hearing. That means above 20,000 hertz. Dogs hear up to about 45,000 hertz and bats up to 120,000.
Hearing and making sound 12
auditory nerveThe cable that takes the ear's signals to the brain. Cochlear nerve is another name.
beatA slow throb heard when two close pitches mix. The throbs come at a rate equal to the difference between the two frequencies. Musicians listen for them when they tune.
cochleaThe inner ear's coiled, fluid-filled chamber. Cochlea is Latin for snail shell. Vibrations reach it from the eardrum by way of three tiny bones.
ear canalThe short passage that funnels sound to the eardrum. In an adult it is about 25 millimeters (1 inch) long.
fundamentalThe lowest tone in a note, which gives it its pitch. It is usually the tone heard most strongly. Fundamental frequency is its full name.
hearing rangeThe span of frequencies an animal can hear. For people it is usually given as 20 to 20,000 hertz. Elephants hear down to 16 hertz, and some bats and dolphins above 100,000.
larynxThe hollow organ in the neck where the voice starts. Voice box is its everyday name. It houses the vocal cords, which vibrate as air from the lungs passes between them.
megaphoneA horn held to the mouth to aim and boost a voice. It is shaped like a cone. The speaker talks into the narrow end, and the sound waves spread out of the wide end.
outer earThe visible ear and its canal, which gather sound. The visible flap is called the auricle or pinna. Many mammals can turn it toward a sound; most people cannot.
overtoneA higher, fainter tone sounding above a note's pitch. The mix of overtones is why a guitar and a piano sound different on the same note. That quality is called timbre.
sound intensityThe sound power passing through each square meter. Its unit is the watt per square meter.
soundproofingTreating a room to stop sound getting in or out. Distance, barriers that reflect sound and materials that absorb it are all used.
How this list was compiled: Term list chosen for this site on 2026-10-12. Each meaning is written in our own words and was checked that day against the article on the term in the English Wikipedia (https://en.wikipedia.org/), whose text is under the Creative Commons Attribution-ShareAlike license: Vibration, Transmission medium, Pitch (music), Frequency, Amplitude, Wavelength, Loudness, Echo, Decibel, Hertz, Speed of sound, Longitudinal wave, Mechanical wave, Rarefaction, Reverberation, Doppler effect, Resonance, Ultrasound, Infrasound, Animal echolocation, Mach number, Thunder, Anechoic chamber, Sound barrier, Sonic boom, Ear canal, Cochlea, Cochlear nerve, Larynx, Vocal cords, Outer ear, Hearing range, Overtone, Fundamental frequency, Timbre, Beat (acoustics), Sound intensity, Soundproofing and Megaphone. Sound wave, compression, medium and larynx were also read in Wiktionary, the free dictionary (https://en.wiktionary.org/). What a sound wave is, compressions and rarefactions as high and low pressure, amplitude and loudness, and the two A notes of 110 and 220 hertz were checked against Introduction to sound waves of BBC Bitesize (https://www.bbc.co.uk/bitesize/articles/zpm3r2p). Frequency and pitch, the range of human hearing, ultrasound, infrasound, the hearing of dogs, bats and elephants, and the 120 decibels of thunder were checked against Understanding Sound of the U.S. National Park Service (https://www.nps.gov/subjects/sound/understandingsound.htm). The path from the ear canal to the auditory nerve is from How Do We Hear? of the National Institute on Deafness and Other Communication Disorders (https://www.nidcd.nih.gov/health/how-do-we-hear). The fact after each meaning is from the same pages. Licence: own work
How it works
This sound waves vocabulary worksheet prints vibration, medium, pitch, frequency, amplitude, wavelength, echo, decibel and hertz, among twelve terms, with their meanings mixed up on the right. The answer key is the last page.
Read the full guide
How sound travels
Set opens on Sound wave basics. The second set has longitudinal wave, compression, rarefaction, reverberation, Doppler effect, resonance, ultrasound, infrasound, echolocation, Mach number, thunder and anechoic chamber.
Hearing and making sound
The third set has outer ear, ear canal, cochlea, auditory nerve, larynx, hearing range, overtone, fundamental, beat, sound intensity, soundproofing and megaphone.
Crest and trough are not terms here: a sound wave has compressions and rarefactions. Both words are on the waves word search.
Questions and answers
What is the difference between frequency and pitch?
Frequency is a physical count: vibrations per second, in hertz. Pitch is how low or high a sound seems to a listener. Raise the frequency and the pitch goes up, which is why the two words are often used as one.
Does sound travel faster in water or in air?
In water. Sound moves at about 343 meters a second in air, about 1,481 in fresh water and about 5,120 in iron. As a rule it is slowest in gases, faster in liquids and fastest in solids.
What happens when a plane breaks the sound barrier?
It makes a sonic boom. Shock waves form when anything moves through the air faster than sound, and a listener hears them as a bang like a thunderclap. The crack of a whip is a small sonic boom.
How do we hear sound?
Sound waves travel down the ear canal and make the eardrum vibrate. Three tiny bones pass the vibrations to the fluid-filled cochlea, where hair cells turn them into electrical signals. The auditory nerve carries the signals to the brain.