Properties and Detection of Sound

Front

Sound Wave Noun

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[sound wayv]

Back

Sound Wave

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A pressure oscillation transmitted through matter, which is created by a vibrating source that causes particles to collide.

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Example: This diagram shows a sound wave travels as a longitudinal wave with areas of compression and rarefaction, which can be graphed to show properties like wavelength and amplitude.

Front

Longitudinal Wave Noun

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[lon-ji-tood-n-ul wayv]

Back

Longitudinal Wave

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A wave in which the motion of the medium's particles is parallel to the direction of the wave's motion.

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Example: This diagram shows a longitudinal wave, where a particle (red dot) moves back and forth, parallel to the direction the wave travels.

Front

Frequency Noun

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[free-kwen-see]

Back

Frequency

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The number of pressure oscillations that occur each second, which is the primary determinant of a sound's pitch.

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Example: This diagram shows that a high-pitch sound (whistle) has a higher frequency (more waves) in a set time than a low-pitch sound (bass guitar).

Front

Wavelength Noun

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[wayv-length]

Back

Wavelength

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The distance between successive regions of either high pressure or low pressure in a sound wave.

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Example: This diagram shows a wave and labels the wavelength as the distance from the top of one wave (crest) to the top of the next one.

Front

Echo Noun

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[ek-oh]

Back

Echo

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A reflected sound wave that is perceived by an observer sometime after the original sound is produced.

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Example: This diagram shows a sound wave traveling from a source (voice), bouncing off a surface (wall), and returning to the listener as a reflected wave, or echo.

Front

Sonar Noun

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[soh-nar]

Back

Sonar

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A system that utilizes reflected sound waves, or echoes, to determine the distance to a reflective object.

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Example: A device sends out a sound wave, which travels until it hits an object. The wave then reflects, or echoes, back to the device.

Front

Tympanic Membrane Noun

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[tim-pan-ik mem-brayn]

Back

Tympanic Membrane

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A thin disk in the ear, also known as the eardrum, that vibrates when sound waves enter the auditory canal.

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Example: This diagram shows the tympanic membrane, or eardrum, at the end of the ear canal, which vibrates when sound waves strike it.

Front

Cochlea Noun

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[kok-lee-uh]

Back

Cochlea

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A spiral-shaped, fluid-filled structure in the inner ear that converts mechanical vibrations into electrical nerve impulses.

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Example: This diagram shows the snail-shaped cochlea inside the inner ear, which is where sound vibrations are converted into nerve signals for the brain to interpret.

Front

Pitch Noun

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[pich]

Back

Pitch

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The perceived highness or lowness of a sound, which is determined by the frequency of the sound wave.

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Example: This diagram compares two sound waves over the same time period, showing that a low-pitch sound has fewer waves (lower frequency) than a high-pitch sound.

Front

Amplitude Noun

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[am-pli-tood]

Back

Amplitude

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The measure of the variation in pressure within a wave, which is the primary factor in a sound's intensity.

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Example: This diagram shows a wave and uses a double-headed arrow to indicate amplitude, the maximum distance from the wave's resting position to its crest.