Sound Waves: Characteristics and Applications

Comprehensive vocabulary flashcards covering the key terms, physical principles, characteristics, formulas, and applications of sound waves from Chapter 10.

Sonority

A property of some metals where sound is produced when struck with an object.

Vibration

The periodic to-and-fro motion (oscillations) of an object.

Source of Sound

The vibrating object that produces sound.

Vocal Cords

Tightly stretched muscular flaps located inside the voice box (larynx) in the throat that vibrate to produce sound.

Tuning Fork

A U-shaped metal bar with a stem, usually made of steel or aluminium, whose prongs (or tines) vibrate when struck against a rubber pad.

Medium

The material (solid, liquid, or gas) through which sound travels or propagates.

Vacuum

A space where there is no matter or medium, through which sound cannot propagate.

Compression ($C$)

A region in a longitudinal wave where particles are pushed close together, resulting in a higher density than the average density.

Rarefaction ($R$)

A region in a longitudinal wave where particles are spread farther apart, resulting in a lower density than the average density.

Sound Wave

A disturbance consisting of a series of alternating compressions and rarefactions propagating through a medium without the actual flow of the medium's particles.

Longitudinal Wave

A wave in which the particles of the medium vibrate back and forth parallel to the direction of wave propagation.

Mechanical Wave

A wave that requires a material medium for its propagation.

Transverse Wave

A wave in which the particles vibrate in a direction perpendicular to the direction of wave propagation.

Crest

The highest point on the graphical representation of a sound wave, representing maximum density in a compression.

Trough

The lowest point on the graphical representation of a sound wave, representing minimum density in a rarefaction.

Wavelength ($\lambda$)

The distance between two consecutive crests or two consecutive troughs of a wave, measured in metres ($\text{m}$).

Frequency ($\nu$)

The number of complete density oscillations at a fixed point per unit time, measured in hertz ($\text{Hz}$) or per second ($\text{s}^{-1}$).

Time Period ($T$)

The time taken for one complete density oscillation at a fixed point, measured in seconds ($\text{s}$), related to frequency by $\nu = \frac{1}{T}$.

Amplitude

The maximum change in the density of the medium in a compression or rarefaction compared to the average density.

Intensity of Sound

The amount of sound energy passing through a unit area perpendicular to the direction of wave propagation in a unit time.

Speed of Sound ($v$)

The distance that a point on a wave travels in unit time, calculated as $\text{speed} = \text{wavelength} \times \text{frequency}$ ($v = \lambda \times \nu$).

Pitch

The human perception of sound frequency, where higher frequencies are perceived as shrill and lower frequencies as deep.

Audible Range

The range of sound frequencies detectable by normal human hearing, spanning from $20\,\text{Hz}$ to $20{,}000\,\text{Hz}$ ($20\,\text{kHz}$).

Infrasonic Waves (Infrasound)

Sound waves with frequencies below $20\,\text{Hz}$, undetectable by human ears but detectable by animals like elephants.

Ultrasonic Waves (Ultrasound)

Sound waves with frequencies above $20\,\text{kHz}$ ($20{,}000\,\text{Hz}$), undetectable by human ears but detectable by animals like bats and dolphins.

Loudness

The subjective human perception of the amplitude of a sound wave, commonly measured in decibels ($\text{dB}$).

Tone

A sound consisting of a single frequency, such as that produced by an oral whistle or a vibrating tuning fork.

Timbre

The distinct quality of a sound that allows listeners to distinguish between different instruments playing the same note at the same loudness.

Octave

The interval between two musical notes where one note has double the fundamental frequency of the other.

Syaahi

A black patch applied at the centre of the drumhead membrane on Indian percussion instruments (such as the tabla or mridangam) that alters vibration and tonal control.

Echo

A reflected sound that arrives at the listener's ear at least $0.1\,\text{s}$ after the original sound, allowing it to be perceived as a distinct repetition.

Reverberation

The persistence of sound in an enclosed space caused by multiple reflections arriving with time intervals of less than $0.05\,\text{s}$.

Echolocation

The sensory ability of animals (such as bats, dolphins, and whales) to locate obstacles and prey by emitting ultrasonic bursts and sensing the reflected echoes.

SONAR

An acronym for Sound Navigation and Ranging; a technique using reflected ultrasonic waves in water to determine the distance, direction, and speed of underwater objects.