Sound wave
A sound wave is a mechanical disturbance that travels through a material medium as variations in pressure, particle displacement, or both.
Longitudinal wave: A wave in which particles oscillate parallel to the direction of propagation. In fluids, sound travels through alternating compressions and rarefactions along its direction of travel.
Mechanical wave: A disturbance that propagates through matter by the motion and interaction of its particles. Sound belongs to this family because it requires matter to carry its disturbance.
Acoustics: The science of sound, including its production, transmission, and effects. Acoustics studies sound waves across rooms, instruments, materials, and other settings.
Electromagnetic wave: A propagating oscillation of electric and magnetic fields that can travel through vacuum. Unlike sound, electromagnetic waves do not require a material medium.
Compression wave: A wave characterized by regions of increased and decreased pressure or density. These pressure variations carry sound through air and other fluids.
Pressure: Force exerted per unit area by a fluid or material. Sound in a fluid is associated with small, propagating changes from ambient pressure.
Ultrasound: Sound at frequencies above the upper limit of typical human hearing. Ultrasound uses high-frequency sound waves for imaging, sensing, and material inspection.
Transverse wave: A wave in which the oscillation is perpendicular to the direction of propagation. Ordinary sound in fluids is longitudinal, though solids can also support shear sound waves.
Acoustic impedance: A measure of how strongly a medium resists acoustic motion, determined by its density and sound speed. Impedance helps determine how sound energy transfers between neighboring materials.
Displacement: A change in position relative to a reference point. Particle displacement describes how the medium’s material moves as sound passes.