Soundwave

A sound wave is a mechanical disturbance that propagates through a medium by alternating regions of compression and rarefaction, transferring energy from one location to another. In gases and liquids, sound is primarily a longitudinal wave, with particles oscillating in the direction of travel; in solids it can propagate as longitudinal waves with accompanying transverse motion depending on the material.

Key properties of a sound wave include frequency, which determines pitch; amplitude, which relates to loudness; wavelength, and propagation speed. The speed of sound depends on the medium and its conditions, such as temperature and pressure. For example, in air at room temperature the speed is about 343 meters per second, in water around 1,480 m/s, and in typical solids it is several thousand meters per second. Higher temperatures generally increase the speed in gases.

As a wave, sound involves the transfer of energy without a net movement of the medium. When encountering boundaries between media, part of the wave is reflected, part is transmitted, and part is absorbed, with the proportions determined by the impedance difference. Waves lose energy as they travel, especially at higher frequencies, leading to attenuation.

Perception and measurement: the human audible range is roughly 20 Hz to 20 kHz. Sound level is expressed in decibels, a logarithmic scale related to the intensity of the pressure variation. Microphones and receivers convert pressure fluctuations into electrical signals for recording, analysis, and transmission.

Applications include communication and speech, music, sonar and underwater navigation, ultrasound imaging in medicine, and nondestructive testing in industry. Sound waves are also studied in acoustics to understand how environments, materials, and geometries affect propagation and perception.