Sound Wave
This definition page has been automatically generated. You can help ExoDictionary by expanding, updating, or correcting it. |
| This autostub has not yet had its initial copyediting proof and may contain significant formatting and even factual errors. You can improve Exodictionary by cleaning up the page markup and verifying that the definition is correct and then removing this tag. |
| This autostub has not yet had its initial categorization proof and may be categorized incorrectly. You can improve Exodictionary by removing inappropriate categories and then removing this tag. |
Sound Wave
</dt>
A mechanical disturbance advancing with infinite velocity through an
elastic medium and consisting of longitudinal displacements of the medium,
i.e., consisting of compressional and rarefactional displacements parallel to
the direction of advance of the disturbance; a longitudinal wave. Sound waves
are small-amplitude adiabatic
oscillations. The wave equation governing the motion of sound waves has the
form
where Missing Image:img src="SP7_s_files/del.gif"2 is the Laplace operator,
Missing Image:img src="SP7_s_files/phisms.gif" is the velocity potential, c is the speed
of sound, and t is the time; the density variations and velocities are
small. As so defined, this includes waves outside the frequency limits of
human hearing, which limits customarily define sound. Also called acoustic
wave, sonic wave. See ultrasonic,
infrasonic,
pressure
wave.
</dd>
Gases, liquids, and solids transmit sound waves, and the propagation
velocity is characteristic of the nature and physical state of each of these
media. In those cases where a steadily vibrating sound generator acts as a
source of waves, one may speak of a uniform wave train; but in other cases
(explosions, lightning discharges) a violent initial disturbance sends out a
principal wave, followed by waves of more or less rapidly diminishing
amplitude. [[/a>|/a>
]]
References
This article is based on NASA's Dictionary of Technical Terms for Aerospace Use
