'''Acoustics''' is the branch of [[physics]] concerned with the study of [[sound]], [[ultrasound]] and [[infrasound]] (all mechanical [[wave]]s in [[gas]]es, [[liquid]]s, and [[solid]]s). A [[scientist]] who works in the field of acoustics is an '''acoustician'''. The application of acoustics in [[technology]] is called [[acoustical engineering]]. There is often much overlap and interaction between the interests of acousticians and acoustical engineers.

The origins of acoustic research began with the study of mechanical vibrations and the radiation of these vibrations through mechanical waves, and still continues today. Research was done to look into the many aspects of the fundamental physical processes involved in waves and sound and into possible applications of these processes in modern life. The study of sound waves also led to physical principles that can be applied to the study of all waves.

The study of acoustics has been fundamental to many developments in the arts. Some of these, especially in the area of musical scales and instruments, were only explained theoretically by scientists after long years of long experimentation by artists. For example, much of what is now known about architectural acoustics was actually learned by trial and error over centuries of experience and was only recently formalized into a science.

Other applications of acoustic technology are in the study of geologic, atmospheric, and underwater phenomena. [[Psychoacoustics]], the study of the physical effects of sound on biological systems, has been of interest since Pythagoras first heard the sounds of vibrating strings and of hammers hitting anvils in the 6th century BC, but the application of modern ultrasonic technology has only recently provided some of the most exciting developments in medicine. The [[ear]] itself is another biological instrument dedicated to receiving certain wave vibrations and interpreting them as sound. Recent studies by Daniel Statnekov and others, study sound and its effect on the human brain.

The word "acoustic" is derived from the ancient Greek word ακουστός, meaning able to be heard (Woodhouse, 1910, 392). The Latin synonym is "sonic". After acousticians had extended their studies to frequencies above and below the audible range, it became conventional to identify these frequency ranges as "ultrasonic" and
"infrasonic" respectively, while letting the word "acoustic" refer to the entire frequency range without limit.

== Divisions of acoustics ==

{{Cleanup-list|December 2006}}

The following are the main sub-disciplines of acoustics:<ref>{{cite web | title=PACS | work=American Institute of Physics, Physics and Astronomy Classification Scheme | url=http://www.aip.org/pacs/pacs03/appendix.html}}</ref>
*'''[[Acoustical measurements and instrumentation]]'''
*'''[[Audio signal processing|Acoustic signal processing]]'''
*'''[[Aeroacoustics]]''': study of aerodynamic sound, generated when a fluid flow interacts with a solid surface or with another flow. It has particular application to [[aeronautics]], examples being the study of sound made by flying jets and the physics of [[shock wave]]s ([[sonic boom]]s).
*'''[[Architectural acoustics]]''': study of sound waves distribution in variously shaped enclosed or partly enclosed spaces with effects of sound waves on objects of different shapes which are in their way. Mostly concentrated on how sound and buildings interact, including the behavior of sound in [[concert hall]]s and auditoriums but also in office buildings, factories and homes.
*'''[[Bioacoustics]]''': study of the use of sound by animals such as whales, dolphins, bats etc.
*'''[[Biomedical acoustics]]''': study of the use of sound in medicine, for example the use of [[ultrasound]] for diagnostic and therapeutic purposes.
*'''[[Environmental noise]]''': study of the sound propagation in the human environment, [[noise health effects]] and noise mitigation analysis.
*'''[[Musical acoustics]]''': study of the physics of [[musical instruments]].
*'''[[Nonlinear Acoustics]]''': study of high amplitude waves and related phenomena, such as [[parametric array]]s and [[sonic boom]]s.
*'''[[Psychoacoustics]]''': study of subjective reaction of living beings to sound, [[hearing (sense)|hearing]], [[perception]], and [[sound localization|localization]].
*'''[[Physiological acoustics]]''': study of the mechanical, electrical and biochemical function of [[hearing (sense)|hearing]] in living organisms.
*'''[[Physical acoustics]]''': study of the propagation of acoustic waves and of the detailed interaction of sound with materials and fluids including, for example, [[sonoluminescence]] (the emission of light by bubbles in a liquid excited by sound) and [[thermoacoustics]] (the interaction of sound and heat).
*'''[[Speech communication]]''': study of how speech is produced, the analysis of speech signals and the properties of speech transmission, storage, recognition and enhancement.
*'''[[Structural acoustics and vibration]]''': study of how sound and mechanical structures interact; for example, the transmission of sound through walls and the [[radiation of sound]] from [[vehicle]] panels.
*'''[[Transduction]]''': study of how sound is generated and measured by [[loudspeaker]]s, [[microphone]]s, [[sonar|sonar projector]]s, [[hydrophone]]s, [[ultrasonic transducer]]s and [[sensor]]s.
*'''[[Ultrasonics]]''': study of high [[frequency]] sound, beyond the range of human hearing.
*'''[[Underwater acoustics]]''': study of the propagation of sound in water.

== See also ==
{{wikisourcepar|The New Student's Reference Work/Acoustics|Acoustics}}
* [[Acoustic emission testing]] listens to the sounds from a solid material or from deep within the earth. Such sounds can be caused by cracking, fiber breakage, [[stick-slip phenomenon]], cavitation, and impact.
* [[Archaeoacoustics]]

== References ==
<references/>
* Leo L. Beranek. ''Acoustics''. First edition - 1954. Revised edition - 1986. American Institute of Physics, New York: 1954 (1986). ISBN 088318494X
* Malcolm J. Crocker. ''Encyclopedia of Acoustics''. Wiley, New York, 1997.
* Frederick V. Hunt. ''Origins in Acoustics: The Science of Sound from Antiquity to the Age of Newton. Yale University Press'', New Haven, CT, 1978. ISBN 0300022204
* Raymond D. Kent. ''Acoustic Analysis of Speech, 2nd Edition''. Singular, 2001. ISBN 0769301126
* Christopher L. Morfey. ''Dictionary of Acoustics''. Academic Press, San Diego, 2001. ISBN 0-12-506940-5
* Philip M. Morse and K. U. Ingard. ''Theoretical Acoustics''. McGraw-Hill Education, 1968. ISBN 0070433305
* J. M. Pickett. ''The Acoustics of Speech Communication: Fundamentals, Speech Perception Theory, and Technology''. Allyn & Bacon, 1998. ISBN 0205198872
* Allan D. Pierce. ''Acoustics: An Introduction to its Physical Principles and Applications''. American Institute of Physics, New York, 1989.
* Kenneth N. Stevens. ''Acoustic Phonetics''. The MIT Press, Cambridge, MA, 1999. ISBN 026219404X
* S.C. Woodhouse. ''English-Greek Dictionary''. 1910.

== External links ==

[[Category:Acoustics]]
[[Category:Physics]]
[[Category:Sound]]

[[az:Akustika]]
[[bg:Акустика]]
[[ca:Acústica]]
[[cs:Akustika]]
[[da:Akustik]]
[[de:Akustik]]
[[et:Akustika]]
[[el:Ακουστική]]
[[es:Acústica]]
[[eo:Akustiko]]
[[fr:Acoustique]]
[[gl:Acústica]]
[[ko:음향학]]
[[hr:Akustika]]
[[io:Akustiko]]
[[it:Acustica]]
[[he:אקוסטיקה]]
[[lb:Akustik]]
[[ms:Akustik]]
[[nl:Akoestiek]]
[[ja:音響学]]
[[no:Akustikk]]
[[nn:Akustikk]]
[[pl:Akustyka]]
[[pt:Acústica]]
[[ro:Acustică]]
[[ru:Акустика]]
[[simple:Acoustics]]
[[sk:Akustika]]
[[sl:Akustika]]
[[sr:Акустика]]
[[sh:Akustika]]
[[fi:Akustiikka]]
[[sv:Akustik]]
[[ta:ஒலியியல்]]
[[th:สวนศาสตร์]]
[[vi:Âm học]]
[[tr:Akustik]]
[[uk:Акустика]]
[[zh:声学]]