A drum produces sound via a vibrating membrane.

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.^[1]

Propagation of sound[link]

Sound is a sequence of waves of pressure that propagates through compressible media such as air or water. (Sound can propagate through solids as well, but there are additional modes of propagation). During propagation, waves can be reflected, refracted, or attenuated by the medium.^[2]

The behavior of sound propagation is generally affected by three things:

• A relationship between density and pressure. This relationship, affected by temperature, determines the speed of sound within the medium.
• The propagation is also affected by the motion of the medium itself. For example, sound moving through wind. Independent of the motion of sound through the medium, if the medium is moving, the sound is further transported.
• The viscosity of the medium also affects the motion of sound waves. It determines the rate at which sound is attenuated. For many media, such as air or water, attenuation due to viscosity is negligible.

When sound is moving through a medium that does not have constant physical properties, it may be refracted (either dispersed or focused).^[2]

Perception of sound[link]

Human ear

The perception of sound in any organism is limited to a certain range of frequencies. For humans, hearing is normally limited to frequencies between about 20 Hz and 20,000 Hz (20 kHz)^[3], although these limits are not definite. The upper limit generally decreases with age. Other species have a different range of hearing. For example, dogs can perceive vibrations higher than 20 kHz, but are deaf to anything below 40 Hz. As a signal perceived by one of the major senses, sound is used by many species for detecting danger, navigation, predation, and communication. Earth's atmosphere, water, and virtually any physical phenomenon, such as fire, rain, wind, surf, or earthquake, produces (and is characterized by) its unique sounds. Many species, such as frogs, birds, marine and terrestrial mammals, have also developed special organs to produce sound. In some species, these produce song and speech. Furthermore, humans have developed culture and technology (such as music, telephone and radio) that allows them to generate, record, transmit, and broadcast sound. The scientific study of human sound perception is known as psychoacoustics.

Physics of sound[link]

Spherical compression waves

The mechanical vibrations that can be interpreted as sound are able to travel through all forms of matter: gases, liquids, solids, and plasmas. The matter that supports the sound is called the medium. Sound cannot travel through a vacuum.

Longitudinal and transverse waves[link]

Sound is transmitted through gases, plasma, and liquids as longitudinal waves, also called compression waves. Through solids, however, it can be transmitted as both longitudinal waves and transverse waves. Longitudinal sound waves are waves of alternating pressure deviations from the equilibrium pressure, causing local regions of compression and rarefaction, while transverse waves (in solids) are waves of alternating shear stress at right angle to the direction of propagation.

Matter in the medium is periodically displaced by a sound wave, and thus oscillates. The energy carried by the sound wave converts back and forth between the potential energy of the extra compression (in case of longitudinal waves) or lateral displacement strain (in case of transverse waves) of the matter and the kinetic energy of the oscillations of the medium.

Sound wave properties and characteristics[link]

Sinusoidal waves of various frequencies; the bottom waves have higher frequencies than those above. The horizontal axis represents time.

Sound waves are often simplified to a description in terms of sinusoidal plane waves, which are characterized by these generic properties:

• Frequency, or its inverse, the period
• Wavelength
• Wavenumber
• Amplitude
• Sound pressure
• Sound intensity
• Speed of sound
• Direction

Sometimes speed and direction are combined as a velocity vector; wavenumber and direction are combined as a wave vector.

Transverse waves, also known as shear waves, have the additional property, polarization, and are not a characteristic of sound waves.

Speed of sound[link]

U.S. Navy F/A-18 breaking the sound barrier. The white halo is formed by condensed water droplets thought to result from a drop in air pressure around the aircraft (see Prandtl-Glauert Singularity).^[4][5]

The speed of sound depends on the medium the waves pass through, and is a fundamental property of the material. In general, the speed of sound is proportional to the square root of the ratio of the elastic modulus (stiffness) of the medium to its density. Those physical properties and the speed of sound change with ambient conditions. For example, the speed of sound in gases depends on temperature. In 20 °C (68 °F) air at the sea level, the speed of sound is approximately 343 m/s (1,230 km/h; 767 mph) using the formula "v = (331 + 0.6 T) m/s". In fresh water, also at 20 °C, the speed of sound is approximately 1,482 m/s (5,335 km/h; 3,315 mph). In steel, the speed of sound is about 5,960 m/s (21,460 km/h; 13,330 mph).^[6] The speed of sound is also slightly sensitive (a second-order anharmonic effect) to the sound amplitude, which means that there are nonlinear propagation effects, such as the production of harmonics and mixed tones not present in the original sound (see parametric array).

Acoustics[link]

Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical or audio engineer. The application of acoustics can be seen in almost all aspects of modern society with the most obvious being the audio and noise control industries.

Noise[link]

Noise is a term often used to refer to an unwanted sound. In science and engineering, noise is an undesirable component that obscures a wanted signal.

Sound pressure level[link]

Sound pressure is the difference, in a given medium, between average local pressure and the pressure in the sound wave. A square of this difference (i.e., a square of the deviation from the equilibrium pressure) is usually averaged over time and/or space, and a square root of this average provides a root mean square (RMS) value. For example, 1 Pa RMS sound pressure (94 dBSPL) in atmospheric air implies that the actual pressure in the sound wave oscillates between (1 atm Failed to parse (Missing texvc executable; please see math/README to configure.): -\sqrt{2}

Pa) and (1 atm Failed to parse (Missing texvc executable; please see math/README to configure.): +\sqrt{2}
Pa), that is between 101323.6 and 101326.4 Pa. Such a tiny (relative to atmospheric) variation in air pressure at an audio frequency is perceived as a deafening sound, and can cause hearing damage, according to the table below.

As the human ear can detect sounds with a wide range of amplitudes, sound pressure is often measured as a level on a logarithmic decibel scale. The sound pressure level (SPL) or L_p is defined as

Failed to parse (Missing texvc executable; please see math/README to configure.): L_\mathrm{p}=10\, \log_{10}\left(\frac{{p}^2}{{p_\mathrm{ref}}^2}\right) =20\, \log_{10}\left(\frac{p}{p_\mathrm{ref}}\right)\mbox{ dB}\,

where p is the root-mean-square sound pressure and Failed to parse (Missing texvc executable; please see math/README to configure.): p_\mathrm{ref}

is a reference sound pressure. Commonly used reference sound pressures, defined in the standard ANSI S1.1-1994, are 20 µPa in air and 1 µPa in water. Without a specified reference sound pressure, a value expressed in decibels cannot represent a sound pressure level.

Since the human ear does not have a flat spectral response, sound pressures are often frequency weighted so that the measured level matches perceived levels more closely. The International Electrotechnical Commission (IEC) has defined several weighting schemes. A-weighting attempts to match the response of the human ear to noise and A-weighted sound pressure levels are labeled dBA. C-weighting is used to measure peak levels.

Equipment for dealing with sound[link]

Equipment for generating or using sound includes musical instruments, hearing aids, sonar systems and sound reproduction and broadcasting equipment. Many of these use electro-acoustic transducers such as microphones and loudspeakers.

Sound measurement[link]

• Decibel, Sone, mel, Phon, Hertz
• Sound pressure level, Sound pressure
• Particle velocity, Acoustic velocity
• Particle displacement, Particle amplitude, Particle acceleration
• Sound power, Acoustic power, Sound power level
• Sound energy flux
• Sound intensity, Acoustic intensity, Sound intensity level
• Acoustic impedance, Sound impedance, Characteristic impedance
• Speed of sound, Amplitude

See also[link]

References[link]

External links[link]

Wikiquote has a collection of quotations related to: Sound

Wikibooks has more on the topic of Sound

Wikimedia Commons has media related to: Sound

Wikisource has original text related to this article: Sound

• Sounds Amazing; a KS3/4 learning resource for sound and waves
• HyperPhysics: Sound and Hearing
• Introduction to the Physics of Sound
• Hearing curves and on-line hearing test
• Audio for the 21st Century
• Conversion of sound units and levels
• Sound calculations
• Audio Check: a free collection of audio tests and test tones playable on-line
• More Sounds Amazing; a sixth-form learning resource about sound waves

An entity is something that exists by itself, although it need not be of material existence. In particular, abstractions and legal fictions are usually regarded as entities. In general, there is also no presumption that an entity is animate.

In business, an entity is a person, department, team, corporation, cooperative, partnership, or other group with whom it is possible to conduct business.

Sometimes, the word entity is used in a general sense of a being, whether or not the referent has material existence, e.g., is often referred to as an entity with no corporeal form (non-physical entity), such as a language. It is also often used to refer to ghosts and other spirits.

The word entitative is the adjective form of the noun entity. Something that is entitative is "considered as pure entity; abstracted from all circumstances", that is, regarded as entity alone, apart from attendant circumstances.

See also[link]

• Digital identity
• Entity class
• Entity realism, a form of scientific realism
• Entitativity
• Object (philosophy)
• Ontology, the study of being, existence and entities

Look up record in Wiktionary, the free dictionary.

A recording, Record, Records or The Record may mean:

An item or collection of data:

• Gramophone record (also called "phonograph record"), mechanical analog audio storage medium
• Sound recording and reproduction
• Record (computer science), a data structure
  • Storage record, a basic input/output structure
  • Record (database), a set of fields in a database related to one entity
  • Boot record, record used to start an operating system
• Document for administrative use
  • Business record of economic transactions
  • Medical record of a person's medical history and treatments
  • Service record, usually associated with military service
  • Minutes, a summary of the proceedings at a meeting
  • Public records, information that has been filed or recorded by public agencies
  • Docket (court), the summary of proceedings in a court (US)
  • A transcript is a verbatim record of some proceedings, in particular a court transcript is a record of a law court case or similar procedure
  • Recording (real estate), the act of documenting real estate transactions
  • Criminal record, a list of a person's criminal convictions.
  • Anything which is recorded in writing or otherwise for future reference
• World record, an unsurpassed accomplishment or statistic
• Win–loss record (pitching), the number of wins and losses a baseball pitcher has accumulated
• Archaeological record, the body of archaeological evidence

Entertainment:

• The Records, an English power pop band
• Records (album), a 1982 album by rock band Foreigner
• The Record (album), a 1982 punk rock album by the band Fear
• The Record (film), a South Korean film directed by Ki-Hun Kim

Software:

• Record (software), a music recording program

Periodicals:

• In the United States:
  • The Yale Record, the country's oldest college humor magazine, operated out of New Haven, Connecticut
  • The Record (Bergen County), a newspaper in Bergen County, New Jersey
  • The Record (Stockton), a newspaper in Stockton, California
  • The Record (Troy), a newspaper in Troy, New York
  • The Philadelphia Record, a newspaper in Philadelphia published 1877–1947
• In Canada:
  • The Record (Waterloo Region), a newspaper in Waterloo Region, Ontario
  • The Record (Sherbrooke), a newspaper in Quebec
  • The Record (magazine), a former trade magazine of the Canadian music industry
• Elsewhere:
  • Record (newspaper), a Portuguese sports newspaper
  • The Record Music Magazine, an Indian publication featuring music personalities
  • Récord, a Mexican sports newspaper
  • Record (magazine), the official church paper of the South Pacific Division of Seventh-day Adventists

Broadcasting:

• Rede Record, a Brazilian TV network
• Record News, the Rede Record's news channel 1

People:

• Max Records, American child actor

Brand names:

• Record (agricultural vehicles), a Greek vehicle manufacturer

This disambiguation page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly to the intended article.

'Jack Smooth, real name Ron Wells, born in London 1970.

Ron is often credited as the pioneer of Jungle techno. During his career Ron has produced over 200 dance music records, spanning many genres.

Ron began his musical life as a Pirate Radio DJ in 1987 on the Crystal, Medina & WLR stations in London.

During 1987 Ron met Chris Simmonds at Medina Radio and they went on to form Wax Factory Productions in 1989. Wax Factory were one of the first UK dance music labels to deal directly with record shops - not having a distribution deal. In years to come, Wax factory would earn cult status as an underground UK house and techno label. Many, to this day, believe that their productions were from the USA, due to their authentic Techno sound.

Around 1991 Ron formed Sound Entity Records as a solo project where he was introduced to Phil Wells of Basement Records by DJ Loftgroover. Ron and Phil quickly developed a powerful relationship where Ron went on to produce and co-write the majority of the first 30 releases on the label. The Basement Records label today is often credited as the most influential label that the Jungle Techno scene produced.

In 1992 Ron masterminded the hit single Trip to Trumpton project with Urban Hype, where he co-wrote and produced the single. The single reached no 6 in the National Charts and kept its top ten status for one month.

1993 saw Ron forming Fast Floor Productions (sub label of Basement Records) with Paul Clarke, where they produced many Jungle Techno anthems. Their music was highly regarded for its combination on musicality and dance floor presence by many DJs, in particular, Top Buzz. In 1994 Fast Floor produced an LP called "On a Quest For Intelligence" which has gone on to demand crown jewels prices on the second-hand music market.

In 1995 Ron Wells and Paul Clarke formed Earl Grey. This was specifically a drum and bass / jazz crossover project. They signed to MCA music publishing and Carl Cox's Worldwide Ultimatum label to release the LP "Purveyors of the New Groove".

During 1996 Ron and Paul could sense that a decline in the music industry was on the horizon. This lead them to take the decision to leave music behind for a while and concentrate on starting a commercial business. They changed their name to Fast Floor Multimedia Ltd in 1997 and embarked on building a marketing communications company, which still exists today.

Moving into business however has not meant the end of Ron and Paul's music careers. They both have a considerable number of works within the Sonoton Music Library in Germany and they continue to write music to this day.

External links[link]

• Jack Smooth discography at Discogs
• Jack Smooth at Fantazia
• Jack Smooth at Roll Da Beats

Alex Reece (born Alexander Charles Ernest Reece,^[1] Barnet, England) was an influence of the jazzstep sound, a mix of drum and bass and jazz, and one of the musicians under the Metalheadz collective, who also works under the pseudonym of Fallen Angels.

Career[link]

Although he was most interested in acid house and early Detroit techno, Reece came to prominence in the mid 1990s as a jungle star.^[2] Reece began DJing in the late 1980s.^[2] In 1992 Jack Smooth offered Reece a trainee studio engineer job, and Reece went on to engineer for Smooth on many of the early Basement Records releases.^[2] Reece first tried house (recording with his brother, Oscar, under the name of Exodus), but graduated to drum and bass.^[2]

His initial releases appeared on the Sinister, Creative Wax, and Moving Shadow record labels, but Reece made his name with Goldie's Metalheadz Records. Single releases "Basic Principles" and "Pulp Fiction" became jungle standards. The latter is originally called "Pulp Friction" as on Alex Reece's debut album So Far. Supposedly there are two different songs out - "Pulp Friction" and "Pulp Fiction". But even when the album version is used in a set it is incorrectly referred to as "Pulp Fiction".^[2]

Reece cemented his reputation with additional recordings as Jazz Juice (for Precious Materials), Lunar Funk (for Mo'Wax), and the Original Playboy (for R&S).^[2] In early 1996, Reece secured a recording contract with Island Records recruited him for their Quango subsidiary.^[2] His debut album, So Far was released in September 1996, but whilst the issue was well received in most circles, the jungle underground - led by Goldie - had practically disowned Reece by that time.^[2] His 1996 singles "Feel the Sunshine", "Candles" and "Acid Lab" were released under the Fourth & Broadway banner without real commercial success.^[3]

References[link]

External links[link]

• Alex Reece discography at Discogs
• Alex Reece at rolldabeats