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Headroom (audio)
In digital and analog audio, headroom refers to the amount by which the signal-handling capabilities of an audio system can exceed a designated nominal level. Headroom can be thought of as a safety zone allowing transient audio peaks to exceed the nominal level without damaging the system or the audio signal, e.g., via clipping. Standards bodies differ in their recommendations for nominal level and headroom. Digital audio In digital audio, headroom is defined as the amount by which digital full scale (FS) exceeds the nominal level in decibels (dB). The European Broadcasting Union (EBU) specifies several nominal levels and resulting headroom for different applications. Analog audio In analog audio, headroom can mean low-level signal capabilities as well as the amount of extra power reserve available within the amplifiers that drive the loudspeakers. Alignment level Alignment level is an anchor point 9 dB below the nominal level, a reference level that exists throug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Reproduction
Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording. Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, which is then converted to a varying magnetic field by an electromagnet, which makes a representation of the sound as magnetized areas on a plastic tape with a magnetic coating on it. Analog sound reproduction is the reverse process, with a larger loudspeaker diaphragm c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A-weighting
A-weighting is a form of frequency weighting and the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. A-weighting is applied to instrument-measured sound levels in an effort to account for the relative loudness perceived by the human ear, as the ear is less sensitive to low audio frequencies. It is employed by arithmetically adding a table of values, listed by octave or third-octave bands, to the measured sound pressure levels in dB. The resulting octave band measurements are usually added (logarithmic method) to provide a single A-weighted value describing the sound; the units are written as dB(A). Other weighting sets of values – B, C, D and now Z – are discussed below. The curves were originally defined for use at different average sound levels, but A-weighting, though originally intended only for the measurement of low-level sounds (aro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Production Technology
In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges, allowing some to even hear ultrasounds. Definition Sound is defined as "(a) Oscillation in pressure, stress, particle displacement, particle velocity, etc., propagated in a medium with internal forces (e.g., elastic or viscous), or the superposition of such propagated oscillation. (b) Auditory s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Broadcast Engineering
Broadcast engineering or radio engineering is the field of electrical engineering, and now to some extent computer engineering and information technology, which deals with radio and television broadcasting. Audio engineering and RF engineering are also essential parts of broadcast engineering, being their own subsets of electrical engineering. Broadcast engineering involves both the studio and transmitter aspects (the entire airchain), as well as remote broadcasts. Every station has a broadcast engineer, though one may now serve an entire station group in a city. In small media markets the engineer may work on a contract basis for one or more stations as needed. Duties Modern duties of a broadcast engineer include maintaining broadcast automation systems for the studio and automatic transmission systems for the transmitter plant. There are also important duties regarding radio towers, which must be maintained with proper lighting and painting. Occasionally a station's eng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Engineering
Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound * Audio frequency, a frequency in the audio spectrum *Digital audio, representation of sound in a form processed and/or stored by computers or digital electronics *Audio, audible content (media) in audio production and publishing * Semantic audio, extraction of symbols or meaning from audio * Stereophonic audio, method of sound reproduction that creates an illusion of multi-directional audible perspective * Audio equipment Entertainment * AUDIO (group), an American R&B band of 5 brothers formerly known as TNT Boyz and as B5 * ''Audio'' (album), an album by the Blue Man Group * ''Audio'' (magazine), a magazine published from 1947 to 2000 * Audio (musician), British drum and bass artist * "Audio" (song), a song by LSD *"Audios", a song by Black Eyed Peas from ''Elevation'' Computing * HTML audio, identified by the tag See ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loudness War
The loudness war (or loudness race) is a trend of increasing audio levels in recorded music, which reduces audio fidelity and—according to many critics—listener enjoyment. Increasing loudness was first reported as early as the 1940s, with respect to mastering practices for 7-inch singles. The maximum peak level of analog recordings such as these is limited by varying specifications of electronic equipment along the chain from source to listener, including vinyl and cassette players. The issue garnered renewed attention starting in the 1990s with the introduction of digital signal processing capable of producing further loudness increases. With the advent of the compact disc (CD), music is encoded to a digital format with a clearly defined maximum peak amplitude. Once the maximum amplitude of a CD is reached, loudness can be increased still further through signal processing techniques such as dynamic range compression and equalization. Engineers can apply an increasingly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weighting Filter
A weighting filter is used to emphasize or suppress some aspects of a phenomenon compared to others, for measurement or other purposes. Audio applications In each field of audio measurement, special units are used to indicate a weighted measurement as opposed to a basic physical measurement of energy level. For sound, the unit is the phon (1 kHz equivalent level). Sound Sound has three basic components, the wavelength, frequency, and Speed of sound, speed. In sound measurement, we measure the loudness of the sound in decibels (dB). Decibels are logarithmic scale, logarithmic with 0 Dbx (noise reduction), dB as the reference. There are also a range of frequencies that sounds can have. Frequency is the number of times a sine wave repeats itself in a second. Normal auditory systems can usually hear between 20 and 20,000 Hz. When we measure sound, the measurement instrument takes the incoming auditory signal and analyzes it for these different features. Weighting fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rumble Measurement
A rumble is a continuous deep, resonant sound, such as the sound made by heavy vehicles or thunder. In the context of Sound recording and reproduction, audio reproduction rumble refers to a low frequency sound from the Bearing (mechanical), bearings inside a turntable. This is most noticeable in low quality turntables with ball bearings. Higher quality turntables use slide bearings, minimizing rumble. Some phono pre-amplifiers implement a rumble filter, in an attempt to remove the noise. A heavier platter can also help dampen this. Rumble measurement is carried out on turntables (for vinyl recordings) which tend to generate very low frequency noise originating from the centre Bearing (mechanical), bearing and from drive pulleys or belts, as well as from irregularities in the vinyl record, record disc itself. It can be heard as low-frequency noise and becomes a serious problem when playing records on audio systems with a good low-frequency response. Even when not audible, rumble ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise Measurement
In acoustics, noise measurement can be for the purpose of measuring environmental noise or measuring noise in the workplace. Applications include monitoring of construction sites, aircraft noise, road traffic noise, entertainment venues and neighborhood noise. One of the definitions of noise covers all "unwanted sounds". When sound levels reach a high enough intensity, the sound, whether it is wanted or unwanted, may be damaging to hearing. Environmental noise monitoring is the measurement of noise in an outdoor environment caused by transport (e.g. motor vehicles, aircraft, and trains), industry (e.g. machines) and recreational activities (e.g. music). The laws and limits governing environmental noise monitoring differ from country to country. At the very least, noise may be annoying or displeasing or may disrupt the activity or balance of human or animal life, increasing levels of aggression, hypertension and stress. In the extreme, excessive levels or periods of noise can have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loudness War
The loudness war (or loudness race) is a trend of increasing audio levels in recorded music, which reduces audio fidelity and—according to many critics—listener enjoyment. Increasing loudness was first reported as early as the 1940s, with respect to mastering practices for 7-inch singles. The maximum peak level of analog recordings such as these is limited by varying specifications of electronic equipment along the chain from source to listener, including vinyl and cassette players. The issue garnered renewed attention starting in the 1990s with the introduction of digital signal processing capable of producing further loudness increases. With the advent of the compact disc (CD), music is encoded to a digital format with a clearly defined maximum peak amplitude. Once the maximum amplitude of a CD is reached, loudness can be increased still further through signal processing techniques such as dynamic range compression and equalization. Engineers can apply an increasingly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-R 468 Noise Weighting
ITU-R 468 (originally defined in CCIR recommendation 468-4, therefore formerly also known as CCIR weighting; sometimes referred to as CCIR-1k) is a standard relating to noise measurement, widely used when measuring noise in audio systems. The standard, now referred to as ITU-R BS.468-4, defines a weighting filter curve, together with a quasi-peak rectifier having special characteristics as defined by specified tone-burst tests. It is currently maintained by the International Telecommunication Union who took it over from the CCIR. It is used especially in the UK, Europe, and former countries of the British Empire such as Australia and South Africa. It is less well known in the USA where A-weighting has always been used. M-weighting is a closely related filter, an offset version of the same curve, without the quasi-peak detector. Explanation The A-weighting curve was based on the 40 phon equal-loudness contour derived initially by Fletcher and Munson (1933). Originally inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equal-loudness Contour
An equal-loudness contour is a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon and is arrived at by reference to equal-loudness contours. By definition, two sine waves of differing frequencies are said to have equal-loudness level measured in phons if they are perceived as equally loud by the average young person without significant hearing impairment. The Fletcher–Munson curves are one of many sets of equal-loudness contours for the human ear, determined experimentally by Harvey Fletcher and Wilden A. Munson, and reported in a 1933 paper entitled "Loudness, its definition, measurement and calculation" in the ''Journal of the Acoustical Society of America''. Fletcher–Munson curves have been superseded and incorporated into newer standards. The definitive curves are those defined in ISO 226 from the International O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
