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49-439: The Absolute Sound ( TAS ) is an American audiophile magazine which reviews high-end audio equipment, along with recordings and comments on various music-related subjects. The Absolute Sound was founded in 1973 by Harry Pearson , who was its editor-in-chief and publisher. In the early years, TAS was a quarterly, digest-sized magazine and accepted no advertisements. During the 1970s and 1980s, TAS (along with Stereophile )

98-516: A Fourier transform to mathematically derive the impulse response of the room. From the impulse response, the reverberation time can be calculated. Using a two-port system allows reverberation time to be measured with signals other than loud impulses. Music or recordings of other sounds can be used. This allows measurements to be taken in a room after the audience is present. Under some restrictions, even simple sound sources like handclaps can be used for measurement of reverberation Reverberation time

147-553: A drop of 20 dB and multiply the time by 3, or a drop of 30 dB and multiply the time by 2. These are the so-called T20 and T30 measurement methods. The RT 60 reverberation time measurement is defined in the ISO 3382-1 standard for performance spaces, the ISO 3382-2 standard for ordinary rooms, and the ISO 3382-3 for open-plan offices, as well as the ASTM E2235 standard. The concept of reverberation time implicitly supposes that

196-459: A feature entitled HP's Workshop until his departure in 2012. The magazine is now published by NextScreen, LLC. of Round Rock, Texas . Audiophile An audiophile (from Latin : audīre , lit.   'to hear' + Greek : φίλος , romanized :  philos , lit.   'loving') is a person who is enthusiastic about high-fidelity sound reproduction . The audiophile seeks to achieve high sound quality in

245-467: A level recorder (a plotting device which graphs the noise level against time on a ribbon of moving paper). A loud noise is produced, and as the sound dies away the trace on the level recorder will show a distinct slope. Analysis of this slope reveals the measured reverberation time. Some modern digital sound level meters can carry out this analysis automatically. Several methods exist for measuring reverberation time. An impulse can be measured by creating

294-441: A listening room to reduce the amplitude of early reflections, and to deal with resonance modes. Other treatments are designed to produce diffusion, reflection of sound in a scattered fashion. Room treatments can be expensive and difficult to optimize. Headphones are regularly used by audiophiles. These products can be remarkably expensive, some over $ 10,000, but in general are much cheaper than comparable speaker systems. They have

343-420: A material is a number between 0 and 1 which indicates the proportion of sound which is absorbed by the surface compared to the proportion which is reflected back to the room. A large, fully open window would offer no reflection as any sound reaching it would pass straight out and no sound would be reflected. This would have an absorption coefficient of 1. Conversely, a thick, smooth painted concrete ceiling would be

392-466: A resurgence in high-res digital files. SACD can be stored as a DSD file, and DVD-Audio can be stored as an FLAC or ALAC file. FLAC is the most widely used digital format for high-res with up to 8 channels, a maximum depth of 32-bit, and 655,350 Hz sampling rate. Uncompressed formats such as WAV and AIFF files can store audio CDs without compression. A preamplifier selects among several audio inputs, amplifies source-level signals (such as those from

441-438: A sequence of less than approximately 50 ms. As time passes, the amplitude of the reflections gradually reduces to non-noticeable levels. Reverberation is not limited to indoor spaces as it exists in forests and other outdoor environments where reflection exists. Reverberation occurs naturally when a person sings, talks, or plays an instrument acoustically in a hall or performance space with sound-reflective surfaces. Reverberation

490-409: A sound source, a stopwatch and his ears, he measured the time from interruption of the source to inaudibility (a difference of roughly 60 dB). He found that the reverberation time is proportional to room dimensions and inversely proportional to the amount of absorption present. The optimum reverberation time for a space in which music is played depends on the type of music that is to be played in

539-399: A sufficiently loud noise (which must have a defined cut-off point). Impulse noise sources such as a blank pistol shot or balloon burst may be used to measure the impulse response of a room. Alternatively, a random noise signal such as pink noise or white noise may be generated through a loudspeaker, and then turned off. This is known as the interrupted method, and the measured result

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588-842: A turntable), and allows the listener to adjust the sound with volume and tone controls. Many audiophile-oriented preamplifiers lack tone controls. A power amplifier takes the "line-level" audio signal from the preamplifier and drives the loudspeakers . An integrated amplifier combines the functions of power amplification with input switching and volume and tone control. Both pre/power combinations and integrated amplifiers are widely used by audiophiles. Audiophile amplifiers are available based on solid-state ( semiconductor ) technology, vacuum-tube (valve) technology, or hybrid technology—semiconductors and vacuum tubes. Dedicated amplifiers are also commonly used by audiophiles to drive headphones, especially those with high impedance and/or low sensitivity, or electrostatic headphones . The loudspeaker's cabinet

637-490: A variety of accessories, including equipment racks, power conditioners , devices to reduce or control vibration , record cleaners, anti-static devices, phonograph needle cleaners, reverberation reducing devices such as speaker pads and stands, sound absorbent foam, and soundproofing . The interaction between the loudspeakers and the room ( room acoustics ) plays an important part in sound quality. Sound vibrations are reflected from walls, floor and ceiling, and are affected by

686-468: Is also a significant source of mistakes in automatic speech recognition . Dereverberation is the process of reducing the level of reverberation in a sound or signal. Reverberation time is a measure of the time required for the sound to "fade away" in an enclosed area after the source of the sound has stopped. When it comes to accurately measuring reverberation time with a meter, the term T 60 (an abbreviation for reverberation time 60 dB)

735-631: Is also continuing debate about the proper use of negative feedback in amplifier design. The audiophile community is scattered across many different platforms and communication methods. In person, one can find audiophiles at audio-related events such as music festivals, theaters , and concerts . The online audiophile community is even more widespread, with users on web forums and apps such as Facebook , Reddit , and others. These groups are self-identified audiophiles and will often contribute to their communities by mentoring new audiophiles, posting their current audio configurations, and sharing news related to

784-506: Is applied artificially by using reverb effects , which simulate reverb through means including echo chambers , vibrations sent through metal, and digital processing. Although reverberation can add naturalness to recorded sound by adding a sense of space, it can also reduce speech intelligibility , especially when noise is also present. People with hearing loss, including users of hearing aids , frequently report difficulty in understanding speech in reverberant, noisy situations. Reverberation

833-432: Is defined by the acoustic properties of the space). The equation does not take into account room shape or losses from the sound traveling through the air (important in larger spaces). Most rooms absorb less sound energy in the lower frequency ranges resulting in longer reverb times at lower frequencies. Sabine concluded that the reverberation time depends upon the reflectivity of sound from various surfaces available inside

882-428: Is frequency dependent: the length of the decay, or reverberation time, receives special consideration in the architectural design of spaces which need to have specific reverberation times to achieve optimum performance for their intended activity. In comparison to a distinct echo , that is detectable at a minimum of 50 to 100  ms after the previous sound, reverberation is the occurrence of reflections that arrive in

931-811: Is known as the enclosure . There are a variety of loudspeaker enclosure designs, including sealed cabinets ( acoustic suspension ), ported cabinets ( bass-reflex ), transmission line, infinite baffles, and horn-loaded. The enclosure plays a major role in the sound of the loudspeaker. Depending on the frequencies reproduced, the drivers that produce the sound are referred to as tweeters for high frequencies, midranges for middle frequencies, such as voice and lead instruments, and woofers for bass frequencies. Driver designs include dynamic , electrostatic , plasma , ribbon, planar, ionic, and servo-actuated. Drivers are made from various materials, including paper pulp, polypropylene, kevlar, aluminium, magnesium, beryllium, and vapour-deposited diamond. The direction and intensity of

980-434: Is known as the interrupted response. A two-port measurement system can also be used to measure noise introduced into a space and compare it to what is subsequently measured in the space. Consider sound reproduced by a loudspeaker into a room. A recording of the sound in the room can be made and compared to what was sent to the loudspeaker. The two signals can be compared mathematically. This two port measurement system utilizes

1029-458: Is measured in m³, and reverberation time RT 60 is measured in seconds . Eyring's reverberation time equation was proposed by Carl F. Eyring of Bell Labs in 1930. This equation aims to better estimate the reverberation time in small rooms with relatively large quantities of sound absorption, identified by Eyring as "dead" rooms. These rooms tend to have lower reverberation times than larger, more acoustically live rooms. Eyring's equation

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1078-431: Is necessarily subjective, often with subtle differences, leading to some more controversial audiophile techniques being based on pseudoscientific principles. An audio system typically consists of one or more source components, one or more amplification components, and (for stereo ) two or more loudspeakers . Signal cables (analog audio, speaker, digital audio etc.) are used to link these components. There are also

1127-511: Is similar in form to Sabine's equation, but includes modifications to logarithmically scale the absorption term. The units and variables within the equation are the same as those defined for Sabine's equation. The Eyring reverberation time is given by the equation: Eyring's equation was developed from first principles using an image source model of sound reflection, as opposed to Sabine's empirical approach. The experimental results obtained by Sabine generally agree with Eyring's equation since

1176-514: Is used. T 60 provides an objective reverberation time measurement. It is defined as the time it takes for the sound pressure level to reduce by 60  dB , measured after the generated test signal is abruptly ended. Reverberation time is frequently stated as a single value if measured as a wideband signal (20  Hz to 20 kHz). However, being frequency-dependent, it can be more precisely described in terms of frequency bands (one octave, 1/3 octave, 1/6 octave, etc.). Being frequency dependent,

1225-418: Is usually stated as a decay time and is measured in seconds. There may or may not be any statement of the frequency band used in the measurement. Decay time is the time it takes the signal to diminish 60 dB below the original sound. It is often difficult to inject enough sound into the room to measure a decay of 60 dB, particularly at lower frequencies. If the decay is linear, it is sufficient to measure

1274-522: The Journal of the Acoustical Society of America . He proposed to measure, not the power of the sound, but the energy, by integrating it. This made it possible to show the variation in the rate of decay and to free acousticians from the necessity of averaging many measurements. Sabine 's reverberation equation was developed in the late 1890s in an empirical fashion. He established a relationship between

1323-479: The T 60 of a room, its volume, and its total absorption (in sabins ). This is given by the equation: where c 20 is the speed of sound in the room (at 20 °C), V is the volume of the room in m , S total surface area of room in m , a is the average absorption coefficient of room surfaces, and the product Sa is the total absorption in sabins. The total absorption in sabins (and hence reverberation time) generally changes depending on frequency (which

1372-442: The acoustic equivalent of a mirror and have an absorption coefficient very close to 0. The Atlantic described reverberation as "arguably the oldest and most universal sound effect in music", used in music as early as 10th-century plainsong . Composers including Bach wrote music to exploit the acoustics of certain buildings. Gregorian chant may have developed in response to the long reverberation time of cathedrals , limiting

1421-536: The advantage of not requiring room treatment and being usable without requiring others to listen at the same time. However, many audiophiles still prefer speaker systems over headphones due to their ability to simulate an immersive, rounded sonic environment. Newer canalphones can be driven by the less powerful outputs found on portable music players. For music storage and playback, digital formats offer an absence of clicks, pops, wow , flutter , acoustic feedback , and rumble , compared to vinyl records. Depending on

1470-1262: The audio reproduction of recorded music, typically in a quiet listening space in a room with good acoustics . Audiophile values may be applied at all stages of music reproduction –the initial audio recording , the production process, the storage of sound data, and the playback (usually in a home setting). In general, the values of an audiophile are seen to be antithetical to the growing popularity of more convenient but lower-quality music, especially lossy digital file types like MP3 , lower-definition music streaming services , laptop or cell phone speakers, and low-cost headphones. The term high-end audio refers to playback equipment used by audiophiles, which may be bought at specialist shops and websites. High-end components include turntables , digital-to-analog converters , equalization devices, preamplifiers and amplifiers (both solid-state and vacuum tube ), loudspeakers (including horn , electrostatic and magnetostatic speakers), power conditioners , subwoofers , headphones , and acoustic room treatment in addition to room correction devices. Although many audiophile techniques are based on objective criteria that can be verified using techniques like ABX testing , perceived sound quality

1519-513: The audiophile community. Among the listeners themselves, audiophiles will commonly differentiate community members between "golden eared" and "wooden eared" individuals. Those who are deemed as having "golden ears" are people who can accurately express the description of a sound or sonic environment, whereas those with "wooden ears" are implied to be untrained in listening and needing more guidance or assistance. These labels are not permanent, however, and people within these two groups can move between

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1568-475: The core source, amplification, and speaker products. Examples of these accessories include speaker cables, component interconnects, stones, cones, CD markers, and power cables or conditioners. One of the most notorious "tweakers" was Peter Belt , who introduced numerous eccentric innovations that included a £500 "quantum clip" that consisted of a crocodile clip with a short length of copper wire attached. Audio societies Reverberation Reverberation

1617-514: The decay rate of the sound is exponential, so that the sound level diminishes regularly, at a rate of so many dB per second. It is not often the case in real rooms, depending on the disposition of reflective, dispersive and absorbing surfaces. Moreover, successive measurement of the sound level often yields very different results, as differences in phase in the exciting sound build up in notably different sound waves. In 1965, Manfred R. Schroeder published "A new method of Measuring Reverberation Time" in

1666-784: The early 1990s, CDs were the most common source of high-quality music. Nevertheless, turntables , tonearms, and magnetic cartridges are still used, despite the difficulties of keeping records free from dust and the delicate set-up associated with turntables. The 44.1 kHz sampling rate of the CD format, in theory, restricts CD information losses to above the theoretical upper-frequency limit of human hearing – 20 kHz. Nonetheless, newer formats such as FLAC, ALAC, DVD-Audio and Super Audio Compact Disc (SACD) allow for sampling rates of 88.2 kHz, 96 kHz or even 192 kHz. Higher sample rates allow fewer restrictions on filter choices in playback components, and some audiophiles upsample from

1715-420: The format, digital can have a higher signal-to-noise ratio , a wider dynamic range , less total harmonic distortion , and a flatter and more extended frequency response . The digital recording and playback processes may include degradations not found in the analog processes, such as timing jitter and distortions associated with band limiting filter choices. Vinyl records remain popular and discussion about

1764-571: The groups interchangeably, often depending on the judgement of others within the community. There is substantial controversy on the subject of audiophile components; many have asserted that the occasionally high cost produces no measurable improvement in audio reproduction. For example, skeptic James Randi , through his foundation One Million Dollar Paranormal Challenge , offered a prize of $ 1 million to anyone able to demonstrate that $ 7,250 audio cables "are any better than ordinary audio cables". In 2008, audio reviewer Michael Fremer attempted to claim

1813-440: The hall. If the reflection is coherent, the reverberation time of the hall will be longer; the sound will take more time to die out. The reverberation time RT 60 and the volume V of the room have great influence on the critical distance d c (conditional equation): where critical distance d c {\displaystyle d_{c}} is measured in meters, volume V {\displaystyle V}

1862-415: The output of a loudspeaker, called dispersion or polar response, has a large effect on its sound. Various methods are employed to control the dispersion. These methods include monopolar, bipolar, dipolar, 360-degree, horn, waveguide, and line source. These terms refer to the configuration and arrangement of the various drivers in the enclosure. The positioning of loudspeakers in the room strongly influences

1911-421: The perceived spectral structure of a sound but does not alter the pitch. Basic factors that affect a room's reverberation time include the size and shape of the enclosure as well as the materials used in the construction of the room. Every object placed within the enclosure can also affect this reverberation time, including people and their belongings. Historically, reverberation time could only be measured using

1960-511: The prize, and said that Randi declined the challenge. Randi said that the cable manufacturer Pear Cables was the one who withdrew. Another commonly referenced study done by Philip Greenspun and Leigh Klotz of the Massachusetts Institute of Technology found that although test subjects were able to distinguish between high fidelity, "expensive" cables versus common use cables, there was no statistically significant preference between

2009-566: The relative merits of analog and digital sound continues (see Comparison of analog and digital recording ). Note that vinyl records may be mastered differently from their digital versions, and multiple digital remasters may exist. In the amplification stage, vacuum-tube electronics remain popular, despite most other applications having since abandoned tubes for solid state amplifiers. Vacuum-tube amplifiers often have higher total harmonic distortion , require rebiasing, are less reliable, generate more heat, are less powerful, and cost more. There

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2058-439: The reverberation time measured in narrow bands will differ depending on the frequency band being measured. For precision, it is important to know what ranges of frequencies are being described by a reverberation time measurement. In the late 19th century, Wallace Clement Sabine started experiments at Harvard University to investigate the impact of absorption on the reverberation time. Using a portable wind chest and organ pipes as

2107-717: The room's contents. Room dimensions can create standing waves at particular (usually low) frequencies. There are devices and materials for room treatment that affect sound quality. Soft materials, such as draperies and carpets, can absorb higher frequencies, whereas hard walls and floors can cause excess reverberation. Audiophiles play music from a variety of sources including phonograph records , compact discs (CDs), and digital audio files that are either uncompressed or are losslessly compressed , such as FLAC , DSD , Windows Media Audio 9 Lossless and Apple Lossless (ALAC), in contrast to lossy compression , such as in MP3 encoding. From

2156-690: The sound experience. Loudspeaker output is influenced by interaction with room boundaries, particularly bass response, and high-frequency transducers are directional, or "beaming". Audiophiles use a wide variety of accessories and fine-tuning techniques, sometimes referred to as "tweaks", to improve the sound of their systems. These include power conditioner filters to "clean" the electricity, equipment racks to isolate components from floor vibrations, specialty power and audio cables, loudspeaker stands (and footers to isolate speakers from stands), and room treatments. There are several types of room treatment. Sound-absorbing materials may be placed strategically within

2205-546: The source rate to higher rates to achieve different filter properties. CD audio signals are encoded in 16-bit values. Higher-definition consumer formats such as HDCD -encoded CDs, DVD-Audio, and SA-CD contain 20-bit, 24-bit and even 32-bit audio streams. With more bits, more dynamic range is possible; 20-bit dynamic range is theoretically 120 dB—the limit of most consumer electronic playback equipment. SACDs and DVD-Audio have up to 5.1 to 6.1 surround sound. Although both high-res optical formats have failed, there has been

2254-511: The space. Rooms used for speech typically need a shorter reverberation time so that speech can be understood more clearly. If the reflected sound from one syllable is still heard when the next syllable is spoken, it may be difficult to understand what was said. "Cat", "cab", and "cap" may all sound very similar. If on the other hand the reverberation time is too short, tonal balance and loudness may suffer. Reverberation effects are often used in studios to add depth to sounds. Reverberation changes

2303-897: The two cables. Greenspun and Klotz expect that critics of the study will point to the fact that this experiment was not done as a double-blind test , but this critique has a counter in that the study participants felt as though the experiment solely isolated the subjects' opinions on sound quality and nothing more. There is disagreement on how equipment testing should be conducted and its utility. Audiophile publications frequently describe differences in quality which are not detected by standard audio system measurements and double blind testing , claiming that they perceive differences in audio quality which cannot be measured by current instrumentation, and cannot be detected by listeners if listening conditions are controlled , but without providing an explanation for those claims. Criticisms usually focus on claims around so-called "tweaks" and accessories beyond

2352-758: The two formulae become identical for very live rooms, the type in which Sabine worked. However, Eyring's equation becomes more valid for smaller rooms with large quantities of absorption. As a result, the Eyring equation is often implemented to estimate the reverberation time in recording studio control rooms or other critical listening environments with high quantities of sound absorption. The Sabine equation tends to over-predict reverberation time for small rooms with high amounts of absorption. For this reason, reverberation time calculators available for smaller recording studio environments, such as home recording studios, often utilize Eyring's equation. The absorption coefficient of

2401-475: Was influential in the audiophile industry. Pearson is credited as being the most important figure in the rise of High-End audio . Until the mid- to late 1990s, Pearson owned and directed all rights to TAS. The magazine was published by Pearson Publishing Inc., which also published a sister high-end video review magazine published quarterly called The Perfect Vision . Pearson remained the chairman of its editorial advisory board until 2006 and regularly contributed

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