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Audio system measurements are made for several purposes. Designers take measurements so that they can specify the performance of a piece of equipment. Maintenance engineers make them to ensure equipment is still working to specification, or to ensure that the cumulative defects of an audio path are within limits considered acceptable. Some aspects of measurement and specification relate only to intended usage. For example, magnetic tape speeds and types, interface specifications, or power output. Image File history File links Please see the file description page for further information. ...
It has been suggested that this article or section be merged with Audio system measurements. ...
Compact audio cassette Magnetic tape is a non-volatile storage medium consisting of a magnetic coating on a thin plastic strip. ...
Others are intended as an index of the quality, or 'fidelity', of reproduction perceivable by a human. It is important that such measurements accomodate psychoacoustic principles, so that they truly measure the system in a way that is 'subjectively valid'. Humans don't hear very low levels of sound, so there is reason to be concerned about the the precise nature of noise at very low levels, than at higher levels. Psychoacoustics is the study of subjective human perception of sounds. ...
Subjectivity and frequency weighting
Measurements based on psychoachoustics, such as the measurement of noise, often use a weighting filter. It is well-established that human hearing is more sensitive to some frequencies than others, as demonstrated by equal-loudness contours, but it is not well appreciated that these contours vary depending on the type of sound. The measured curves for pure tones, for instance, are different from those for random noise. The ear also responds less to short bursts, below 100 to 200 ms, than to continuous sounds [1] such that a quasi-peak detector has been found to give the most representative results when noise contains click or bursts, as is often the case for noise in digital systems. [2] For these reasons a set of subjectively valid measurement techniques have been devised and incorporated into BS, IEC, EBU and ITU standards. These newer methods of audio quality measurement are used by broadcast engineers throughout most of the world, as well as by some audio professionals, though the older A-weighting standard for continuous tones is still commonly used by others. [1] Subjectively valid methods came to prominence in consumer audio in the UK and Europe in the 1970s, when the introduction of compact cassette tape and DBX and Dolby noise reduction techniques revealed the unsatisfactory nature of many basic engineering measurements. The specification of weighted CCIR-468 quasi-peak noise, and weighted quasi-peak wow and flutter became particulary widely used and attempts were made to find more valid methods for distortion measurement. In science, and especially in physics and telecommunication, noise is fluctuations in and the addition of external factors to the stream of target information (signal) being received at a detector. ...
The A, B, C, and D weighting curves A weighting filter is used to emphasise some aspects of a phenomenon over others, for measurement or other purposes. ...
Hearing, or audition, is one of the traditional five senses, and refers to the ability to detect sound. ...
An equal-loudness contour is a measure of sound pressure (dB SPL) vs. ...
Quasi-peak means not quite peak, or aiming towards peak but not actually peak. The term is commonly used when referring to electronic detectors or rectifiers. ...
The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ...
<marquee bgcolor=white><text color=lime> sup --> The European Broadcasting Union (EBU), known in French as LUnion Européenne de Radio-Télévision (UER), and unrelated to the European Union, was formed on 12 February 1950 by 23 broadcasting organisations from Europe and the Mediterranean at a conference...
This article is about the location. ...
It has been suggested that this article or section be merged with Audio system measurements. ...
The A-weighting curve is one of a family of curves defined in IEC179 and various other standards for use in sound level meters. ...
The Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply a tape. ...
dbx or DBX refers to: David Brockie Experience dbx, Inc. ...
Dolby NR is a noise reduction system developed by Dolby Laboratories for use in analogue magnetic tape recording. ...
The ITU-R 468-weighting curve (originally defined in CCIR recommendation 468) is widely used when measuring noise in audio systems, especially in the UK, Europe, and former countries of the British Empire such as Australia and South Africa. ...
Wow and flutter measurement measurement is carried out on audio tape machines or cassette recorders and players in order to quantify the amount of frequency wobble (caused by tape speed fluctuations) present in subjectively valid terms. ...
Distortion measurement is one of the measurements made on audio systems and equipment in order to assess their quality of reproduction. ...
No single measurement can assess audio quality. Instead, it is usual to take a series of measurements to test for the various types of degradation that can reduce fidelity. Thus, when testing an analogue tape machine it is necessary to test for wow and flutter and tape speed variations over longer periods, as well as for distortion and noise. When testing a digital system, testing for speed variations is normally considered unnecessary given the nearly ubiquitious accurate clocks in digital circuitry, but testing for aliasing and timing jitter is often desirable, as these have caused audible degradation in many systems. The claim is often made that different methods of measuring noise, or distortion, are better suited to different items of equipment is not widely believed among professional audio engineers. Wow and flutter may refer to: Wow (recording) and flutter, two forms of noise which emanate from cassette tapes; The title of a critically-acclaimed single, from the 1994 recording by Stereolab, entitled Mars Audiac Quintet; and Wow & Flutter, an indie rock band from Portland, Oregon. ...
In statistics, signal processing, computer graphics and related disciplines, aliasing is an effect that causes different continuous signals to become indistinguishable (or aliases of one another) when sampled. ...
In telecommunication, jitter is an abrupt and unwanted variation of one or more signal characteristics, such as the interval between successive pulses, the amplitude of successive cycles, or the frequency or phase of successive cycles. ...
Once subjectively valid methods have been shown to correlate well with listening tests over a wide range of conditions, then such methods are generally adopted as preferred. But it's important to realise that engineering methods are not always sufficient to when comparing like with like. One CD player, for example, might have higher measured noise than another CD player when measured RMS, or even A-weighted RMS, yet sound quieter and measure lower when 468-weighting is used. This could be because it has more noise at high frequencies, or even at frequencies beyond 20 kHz, both of which are less important since human ears are less sensitive to them. See noise shaping.) This effect is how Dolby B works and why it was introduced. Cassette noise, which was predominately high frequency and unavoidable given the small size and speed of the recorded track could be made subjectively much less important. The noise sounded 10 dB quieter, but failed to measure much better unless 468-weighting was used rather than A-weighting. Similar to dither, noise shaping is a bit reduction technique used to minimize quantization error. ...
Dolby NR is a noise reduction system developed by Dolby Laboratories for use in analogue magnetic tape recording. ...
Measurable performance
Analog electrical - Frequency response
- The signal should be passed at least over the audible range (usually quoted as 20 Hz to 20 kHz) with no significant peaks or dips. The human ear can discern differences in level of about 3 dB in some frequency ranges, so peaks and troughs must be less than this. Much modern equipment is capable of less than ±1 dB variation over the entire audible frequency range. Rapid variations over a small frequency range (ripple), or very steep rolloffs are considered undesirable as they can correspond to resonances associated with energy storage which produce delayed echoes and hence colouration, or decreased quality, of the sound.
- Total harmonic distortion (THD)
- In music material, there are distinct tones, and some kinds of distortion involve spurious double or triple the frequencies of those tones. Such harmonically related distortion is called harmonic distortion. For high fidelity, this is usually expected to be < 1% for electronic devices; mechanical elements such as loudspeakers usually have inescapable higher levels. Low distortion is relatively easy to achieve in electronics with use of negative feedback, but the use of high levels of feedback in this manner has been the topic of much controversy among audiophiles — see electronic amplifier. Essentially all loudspeakers produce more distortion than electronics, and 1–5% distortion is not unheard of at moderately loud listening levels. Human ears are less sensitive to distortion in the bass frequencies, and levels are usually expected to be under 10% at loud playback. Distortion which creates only even-order harmonics for a sine wave input is sometimes considered less bothersome than odd-order distortion.
- Output power
- Output power for amplifiers is ideally measured and quoted as maximum sinewave (ie, RMS) power output per channel, at a specified distortion level at a particular load, which by convention and government regulation, is considered the most meaningful measure of power available on music signals, though real, non-clipping music has a high peak-to-average ratio, and usually averages well below the maximum possible. The commonly given measurement of PMPO (peak music power out) is largely meaningless and often used in marketing literature; in the late 1960s there was much controversy over this point and the US Government (FTA) required that RMS figures be quoted for all high fidelity equipment. Music power has been making a comeback in recent years. See also Audio power.
- Power specifications require the load impedance to be specified, and in some cases two figures will be given (for instance, a power amplifier for loudspeakers will be typically measured at 4 and 8 ohms). Any amplifier will drive more current to a lower impedance load. For example, it will deliver more power into a 4-ohm load, as compared to 8-ohm, but it must not be assumed that it is capable of sustaining the extra current unless it is specified so. Power supply limitations may limit high current performance.
- Intermodulation distortion (IMD)
- Distortion which is not harmonically related to the signal being amplified is intermodulation distortion. It is a measure of the level of spurious signals resulting from unwanted combination of different frequency input signals. This effect results form non-linearities in the system. Again, sufficiently high levels of negative feedback can reduce this effect, as for instance in an amplifier. Many believe it is better to design electronics to minimise feedback levels. Low intermodulation equipment is difficult to design while meeting other high accuracy requirments. Intermodulation in speaker drivers is, as with harmonic distortion, almost always larger than in most electronics. Reducing cone excursion is one way to reduce intermodulation distrotion as is designing and building crossovers so that out of band signals are reduced quickly. This raises other problems related to crossover designs and is an example of the tradeoffs which must be made in high quality audio design.
- Noise
- The level of unwanted noise generated by the system itself, or by interference from external sources added to the signal. Hum usually refers to noise only at power line frequencies (as opposed to broadband white noise), which is introduced through induction of power line signals into the inputs of gain stages. Or from inadequately regulated power supplies.
- Crosstalk
- The introduction of noise (from another signal channel) caused by stray inductance or capacitance between components or lines. Crosstalk reduces, sometimes noticeablly, separation between channels (eg, in a stereo system). It is given in dB relative to a nominal level of signal in the path receiving interference. Crosstalk is normally only a problem in equipment in which several channels are handled in the same chassis.
- Common-mode rejection ratio (CMRR)
- All electronic equipment with inputs is susceptible to this problem. In balanced audio systems, there are equal and opposite signals (difference-mode) in inputs, and any interference imposed on both leads will be subtracted, canceling out that interference (ie, the common-mode). CMRR is a measure of a system's ability to ignore any such interference and especially hum which arises at its input. It is generally only significant with long lines on an input, or when soem kinds of ground loop problems exist. Unbalanced inputs do not have common mode resistance; induced noise on their inputs appears directly as noise or hum.
- Dynamic range and Signal-to-noise ratio (SNR)
- The difference between the maximum level a component can accomodate and the noise level it produces. Input noise is not counted in this measurement. It is measured in dB.
- Dynamic range refers to the ratio of maximum to mimimum loudness in a given signal source (eg, music or programme material), and this measurement also quantifies the maximum dynamic range an audio system can carry. This is the ratio (usually expressed in dB) between the noise floor of the device with no signal and the maximum signal (usually a sine wave) that can be output at a specified (low) distortion level.
- Signal-to-noise ratio (SNR), however, is the ratio between the noise floor and an arbitrary reference level or alignment level. In "professional" recording equipment, this reference level is usually +4 dBu (IEC 60268-17), though sometimes 0 dBu (UK and Europe - EBU standard Alignment level). 'Test level', 'measurement level' and 'line-up level' mean different things, often leading to confusion. In "consumer" equipment, no standard exists, though −10 dBV and −6 dBu are common.
- Different media characteristically exhibit different amounts of noise and headroom. Though the values vary widely between units, a typical analogue cassette might give 60 dB, a CD almost 100 dB. Most modern quality amplifiers have >110 dB dynamic range, which approaches that of the human ear, usually taken as around 160 dB. See Programme levels.
- Phase distortion, Group delay, and Phase delay
- A perfect audio component will maintain the phase coherency of a signal over the full range of frequencies. Phase distortion can be extremely difficult to reduce or eliminate. The human ear is largely insensitive to phase distortion, though it is equisitly sensitive to relative phase relationships within heard sounds. For many this figure lacks importance; however, there are many who argue its significance. Multi-driver loudspeaker systems have complex phase distortions, caused by crossovers, by driver placment relative to other drivers, and by internal driver characteristics.
- Transient distortion
- A system may have low distortion for a steady-state signal, but not on sudden transients. This problem can be traced to amplifier power supplies in some instances, to insufficient high frequency performance in amplifiers, to negative feedback in amplifiers, or in loudspeakers to the mass and resonances of drivers and enclosures. Related measurements are slew rate and rise time. Transient distortion can be hard to measure. Many otherwise good power amplifier designs have foudn to have inadequate slew rates, by modern standards. Most loudspeakers generate significant amounts of transient distortion, though some designs are less prone to this (e.g. electrostatic loudspeakers, plasma arc tweeters, ribbon tweeters).
- Damping factor
- A higher number is generally thought better. This is a measure of how well a power amplifier can control the undesired motion of a loudspeaker driver due largely to mechanical reactance. The amplifier must be able to damp out resonances caused by the mechanical motions (eg, inertia) of the moving parts of the speaker. For the common voice coil drivers, this essentially involves ensuring that the output impedance of the amplifier is close to zero. Damping factor is actually a relative way of specifying the output impedance of an amplifier with a particular load. It is affected by the cables used to connect the speakers to the amplifier, and by the amount of negative feedback especially in solid state amplifiers.
Frequency response is the measure of any systems response to frequency, but is usually used in connection with electronic amplifiers and similar systems, particularly in relation to audio signals. ...
The hertz (symbol: Hz) is the SI unit of frequency. ...
A kilohertz (kHz) is a unit of frequency equal to 1,000 hertz (1,000 cycles per second). ...
The decibel (dB) method of calculation , that uses a logarithm to allow very large or very small relations to be represented with a conveniently small number (similar to scientific notation). ...
Colouration refers to a property of loudspeakers that detracts from realistic reproduction. ...
The total harmonic distortion, or THD, of a signal is a measurement of the harmonic distortion present and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental. ...
High Fidelity is also the title of a book by Nick Hornby and a film directed by Stephen Frears, based upon Hornbys book. ...
Negative feedback (shortened to NFB) is a type of feedback in which the system responds in an opposite direction to the perturbation. ...
This article or section may contain original research or unverified claims. ...
It has been suggested that Rf power amplifier be merged into this article or section. ...
The term sine power is used in the specification or measurement of audio amplifiers or loudspeakers. ...
In trigonometry, an ideal sine wave is a waveform whose graph is identical to the generalized sine function y = Asin[ω(x − α)] + C, where A is the amplitude, ω is the angular frequency (2π/P where P is the wavelength), α is the phase shift, and C...
In mathematics, the root mean square or rms is a statistical measure of the magnitude of a varying quantity. ...
In physics, power (symbol: P) is the rate at which work is performed or energy is transferred. ...
Look up clipping in Wiktionary, the free dictionary. ...
The term sine power is used in the specification or measurement of audio amplifiers or loudspeakers. ...
The input impedance or load impedance of a circuit or electronic device is the impedance actually experienced by a signal which is connected to it. ...
A multimeter can be used to measure resistance in ohms Several resistors. ...
Intermodulation distortion: Nonlinear distortion characterized by the appearance, in the output of a device, of frequencies that are linear combinations of the fundamental frequencies and all harmonics present in the input signals. ...
In science, and especially in physics and telecommunication, noise is fluctuations in and the addition of external factors to the stream of target information (signal) being received at a detector. ...
A hum is a sound with a particular timbre (or sound quality), usually a monotone or with slightly varying tones, often produced by machinery in operation or by insects in flight. ...
White noise spectrum White noise( ) is a random signal (or process) with a flat power spectral density. ...
In telecommunication, the term crosstalk (XT) has the following meanings: 1. ...
Common mode rejection ratio (CMRR) is a measure of the capability of an instrument, ie. ...
Balanced audio connections are extremely important in sound recording and production because they allow for the use of very long cables with reduced introduction of outside noise. ...
A hum is a sound with a particular timbre (or sound quality), usually a monotone or with slightly varying tones, often produced by machinery in operation or by insects in flight. ...
The term ground loop has more than one meaning: In electrical and electronic engineering, a ground loop refers to an unwanted current that flows in a conductor connecting two points that are nominally at the same potential, for example ground potential, but are actually at different potentials. ...
Dynamic range is a term used frequently in numerous fields to describe the ratio between the smallest and largest possible values of a changeable quantity. ...
Signal-to-noise ratio (often abbreviated SNR or S/N) is an electrical engineering concept defined as the ratio of a signal power to the noise power corrupting the signal. ...
The decibel (dB) method of calculation , that uses a logarithm to allow very large or very small relations to be represented with a conveniently small number (similar to scientific notation). ...
In trigonometry, an ideal sine wave is a waveform whose graph is identical to the generalized sine function y = Asin[ω(x − α)] + C, where A is the amplitude, ω is the angular frequency (2π/P where P is the wavelength), α is the phase shift, and C...
The Alignment level in an audio signal chain or on an audio recording is an anchor point that represents a reasonable or typical level. ...
Noise measurement is carried out in various fields. ...
Headroom (band) is the name of a band HeadRoom is the name of a headphone equipment company Headroom is a term used in signal processing (audio, data, etc) to refer to the maximum allowable signal level before compression or distortion. ...
The Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply a tape. ...
The decibel (dB) method of calculation , that uses a logarithm to allow very large or very small relations to be represented with a conveniently small number (similar to scientific notation). ...
This article or section does not cite its references or sources. ...
Bat ears come in different sizes and shapes The ear is the sense organ that detects sound. ...
Programme levels are important in Audio if listeners to CDs, Radio and Television are to get the best experience. ...
Phase distortion: Distortion that occurs when (a) the phase-frequency characteristic is not linear over the frequency range of interest, , the phase shift introduced by a circuit or device is not directly proportional to frequency, or (b) the zero-frequency intercept of the phase-frequency characteristic is not 0 or...
In physics, and in particular in optics, the study of waves and digital signal processing, the term group delay has the following meanings: 1. ...
In LTI system theory, control theory, and in digital or analog signal processing, the relationship between the input signal, x(t), to output signal, y(t), of an LTI system is governed by: or where and . Here h(t) is the impulse response of the LTI system and X(s...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
In electronics, the slew rate is a nonlinear effect in amplifiers. ...
In electronics, when approximating a voltage or current step function, rise time (also risetime) refers to the time required for a signal to change from a specified low value to a specified high value. ...
“Loudspeaker†redirects here. ...
Schematic showing an electrostatic speakers construction and its connections. ...
A plasma arc loudspeaker or plasma-dynamic loudspeaker is a loudspeaker that creates sound by varying air pressure through a corona discharge or electric arc. ...
The damping factor in an electrical circuit gives the ratio of the impedances of two electronic devices, the load impedance (input impedance) and the source impedance (output impedance). ...
Generally, an amplifier is any device that uses a small amount of energy to control a larger amount of energy. ...
“Loudspeaker†redirects here. ...
This article is about resonance in physics. ...
The principle of inertia is one of the fundamental laws of classical physics which are used to describe the motion of matter and how it is affected by applied forces. ...
The output impedance, source impedance, or internal impedance of an electronic device is the opposition exhibited by its output terminals to the flow of an alternating current (AC) of a particular frequency as a result of resistance, induction and capacitance. ...
Mechanical - Wow and flutter
- These measurements are related to physical motion in a component, largely the drive mechanism of analogue media, such as vinyl records and magnetic tape. "Wow" is slow speed (a few Hz) variation, caused by longer term drift of the drive motor speed, whereas "flutter" is faster speed (a few tens of Hz) variations, usually caused by mechanical defects such as out-of-roundness of the capstan of a tape transport mechanism. The measurement is given in % and a lower number is better.
- Rumble
- The measure of the low frequency (many tens of Hz) noise contributed by the turntable of an analogue playback system. It is caused by imperfect bearings, by uneven motor windings, by vibrations in driving bands in some turntables, by room vibrations (eg, from traffic) which is transmitted by the turntable mounting and so to the phono cartridge. A lower number is better.
Wow is a relatively slow form of flutter (pitch variation) which can affect both gramophone records and audio cassettes. ...
Flutter: In electronics, rapid variation of signal parameters, such as amplitude, phase, and frequency. ...
An analog or analogue signal is an allergy continuous in both time and amplitude. ...
A gramophone record, (also phonograph record - often simply record) is an analog sound recording medium: a flat disc rotating at a constant angular velocity, with inscribed spiral grooves in which a stylus or needle rides. ...
Compact audio cassette Magnetic tape is a non-volatile storage medium consisting of a magnetic coating on a thin plastic strip. ...
Nautical capstan A capstan is a rotating machine used to control or apply force to another element, usually linear. ...
Edison cylinder phonograph ca. ...
Digital Note that digital systems do not suffer from many of these effects at a signal level, though the same processes occur in the circuitry, since the data being handled is symbolic. As long as the symbol survives the transfer between components, and can be perfectly regenerated (eg, by pulse shaping techniques) the data itself is perfectly maintained. The data is typically buffered in a memory, and is clocked out by a very precise crystal oscillator. The data usually does not degenerate as it passes through many stages, because each stage regenerates new symbols for transmission. In synchronous digital electronics, such as most computers, a clock signal is a signal used to coordinate the actions of two or more circuits. ...
A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. ...
But digital systems have their own problems. Digitizing adds noise which is measurable, and which depends on the resolution ('number of bits") of the system, regardless of other quality issues. Clock timing errors (jitter) result in non-linear distortion of the signal. The quality measurement for a digital system centers on the probability of an error in transmission or reception. Otherwise the quality of the system is defined more by design intent (ie, specifications) than measurements, such as the sample rate and bit depth. In general, digital systems are much less prone to error than analog systems. However, nearly all digital systems contain analog inputs and/or outputs, and certainly all of those which interact with the analog world do so. These analog components of the digital system can suffer analog effects and potentially compromise the integrity of a well designed digital system. Quantization noise is a noise error introduced by the analogue to digital conversion (ADC) process in telecommunication systems and signal processing. ...
In telecommunication, jitter is an abrupt and unwanted variation of one or more signal characteristics, such as the interval between successive pulses, the amplitude of successive cycles, or the frequency or phase of successive cycles. ...
The sampling frequency or sampling rate defines the number of samples per second taken from a continuous signal to make a discrete signal. ...
Color depth is a computer graphics term describing the number of bits used to represent the color of a single pixel in a bitmapped image or video frame buffer. ...
- Jitter
- A measurement of the variation in period between clock cycles, which should theoretically be exactly the same period. Less jitter is better.
- Sample rate
- A specification of the rate at which measurements are taken of the analog signal. This is measured in samples per second, or hertz. A higher sampling rate allows a greater total bandwidth or flatband frequency response. It can also reduce the effects of jitter.
- Bit depth
- A specification of the accuracy of each measurement. For example, a 3-bit system would be able to measure 23 = 8 different levels, so it would round the actual level at each point to the nearest representable. Typical values for audio are 8-bit, 16-bit, 24-bit, and 32-bit. The bit depth determines the theoretical maximum signal-to-noise ratio or dynamic range for the system. It is common for devices to create more noise than the minimum possible noise floor, however. Sometimes this is done intentionally; dither noise is added to decrease the negative effects of quantization noise by converting it into a higher level of uncorrelated noise.
- To calculate the maximum theoretical dynamic range of a digital system, find the total number of levels in the system. Dynamic Range = 20·log(# of different levels). Note: the log function has a base of 10. Example: An 8-bit system has 256 different possibilities, from 0 – 255. The smallest signal is 1 and the largest is 255. Dynamic Range = 20·log(255) = 48 dB.
- Sample accuracy/synchronization
- Not as much a specification as an ability. Since independent digital audio devices are each run by their own crystal oscillator, and no two crystals are exactly the same, the sample rate will be slightly different. This will cause the devices to drift apart over time. The effects of this can vary. If one digital device is used to monitor another digital device, this will cause dropouts in the audio, as one device will be producing more or less data than the other per unit time. If two independent devices record at the same time, one will lag the other more and more over time. This effect can be circumvented with a wordclock synchronization.
- Linearity
- Differential non-linearity and integral non-linearity are two measurements of the accuracy of an analog-to-digital converter. Basically, they measure how close the threshold levels for each bit are to the theoretical equally-spaced levels.
In telecommunication, jitter is an abrupt and unwanted variation of one or more signal characteristics, such as the interval between successive pulses, the amplitude of successive cycles, or the frequency or phase of successive cycles. ...
The sampling frequency or sampling rate defines the number of samples per second taken from a continuous signal to make a discrete signal. ...
The hertz (symbol: Hz) is the SI unit of frequency. ...
Color depth is a computer graphics term describing the number of bits used to represent the color of a single pixel in a bitmapped image or video frame buffer. ...
Dither is a form of noise, or erroneous signal or data which is deliberately added to sample data for the purpose of minimizing quantization error. ...
Quantization noise is a noise error introduced by the analogue to digital conversion (ADC) process in telecommunication systems and signal processing. ...
A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. ...
The English-language WordClock provides a precise, up-to-the-minute estimate of the number of words currently in use in the English language. ...
An analog-to-digital converter (abbreviated ADC, A/D or A to D) is an electronic circuit that converts continuous signals to discrete digital numbers. ...
Unquantifiable? Some audiophiles have postulated that the present set of audio measurements, as exemplified by the above list, does not fully represent all that is significant in accurate music reproduction, and instead represents only those aspects which are relatively easy and cost-effective to measure with our current technology. Given the complexity and sophistication of human hearing and perception, it is felt that some consideration should be given to the possibility that there may be aspects of music reproduction that have yet to be identified. This article or section may contain original research or unverified claims. ...
Hearing, or audition, is one of the traditional five senses, and refers to the ability to detect sound. ...
All of the above measurements are quantitative, not qualitative. Subjectivists claim that listening tests are more appropriate for appraising the quality of an audio system than measuring the accuracy with which it can reproduce a waveform. A scale for measuring mass A quantitative property is one that exists in a range of magnitudes, and can therefore be measured. ...
Qualitative is an important qualifier in the following subject titles: Qualitative identity Qualitative marketing research Qualitative method Qualitative research THE BIG J This is a disambiguation page — a list of pages that otherwise might share the same title. ...
See also It has been suggested that this article or section be merged with Audio system measurements. ...
High Fidelity is also the title of a book by Nick Hornby and a film directed by Stephen Frears, based upon Hornbys book. ...
High Fidelity is also the title of a book by Nick Hornby and a film directed by Stephen Frears, based upon Hornbys book. ...
This article or section may contain original research or unverified claims. ...
Sound waves Variations in air pressure against the ear drum, and the subsequent physical and neurological processing and interpretation, give rise to the experience called sound. Most sound that people recognize as musical is dominated by periodic or regular vibrations rather than non-periodic ones (called a definite pitch), and...
References - ^ Moore, Brian C. J., An Introduction to the Psychology of Hearing, 2004, 5th ed. p137, Elsevier Press
- ^ BBC Research Report EL17, The Assessment of Noise in Audio Frequency Circuits, 1968.
External links - Explanation of INL/DNL measurements
- Headphones-guru - Tests and Measurements of headphones
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