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Topic: Audio system measurements

Related Topics

Noise level

SNR

Distortion

Total harmonic distortion

List of noise topics

Audiophile

THD

Acoustic power

Loudspeaker acoustics

White noise

Sound reproduction

Shot noise

Sound recording

Frequency

Amplifier

	Audio system measurements - Wikipedia, the free encyclopedia
		The designer of a system for sound reproduction needs to be able to measure the system's performance in a number of areas.
		In balanced audio systems, equal and opposite signals (difference-mode) are used, which are subtracted, canceling out interference which affects both signals equally (common-mode).
		The measure of the low frequency noise contributed by the turntable of an analogue playback system.
	en.wikipedia.org /wiki/Audio_system_measurements (1489 words)

	Total harmonic distortion - Wikipedia, the free encyclopedia
		The total harmonic distortion, or THD, of a signal is a measurement of the harmonic distortion present, that is, any departure of the output signal waveform from that which should result from the input signal waveforms being operated on by the system's specified or ideal transfer function.
		This is a measurement of the extent of that distortion.
		Measurements for calculating the THD are made at the output of a device under specified conditions.
	en.wikipedia.org /wiki/THD (279 words)

	Audio system measurements -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-09)
		The designer of a system for (The reproduction of sound) sound reproduction needs to be able to measure the system's performance in a number of areas.
		This is measured in samples per second, or (The unit of frequency; one Hertz has a periodic interval of one second) hertz.
		Since independent digital audio devices are each run by their own (An oscillator that produces electrical oscillations at a frequency determined by the physical characteristics of a piezoelectric quartz crystal) crystal oscillator, and no two crystals are exactly the same, the sample rate will be slightly different.
	www.absoluteastronomy.com /encyclopedia/a/au/audio_system_measurements.htm (1658 words)

	Audio Measurements Made Easy with LabVIEW - Tutorial - Development Library - National Instruments
		Audio measurements, one of the most demanding tasks, require high-quality signal acquisition, complex scaling, extensive analysis, and multiple graphical presentations.
		The measurement is usually presented as the ration of the undriven channel to the driven channel in decibels.
		A common specification for audio systems is the dynamic range –; the ratio of a full-scale signal to the smallest signal in the system.
	zone.ni.com /devzone/conceptd.nsf/webmain/CE46CCEDEBE745FA86256CC3007F9C06?opendocument (2553 words)

	FREQUENCY RESPONSE ALTERNATE GENIE SEARCH ENGINE, INC
		The frequency response is typically characterized by the ''magnitude'' of the system's response, measured in dB, versus frequency.
		Once a frequency response has been measured (e.g., as an impulse response), providing the system is linear and time-invariant, its characteristic can be approximated with arbitrary accuracy by a digital_filter.
		Similarly, if a system is demonstrated to have a poor frequency response, a digital or analog_filter can be applied to the signals prior to their reproduction to compensate for these deficiencies.
	www.agseinc.com /frequency_response (243 words)

	Tektronix MBD: Applications > Digital TV Systems - Monitoring and Measurements
		In addition to the traditional television system measurements there's a new dimension for test and measurement to quantify the various parameters associated directly with the serial waveform.
		Program signal measurements are essentially the baseband video and audio measurements that have been used for years.
		An important aspect to these measurements is that the accuracy of signal representation is limited by the number of bits-per-sample.
	www.tek.com /Measurement/App_Notes/DigitalTV/monitor.html (550 words)

	DYNAMIC RANGE FACTS AND INFORMATION (Site not responding. Last check: 2007-10-09)
		In digital audio, the maximum possible dynamic range is given by the bit_resolution.
		In digital systems or devices, the ratio of maximum and minimum signal levels required to maintain a specified bit_error_ratio.
		In audio and electronics applications, the ratio involved is often so huge that it is converted to a logarithm and specified in decibels.
	www.whereintheworldisbush.com /dynamic_range (281 words)

	SUB_INDEX_graphs
		Jump directly ahead to the audio system acoustic measurements section of this html document.
		These measurements (without comment for the time being), were made just two days ago (26th May 04) after I re-worked the midrange and horn EQ to make the system more balanced:
		These are graphs of the first measurements that I made after moving to my new town house, and setting up the audio system for the first time.
	jgbouska.tripod.com /audio/sub_index_graphs.htm (3404 words)

	Audio System Upgrades
		Initial impressions of stock system was that it was a little bass heavier than the upgrade system with the "premium" speakers.
		Upgrade to premium system at the dealer consisted of cd player (single in dash, no cassette, or cassette with cd controller and 6 disc in dash changer) and a 6 speaker system - tweets and mids in doors, and 6" midbasses in rear.
		So after taking a couple measurements to make sure the new tweets would be screwed to the metal behind the grill of the tweeter molded in the door panel, I marked the spot to drill the screw in and fired away.
	www.geocities.com /treading_lightly/audio.html (1399 words)

	DIY Network: HOME IMPROVEMENT
		The way that you use the room in which your audio system will be installed may have an impact on your purchase decisions.
		Surround-audio systems give the listener a three-dimensional sound experience and are commonly used in conjunction with a home-theater system.
		Finally, if your system is to be for family use, look for equipment that is simple enough for all family members to learn how to operate.
	www.diynet.com /diy/cda/article_print/1,1983,DIY_13954_2273226_ARTICLE-DETAIL-PRINT,00.html (1156 words)

	Visteon Corporation: Audio Systems Testing
		Although our audio engineers work towards the ultimate goal of constantly improving listeners' subjective responses, the majority of our testing is based on objective criteria.
		Using a six-microphone measurement array, Visteon engineers measure the effects of different interior materials, components and road noise on audio system quality to understand how interior space affects listener satisfaction with audio system performance.
		With precise recordings that recreate audio system performance, including the imaging and ambience, listeners rate quality on a scale of 1 to 5, without knowing the type of vehicle or system being tested.
	www.visteon.com /products/capabilities/audiosys_testing.shtml (540 words)

	ExtremeTech: E-MU 0404 Digital Audio System (Site not responding. Last check: 2007-10-09)
		They usually won't accelerate game audio, and their mixer applications are much more intricate and granular.
		Cubase LE: The newer entry-level audio sequencer application from Steinberg, this is the OEM bundle version that's similar to Cubase SE.
		The numbers at 96KHz/24-bit and 192KHz/24-bit are equally impressive, and the 0404 is one of the cleaner audio interfaces we've measured.
	www.findarticles.com /p/articles/mi_zdext/is_200501/ai_n8963649 (1377 words)

	W4NEQ audio terms and measurements
		Recently there seems to be some interest in certain quarters about applying broadcast style audio treatments to ssb (and AM) transmission for communications, in the hope of achieving really "good audio", which although itself a subjective moving target, can in fact be quantified to a large degree.
		The frequency response of an audio system is perhaps what is most noticed by people when judging quality.
		The signal-to-noise ratio is the same measurement between the operating level and the noise floor.
	www.scott-inc.com /ham/aud_qual.htm (1616 words)

	High fidelity - Art History Online Reference and Guide
		Meanwhile, the rise of radio was popularizing the use of sound reproduction by means of tube amplifiers and loudspeakers, so you had the curious anomaly of a period of time during which radio receivers commonly used loudspeakers and electronic amplifiers to produce sound, while phonographs were still commonly purely mechanical and acoustic.
		A very popular type of system for reproducing music from the 1970s onwards is the integrated music centre, a natural successor to the older stereogram or radiogram.
		However, the D-B audio listening test was first described by Dan Shanefield, in November of 1974, in the newsletter of the Boston Audio Society.
	www.arthistoryclub.com /art_history/HIFI (980 words)

	Speaker Enclosure Volume Calculator
		If you want a system to produce a lot of SPL (but have limited power or number of speakers), you'll probably have to concentrate a lot of the acoustic energy within a small band of frequencies.
		You could design a system that would produce the desired SPL at all frequencies but it would require significantly more power and speakers than the aforementioned system with the narrow peak.
		To build a system that had a perfectly flat frequency response (generally desired by audiophiles), you'll have to take the vehicle's transfer function into account (this will be discussed later).
	www.bcae1.com /spboxnew2.htm (4086 words)

	Oricom PTB Scope Display (Site not responding. Last check: 2007-10-09)
		In this case, the signal was produced by the PTB's internal sinewave generator, and applied to an amplified audio speaker system.
		The amplifier output was measured with the bass boost alternately enabled and disabled.
		In-depth information about using the Pocket TestBench for audio system measurements is given in AppNote AN-PTB02 - Audio System Testing Using the PTB - see Download section of the Testbench page.
	www.oricomtech.com /sub2/ptb-sco.htm (266 words)

	Review: E-MU 0404 Digital Audio System (Site not responding. Last check: 2007-10-09)
		This isn’t unusual among professional audio interfaces and shouldn’t be a problem for most users, as most modern media players support the real-time ripping and streaming of CD audio.
		The breakout cable design is not uncommon among audio interfaces. This design makes it possible to provide extended connectivity on a single PCI card despite the limitations imposed by the size of the card's back plate.
		This upgrade will be free to all Digital Audio System and Emulator X owners and will enable the use of the E-MU's hardware accelerated effects as VST plug-ins.
	www.kordak.net /0404/review.htm (1444 words)

	Avotec - Silent Scan
		Successful audio stimulation for fMRI is a tough task because of the high ambient noise levels from the gradients.
		audio system consist of the electrical input to the transducer, the transducer output, the coupling of the transducer output to the headset via the tubing assembly, and the coupling of the tubing acoustic output to the patient's ears.
		We measure the sound pressure output of the tubing assembly by using a 2cc coupler to connect the tubing assembly to the measurement microphone.
	www.avotec.org /silentscan.htm (1364 words)

	Articles - High fidelity (Site not responding. Last check: 2007-10-09)
		A very popular type of system for reproducing music from the 1970s onwards is the integrated music centre--the successor to the older stereogram or radiogram.
		The double-blind audio listening test, however, was first described by Dan Shanefield in November of 1974 in the newsletter of the Boston Audio Society.
		It was, for example, discovered that a realistic representation of the separation between performers in an orchestra from an ideal listening position in the concert hall would require at least three loudspeakers for the front channels.
	www.digital-voicerecorders.net /articles/High_fidelity (1550 words)

	pcRTA - True RMS 1/3 Octave Real Time Analyzer
		The complete system consists of an ISA full length PC slot card, a connector interface box, the Windows based operating software, and can utilize up to four calibrated M51, M52 or M53 microphones.
		The system features a 4 microphone multiplexer which enables true spatial averaged measurements to be performed directly by the analyzer - a growing requirement in today’s complex audio fields.
		The pcRTA is very well suited to precision car audio system measurement, and also provides built in scoring routines for competition systems.
	www.linearx.com /products/analyzers/pcRTA/pcRTA_01.htm (338 words)

	wikien.info: Main_Page (Site not responding. Last check: 2007-10-09)
		Frequency response is the measure of any system's response to frequency, but is usually used in connection with electronic amplifiers and similar systems, particularly in relation to audio signals.
		For example, a high fidelity amplifier may be said to have a frequency response of 20Hz - 20,000Hz ±1dB, which tells you that the system responds equally to all frequencies within that range and within the limits quoted.
		As such it is not a measure that is very useful in terms of the quality of reproduction, only that it fulfils the basic requirements needed for it.
	www.hostingciamca.com /index.php?title=Frequency_response (141 words)

	Visteon Corporation: Audio Systems Testing (Site not responding. Last check: 2007-10-09)
		While Visteon audio engineers work toward the ultimate goal of constantly improving the subjective responses of listeners, the majority of testing efforts are based on objective criteria.
		Focusing upon scientific measurements and documentation, these engineers can deliver the best quality to a wide range of audio systems and vehicle types.
		With precise recordings that recreate audio system performance, including the imaging and ambience, listeners rate sound quality on a scale of 1 to 5, without knowing the type of vehicle or system being tested.
	www.visteon.com /about/features/2002/050102.shtml (555 words)

	Sound System Measurements (Site not responding. Last check: 2007-10-09)
		TDS, or Time Delay Spectrometry, is a technique that can be used to measure the system response of electro-acoustical systems (such as a loudspeakers) in "real-world" reverberant environments.
		The technique can also be expanded to measure the system response of an acoustic environment such as an auditorium or concert hall.
		After searching for a unified source of information on electro-acoustical measuring techniques, we found few sources of information that gave us a broad overview about the mechanisms and practical applications of the various techniques that we have tried to present.
	www.owlnet.rice.edu /~elec301/Projects00/elec301 (288 words)

	SoundStage! - Wilson Audio Specialties Factory Tour (11/2001)
		Wilson Audio has found that no one material is ideal for all uses, so a major part of the design process is determining which material to use for each element of a speaker.
		Wilson Audio's visual standards are higher than those in the automotive industry, and the rationale for this made sense to me: cars move and speakers don't, so it's much easier to see any imperfections on speakers.
		A demonstration of the new Sophia preceded listening to Wilson Audio's flagship, the $225,000 dynamic/electrostatic WAMM system, 53 of which are in existence.
	www.soundstagelive.com /factorytours/wilson (2297 words)

	The Mazda NB OEM Audio System FAQ
		One of the many changes was the audio options: Every aspect of the sound system is different from the earlier cars, with the most notable differences being the loss of headrest speakers and the addition of an optional Bose "upgraded" system for the car.
		There are a number of different sound systems to be found in NB cars, each available in "Bose" and "Non-Bose" variants.
		Even though the later Bose systems aren't supposed to be affected by the infamous Bose Buzz that affected the '99 cars, many people (including myself) do hear a distinct buzz from the door speakers in wet weather.
	www.miata.net /garage/nbaudio (5677 words)

	Buzz Audio Professional Products and Services
		Buzz Audio is a 100% New Zealand owned and operated company with a passion for anything to do with sound.
		The EX29 Extreme Isolation Headphones were invented by a US studio session drummer for Drummers, Home Studios, Stage and Studio musicians, and anyone who wants serious isolation of outside sound, read more...
		In April 2000 a 30+ mic preamp shoot-out was conducted by Lynn Fuston of 3D Audio in Nashville.
	www.buzzaudio.co.nz (166 words)

	E-MU 1820 Digital Audio System
		The Digital Audio Systems family consists of three models: 1212M, 1820, and 1820M, the figures standing for the numbers of inputs/outputs.
		There is the opinion that self-made measurements are absolutely useless and that professional equipment is necessary for tests.
		Most system crashes are caused by a single application running into a bug or out of resources.
	www.digit-life.com /articles2/creative-emu-1820 (1760 words)

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