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Topic: Sound impedance

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Sound intensity

Sound pressure level

Speed of sound

Sound power

Sound power level

Threshold of pain

Impedance

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	Acoustic impedance - Wikipedia, the free encyclopedia
		The acoustic impedance Z (or sound impedance) is the ratio of sound pressure p to particle velocity v in a medium or acoustic component.
		The characteristic impedance of a medium (usually air, but also for instance exhaust gases in a muffler) is the ratio of sound pressure p to particle velocity v in open field (i.e.
		The acoustic impedance Z of an acoustic component (in Pa·s/m) is the ratio of sound pressure p to particle velocity v at a transition with a previous component:
	en.wikipedia.org /wiki/Sound_impedance (265 words)

	Sound - Open Encyclopedia (Site not responding. Last check: 2007-10-09)
		Sound is a mechanical compression and rarefaction or a longitudinal displacement wave that propagates through a medium (solid, liquid or gas).
		Sounds that are sine waves with fixed frequency and amplitude are perceived as pure tones.
		While sound waves are usually visualised as sine waves, sound waves can have arbitrary shapes and frequency content, limited only by the apparatus that generates them and the medium through which they travel.
	open-encyclopedia.com /Sound (566 words)

	Sound - Biocrawler definition:Sound - Biocrawler (Site not responding. Last check: 2007-10-09)
		In sound waves parts of matter (molecules or groups of molecules) move in a direction of the spreading of the disturbance (as opposite to transversal waves).
		A sound wave is usually represented graphically by a wavy, horizontal line; the upper part of the wave (the crest) indicates a compression and the lower part (the trough) indicates a rarefaction.
		The characteristics of sound are frequency, wavelength, amplitude and velocity.
	www.biocrawler.com /biowiki/Sound (970 words)

	tip_25
		Adding the loudspeaker impedance to the model, it is easy to show that since the cable impedance is in series with that of the loudspeaker, a speaker cable can actually modify the loudspeaker's frequency response.
		All of these effects clearly impact the sound, but because their precise nature is unpredictable and usually deleterious, I would therefore be the last guy on this planet to recommend high-impedance speaker cable.
		Its sound is a tad less liquid and textures are a bit brighter relative to 8N copper.
	www.blackdahlia.com /tipindex/tip_25/tip_25.html (8715 words)

	The Enigma of Sound Power Measurements at Low Frequencies (Site not responding. Last check: 2007-10-09)
		The sound pressure was measured for 4 different sound source positions on the floor and for each position and each third octave band the levels were integrated linearly for two microphone rotation period of 64 seconds by the Type 4426.
		The sound pressure level was measured with a moving microphone in the middle of the room while a second microphone was placed 3 cm from one wall, 3 cm from two walls, i.e.
		As a result the total sound pressure level measured, and hence the sound power evaluated, would be too low as compared to the case of the free-field where the contribution from the individual frequencies emitted by the source to the total sound pressure is independent of the room (where there are no resonances).
	www.zainea.com /enigma.htm (6458 words)

	How the Impedance Spectra were Obtained
		It is also worth noting that the sound spectrum is only one of the things that determine the timbre of the note, so that one cannot easily get an idea of the sound of the note from just the spectrum (particularly one also needs to know the starting transient and the vibrato).
		For serious study, the effects of impedance spectra on the spectra of the sound produced, the comparison should be made on similar flutes.
		The speed of sound, and therefore the frequency of the notes produced by the flute, increases with temperature and humidity.
	www.phys.unsw.edu.au /music/how.html (1208 words)

	Impedance, and how it affects audio equipment
		Negative impedance is exactly what it sounds like - the amplifier is modified so that the voltage output rises with increasing load.
		Then there are impedance dips, where the actual impedance may fall to 1/2 (or less) the rated impedance.
		Generally, it is desirable that the output impedance is low, and the destination impedance high, and this is the case with the majority of modern equipment.
	sound.westhost.com /impedanc.htm (5822 words)

	ipedia.com: Sound pressure Article (Site not responding. Last check: 2007-10-09)
		Sound pressure p is the measurement in pascals of the average sound wave pressure variations as the sound wave passes by a fixed point.
		Sound pressure p (acoustic pressure) is the measurement in pascals of the average sound wave pressure variations as the sound wave passes by a fixed point.
		The amplitude of sound pressure decreases in the free field (direct field) with 1/r of the distance of a point source.
	www.ipedia.com /sound_pressure.html (264 words)

	Klaus Wogram: The strings and the soundboard
		For this reason, experiments were made to determine the general influence of ribs on input impedance and sound radiation.
		Turning to the sound radiation, the same effects were observed as for the impedance; the lower resonant frequencies are shifted downwards and sound radiation is reduced.
		Every second rib was removed by routing it down to the level of the soundboard, and input impedance and sound radiation were measured.
	www.speech.kth.se /music/5_lectures/wogram/ribbing.html (937 words)

	CHANDLER LIMITED TG2 Pre Amp with PSU
		The sound was used on many famous recordings done at Abbey Road including The Beatles "Abbey Road" and Pink Floyd's "Dark Side of the Moon" and its amplifiers used in many EMI circuits of the time.
		The Impedance switching option allows for input impedance of each channel to be switched between the 300Ω and 1200Ω values.
		The signal is mixed from both pre amps and is sent to the output of the second channel with that channels pot acting as a master fader.
	www.mercenary.com /chtg2preamp.html (998 words)

	Acoustic impedance -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-09)
		Also it is the product of the density of air ρ (rho) and the (Click link for more info and facts about speed of sound) speed of sound c.
		The acoustic impedance Z in Pa·s/m (or, in the equivalent units common before the pascal was added to (A tetravalent nonmetallic element; next to oxygen it is the most abundant element in the earth's crust; occurs in clay and feldspar and granite and quartz and sand; used as a semiconductor in transistors) SI, N·s/m
		The acoustic impedance (characteristic impedance) of air is Z = 410 Pa·s/m at the (The degree of hotness or coldness of a body or environment (corresponding to its molecular activity)) temperature 25 °C (77 °F) or 413 Pa·s/m at 20 °C (68 °F).
	www.absoluteastronomy.com /encyclopedia/a/ac/acoustic_impedance.htm (341 words)

	The educational encyclopedia, acoustics (Site not responding. Last check: 2007-10-09)
		Frequency spectrum of a sound a sound which consists of a single frequency is called a pure tone, musical sounds contain a fundamental frequency plus several harmonics
		Loudness loudness is a subjective term describing the strength of the ear's perception of a sound.
		Sound spectrum sound spectrum is a representation of a sound - usually a short sample of a sound - in terms of the amount of vibration at each individual frequency.
	users.telenet.be /educypedia/electronics/acoustictopics.htm (637 words)

	SoundStage! Getting Technical Back-Issue Article (5/2004)
		Traditional tube sound can be described as warm, with fuller-sounding bass, and a sense of space even when music reaches high levels.
		What Hamm discovered was that, when distorted, both tubes and transistors sounded distorted and when in their normal, non-overload range they both sounded very clean.
		Let’s say that a tube amplifier with transformer has an output impedance of 4 (using 4-ohm output taps), and let’s say that the speaker impedance range is between 6 and 3.
	www.soundstage.com /gettingtechnical/gettingtechnical200405.htm (1508 words)

	Driving Audio Piezoelectric Transducers - Maxim/Dallas
		The relationship between source impedance and sound pressure level is measured, single-ended (S/E) and bridge-tied load (BTL) driving schemes are compared and the input impedance of a PZT is characterized.
		The source impedance for this test was 253.5 ohms with a 0V to 5V square wave driving the PZT at its peak sound pressure output frequency of 5.6kHz.
		Curves of source impedance versus sound pressure amplitude at peak sound pressure producing frequency were developed for all three PZTs tested as a guide to designing higher source impedance drivers to minimize peak power supply and driver currents and yet maintain an acceptable reduction in sound pressure amplitude.
	www.maxim-ic.com /appnotes.cfm/appnote_number/988 (1840 words)

	Sound Pressure (Site not responding. Last check: 2007-10-09)
		The amplitude of sound pressure from a point source decreases in the free field (direct field) proportional to the inverse of the distance r from that source.
		Sound pressure level is a decibel scale based on a reference sound pressure of 20 ÂµPa (micropascals), calculated in dB as: :
		"Sound intensity" is sound power per unit area, while "pressure" is a measure of force per unit area.
	restrictedsection.com /sound-pressure.html (434 words)

	Speed of Sound and Air Conditions (Site not responding. Last check: 2007-10-09)
		You are asking about the attenuation of sound, not its speed, which is a factor but not the only one.
		The speed of sound in dry air at 0 degrees C is about 330 meters per second, nearly 1,200 kilometers per hour.
		In water, sound travels about four times as fast as it does in air, while in steel, the speed of sound is about fifteen times as great as in air." You might be able to find this textbook in your local library.
	www.newton.dep.anl.gov /askasci/phy00/phy00591.htm (397 words)

	diyAudio Forums - High impedance out amps VS as low as possible.
		The two major reasons to have a low output impedance is to improve damping of the woofer and to make sure that the electrical response at the speaker terminals is flat over the frequency band.
		The magnitude of the reflected signal is directly related to the impedance of the line and the impedance at the end of the cable that it reaches.
		The output impedance was very high at around 1 ohm and it sounded far inferior to the Audiolab 8000 amp with an output impedance of much less than 0.1 ohm.
	www.diyaudio.com /forums/showthread.php?postid=74533 (1627 words)

	FAQ: rec.audio.* Amplifiers 1/98 (part 4 of 13) (Site not responding. Last check: 2007-10-09)
		The sound from that "new speaker" will not be as precisely localized as it would from one speaker, so your stereo image may be hurt.
		To start with, sound pressure, measured in dB, often stated as dB SPL, is a function of the log of the acoustic "sound" power.
		All three, Mark V, Old Colony, and Sound Values kits have been built by satisfied rec.audio.* posters, although quality of the Mark V kit is lower than the others.
	omicron.felk.cvut.cz /FAQ/articles/a3136.html (7555 words)

	GOLD AND DIAMONDS, (Site not responding. Last check: 2007-10-09)
		They have almost the same acoustic impedance, a fact which two physicists are hoping to exploit in order to get nanoparticles, embedded in a crystalline network, to ring with a pure tone, which in turn should help in the development of various nanotechnology devices.
		The acoustic impedance, the acoustic analogue of a material's optical index of refraction, is defined as the density times the velocity of sound in that material.
		Thus, these two materials are very different in many respects but alike in their impedance to sound, which is to say their propensity to take up or dissipate sound energy.
	newton.ex.ac.uk /aip/glimpse.txt/physnews.695.1.html (425 words)

	The PC Guide Discussion Forums - low sound
		I have sound in windows and cd-rom, but I have to put my ear to the speaker to hear its that low.I also have a multifunction adapters in my device mgr.with the same drivers as the sound,video and game controllers.
		Impedance matching is important to quality of sound and sometimes volume level too.
		The source (mic) must be lower than the equipment's (amplifier's) impedance or the resistance to flow will be too great and signal to noise will become a factor because you will have to amplify it even more to be at audible levels.
	www.pcguide.com /vb/showthread.php?t=25905 (2193 words)

	Head-Fi (Headphone Hi-Fi and Portable Audio) - What is the ASL UHC Signature?
		It doesn't seem to add or change the sound of the amp you use it with.
		It can sound as good or better than some dedicated headphone amps, but I've also heard the combination bested by one or two dedicated headphone amps.
		As far as robust sounding power, it depends on the amplifier you hook up to it.
	www.head-fi.org /forums/printthread.php?t=46265 (819 words)

	Sound pressure level, particle velocity, acoustic impedance, sound intensity characteristic impedance dB SPL ... (Site not responding. Last check: 2007-10-09)
		Sound pressure level, particle velocity, acoustic impedance, sound intensity characteristic impedance dB SPL calculations ohm's law of the acoustics pascal audio calculations - sengpielaudio
		Sound pressure, particle velocity and acoustical impedance belong to the linear sound field values.
		The sound intensity is a quadratic sound energy value.
	www.sengpielaudio.com /calculator-ak-ohm.htm (215 words)

	RMRC • Research • Research Project 5
		The basic hypothesis of this research is that inclusions with porous and/or flexible characteristics will act as tiny 'sponges', absorbing sound energy in the pavement.
		To expedite the testing, Dr. Gress and his graduate student Jonathan Pitre constructed a simple and inexpensive sound impedance tube that allows them to quickly screen potential concrete mixtures for desirable sound absorbing capabilities.
		It was found that a standard concrete mix made with local 4.75 mm mineral aggregate and 10 percent paste had an optimum thickness of 7 inches.
	www.rmrc.unh.edu /Research/Rprojects/Project5/p5abstract.asp (388 words)

	West Mountain Radio - RIGblaster Specifications
		The three sound card audio signals are isolated using three audio transformers.
		A high grade DC blocking capacitor is on the sound card to mic.
		The sound card audio is isolated from ground using an audio transformer.
	www.westmountainradio.com /specs.htm (543 words)

	Speed of sound in air and the temperature calculator. No air pressure table density of air calculation acoustic ... (Site not responding. Last check: 2007-10-09)
		The speed of sound c depends on the temperature of air and not on the air pressure!
		rho is the density ρ and p is the sound pressure.
		of sound is alike on a mountain top as well as at sea level with equivalent air temperature.
	www.sengpielaudio.com /calculator-speedsound.htm (348 words)

	SpeakerBuilding.com - Making of M2, Page 4 (Site not responding. Last check: 2007-10-09)
		Impedance and sound pressure level of each units are necessary and It's already measured in step 4.
		Impedance result of M2 show the final test result of M2.
		Instead, It's sound seems to be quite dependent on the sound absorbing material.
	www.speakerbuilding.com /content/1022/page_4.php (398 words)

	Physics News 695, August 5, 2004
		In the TASHE system, intense, spontaneously generated sound waves (in the place of mechanical pistons in the 19th-century design) shuttle parcels of helium gas between a cold end and hot end.
		Thermally driven expansion and contraction of the gas, in concert with pressure oscillations (induced by the temperature difference), intensify the power of the initial sound waves which become strong enough to drive a piston connected to the device.
		The motion of the piston vibrates a coil of copper wire that produces electricity as it moves relative to a permanent magnet.
	newton.ex.ac.uk /aip/physnews.695.html (954 words)

	AcoPacific - Simple Intensity TM
		The SI7KIT is a complete microphone system including: SI7 probe holder; choice of 1/2 Inch Phased Matched Pairs; 2- 4012 preamps and cables; PS9200 Power Supply; AC adaptor; and the SC1 fitted storage case.
		Sound In tensity (Acoustical Intensity) permits accurate source location and measurement of sound sources in highly reverberant environments.
		Applications include measurement of: fan noise, speaker cabinet sound radiation, heavy equipment noise; and profiling a horn drivers.
	acopacific.com /simplein.html (429 words)

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