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Topic: Low Frequency Effects

	LFE - Wikipedia, the free encyclopedia
		LFE, an abbreviation for Low-Frequency Effects, is commonly used in describing an audio track contained within a motion picture sound mix.
		The LFE channel originated in Dolby Stereo 70 mm Six Track film prints, as a way of providing louder bass and sub-bass effects, without detracting from the quality of the standard audio channels.
		Later formats such as Dolby Digital retained the LFE channel, although this is more through convention and backwards compatibility than necessity, as digital formats have greater dynamic range than the magnetic analogue recordings on 70 mm prints, and modern sound processors have bass management functions to redirect bass from any channel to a subwoofer.
	en.wikipedia.org /wiki/LFE (208 words)

	TVTechnology - Inside Audio
		Low frequencies at high levels require large enclosures with large drivers and lots of power.
		Further, because in reverberant spaces, low frequencies are difficult to localize, it makes sense to have a separate channel and speaker to generate those effects, distinct from the more conventional effects, music and dialogue.
		This is a function of the effects pan from front to rear as the signal grows louder.
	www.tvtechnology.com /features/Inside-Audio/f_dave_moulton.shtml (1189 words)

	Interferential Therapy (Site not responding. Last check: 2007-10-22)
		This is due to the resistance (impedance) of the skin being inversely proportional to the frequency of the stimulation.
		Interferential therapy utilises two of these medium frequency currents, passed through the tissues simultaneously, where they are set up so that their paths cross and in simple terms they interfere with each other.
		The magnitude of the low frequency interference current is approximately equivalent to the sum of the input amplitudes.
	www.electrotherapy.org /electro/interferential/interferential.htm (1222 words)

	Studio Technologies, Inc. -- Model 65 Bass Manager (Site not responding. Last check: 2007-10-22)
		This ensures that the proper relative level is maintained between the LFE signal and the low-frequency energy derived from the main inputs.
		However, when the bass management bypass function is active the LFE signal continues its normal flow to one or both of the subwoofer outputs.
		When remote LFE mute is active, normal bass management operation continues, but the LFE signal is not routed to either of the subwoofer outputs.
	www.studiotechnologies.com /ProductPage-M65.htm (1793 words)

	BUTTKICKER LFE (Site not responding. Last check: 2007-10-22)
		LFE features extended low frequency response for powerful bass response and special effects.
		The ButtKicker LFE (low frequency effects) utilizes a patented magnetic suspension which is different from any other speaker or shaker and can be used couches, theater seating, platforms, and any type of structure.
		It is similar to a loudspeaker, but instead of moving a cone, and transferring sound waves through the air, it attaches to seats and floors, and sends low frequency sound directly into the listener's body.
	www.guitammer.com /LFE_home.html (558 words)

	[No title]
		Generally L.F.E. (low frequency effects) sounds are recorded at a higher level and this setting should function for both.
		LOW PASS FREQUENCY: The low pass frequency control adjusts the point at which the subwoofer becomes active.
		By removing this circuit (setting to off-out-bypass), the low frequency point is controlled by the equipment feeding the signal (receiver, pre-amp or processor).
	www.ugsaudio.com /learn/subsetup.doc (583 words)

	M&K Professional Bass Management page (Site not responding. Last check: 2007-10-22)
		Proper low frequency equalization and mixing decisions are difficult, if not impossible, unless all 5.1 or more channels have the same bass frequency response at the mixers listening position.
		By combining a carefully designed low frequency acoustic rolloff of all the main speakers, including the surrounds, and a matching 2nd order electronic filter in the MandK Bass Management Controller, MandK achieves all the theoretical benefits of a 4th order Linkwitz-Riley filter.
		Full frequency musical content, is assigned or panned around the room via normal console or software operations to the various desired subjective locations such as Left, Center, Right, Left Surround, and so on.
	www.mkprofessional.com /bass_mgmt.htm (786 words)

	NIH Guide: CELLULAR EFFECTS OF LOW FREQUENCY ELECTROMAGNETIC FIELDS
		In this Act, NIEHS is designated as the lead agency for coordinating and conducting the health effects studies and communicating the results to policy makers and the general public on the possible adverse effects, if any, of EMFs by the generation, transport and use of electricity.
		One of the highly cited and studied areas is effects of EMF on the behavior of cells exposed to electric and/or magnetic fields.
		For example, projects that propose to study the effects of 60 Hz EMF on genes should include as an initial study, a replication of the cellular experiments of Henderson and Goodman to establish the laboratory baseline.
	grants.nih.gov /grants/guide/rfa-files/RFA-ES-94-001.html (2611 words)

	Cellular Effects of Low Frequency Electromagnetic Fields - Research Information on the EMFRAPID Program (1994 -1998)
		The epidemiological data on this point is contradictory, and part of the skepticism which surrounds the issue derives from the absence of any well-established mechanism by which EMF could induce oncogenic changes.
		In the case of DNA damage, quite low numbers of strand breaks can cause the cell to stop DNA synthesis until the damage is repaired.
		It is frequently over-expressed in cancer cells, and this contributes to the malignant phenotype.
	www.niehs.nih.gov /emfrapid/extrmurabs/williams.html (1355 words)

	JBL - Car Audio
		Changes to the amplitude vs. frequency characteristic and the phase vs. frequency characteristic of a signal.
		At low frequencies, it can be as little as 4 dB.
		All 5 main channels are full range, so this additional channel, covering the frequency range 3 Hz to 120 Hz is there to accommodate very loud low frequency special effects sounds, such as explosions.
	www.jbl.com /car/technology/glossary.aspx?act=glossary&term=L (903 words)

	High-frequency limitation effects
		The effect of degradation of basic audio quality due to switching off the LFE channel is shown in Fig.
		The obtained results show that excluding of the LFE channel from surround audio reproduction systems may have significant effect on degradation of audio quality, however resultant quality is still "Good".
		Effects of switching off the LFE channel without any filtration of the main channels are also presented in this figure in order to compare the magnitude of the effect for these two types of degradation.
	www.surrey.ac.uk /soundrec/quality/lf.php (698 words)

	Glossary
		The range of frequencies audible to the human ear, generally accepted to be 20 Hz to 20,000 Hz.
		It is used primarily for the transmission of high frequency, such as digital signals or television.
		Just as each speaker can be assigned its own sound information, the LFE channel is meant to be directed to subwoofers (or full-range speakers) as it includes only information in the bass and low-bass range.
	ils.unc.edu /~nguyw/Final/glossary.htm (447 words)

	Low Frequency Effects - LFE
		To the Broadcaster, this means new audio spectrum monitoring equipment, to ensure that the studio's HVAC unit is not providing earth-shaking tremors to audiophiles with equipment capable of reproducing the low frequency rumble coming from his studio's air conditioning system.
		We chose these amps because they have a unique high frequency switching power supply that supplies high current, draws typically 40% of the power of a comparable amp, switches in stages as needed, yet weighs only 21 pounds.
		Transducers are actually bolted to the frame of the couch and other seating, so as to change the low frequency audio signal into an actual vertical motion that can be felt.
	www.tvtower.com /low_frequency_effects.html (323 words)

	Aviation noise and vibration control consulting - Low Frequency Noise
		Residents who live in areas located to the rear and side of aircraft departure runways frequently complain about the low-frequency effects of takeoffs: rumbling noises, rattle of windows, houses “shaking”.
		Detailed measurements made over a one month period near Baltimore-Washington International Airport yielded data that relate measured start of takeoff sound levels to wall vibration levels, to resident ratings of the objectionable nature of the events, and to sound level propagation rates into the community.
		The SEL were found to be too labor intensive to compute; events had to be identified by visual inspection of the sound level time histories since often one takeoff would begin before the sound level from the preceding takeoff dropped sufficiently for automated identification.
	www.hmmh.com /aviation_lowfreq02bwi.html (305 words)

	M&K Professional Bass Mgmt print friendly page 1 (Site not responding. Last check: 2007-10-22)
		These issues include reproducing 5, 7, or more channels of full range audio, plus an optional Low Frequency Effects channel (LFE), all of which have a bandwidth to 10Hz or below, with very high dynamic range, and achieving consistent bass response from all the channels throughout the control room monitoring area.
		When the bass from all the channels is redirected into a single, PROPERLY placed subwoofer, then each and all of the multiple channels exhibits the identical bass response at the listening position, and gives surprisingly even coverage in virtually every control room.
		Simply stated bass management is putting an electronic bass frequency crossover (typically 80 Hz) on all the channels, and redirecting the bass frequencies below 80 Hz from each of the channels to a common subwoofer.
	www.mkprofessional.com /bass_mgmt_pf1.htm (807 words)

	Intel® Desktop Board D845PEBT2 - Audio Sub-System Connectors
		The double stack audio port provides rear channels, low frequency effects, and center channel analog audio outputs.
		The bottom connector is the Low-Frequency Effects (LFE) and center analog audio outputs.
		LFE, or Low-Frequency Effects is what would be connected to a powered sub-woofer.
	support.intel.com /support/motherboards/desktop/D845PEBT2/sb/cs-008837.htm (562 words)

	Bass Management - 1
		To allow the reproduction of powerful sub-bass effects in analog movie soundtracks – asteroids crashing into the Earth and dinosaur footfalls for example – it was necessary to assign such signals their own channel to minimize intermodulation distortion and other unwanted artifacts, and maximize headroom.
		This means that any bass frequency you can imagine can go on any of the “main” channels with no problem, and there is no need to waste a channel on it.
		At the consumer’s home, the LFE is not connected directly to the subwoofer, and it should not be connected that way in the studio.
	www.ambisonic.net /bassmgt1.html (1042 words)

	M&K LFE4 (Site not responding. Last check: 2007-10-22)
		These problems can be addressed by redirecting the bass content from all channels to a single subwoofer source (made up of one or more subwoofers).
		Reducing the sources of low frequency content in a room will reduce room modal interference and increase the constancy and quality of bass throughout the monitoring area.
		The LFE-4 can also be used in a stereo mix environment to feed a summed low frequency signal to one or more subwoofers, addressing a majority of the audio and video industries where mixing for stereo is still the preferred practice.
	www.avantonline.com /mk_lfe4.htm (719 words)

	Dolby \| Glossary
		The LFE, or low-frequency effects, channel on Dolby Digital 5.1-channel soundtracks carries the powerful low bass frequencies (explosions, rumbles, etc.) that are felt more than heard.
		Low frequency effects channel, dedicated to frequencies from 3 to 120 Hz (the ".1" channel, so designated because it corresponds to about 1/10 the full audible range).
		The blend of dialogue, music, and effects which comprises a film's soundtrack.
	www.dolby.com /resources/glossary/index3.html (313 words)

	Half Space
		Most of high frequency signals were attenuated with strong attenuation (small Q values).
		In frequency domain, this displacement is linearly proportional to frequency (more accurately iω).
		But, because the power spectrum is proportional to frequency in nature, the stronger low frequency effects from strong attenuation (small Q) is less observable.
	geoweb.tamu.edu /seung/prbrHalfSpace.htm (284 words)

	Effects of Low Frequency Sound (LFS) (Site not responding. Last check: 2007-10-22)
		The manifestation of vestibular effects from water-borne Low Frequency Sound (LFS) has a potential impact on diver performance and safety, as symptoms may impact mission effectiveness of dive and post dive duties.
		The purpose of this study is to examine the effects of LFS on vestibular processes and to determine the vestibular effects of LFS on humans.
		The project is a multi-year, multi-institution study to establish basic effects of auditory stimulation of the vestibular system and characterize acute and cumulative effects on vestibular function of LFS in humans.
	www.namrl.navy.mil /clinical/projects/lfaplan1.htm (563 words)

	Extremely Low Frequency Effects On Humans (Site not responding. Last check: 2007-10-22)
		effects on humans mentions drug or alcohol simulation capabilities.
		that the frequency effect internal to the brain, is the difference
		effects of 8 Hz are the meditation or ESP states in humans.
	www.unexplainable.net /artman/publish/printer_1759.shtml (249 words)

	5dot1.com - Bass Management (Site not responding. Last check: 2007-10-22)
		The LFE channel is used for adding Low Frequency Effects that consist of sounds in the 20Hz to 120Hz range or Dinosaur footsteps thumps.
		Both of these low frequency audio channels are then added together and sent to your subwoofer.
		It is meant to extend the low frequency range down to 20 Hz or even lower.
	www.5dot1.com /articles/bass_management.html (691 words)

	LFE (Low Frequency Effects) (Site not responding. Last check: 2007-10-22)
		Audio channel found in 5.1 digital surround sound audio schemes (the.1) that carries only low frequency information of 80 Hz and below.
		The LFE channel drives a subwoofer to provide extremely low bass extension.
		Systems not using subwoofers can shunt the LFE information to the main speakers in the surround sound set-up.
	www.orionstudios.com /help/lfe.html (52 words)

	Sound And Vision Magazine - Resource Center: Surround Sound
		All A/V receivers and surround processors provide bass management, which is a system for routing low frequencies to speakers according to their ability to handle deep bass.
		There you indicate whether or not the system includes a subwoofer and whether each speaker is “large” or “small.” If the system has a subwoofer, it receives the signal from the LFE (low-frequency effects) channel in 5.1-channel soundtracks and the low bass from all channels connected to speakers designated as small.
		If the system does not have a subwoofer, the LFE and bass from channels designated as small are distributed evenly to the speakers designated as large.
	www.soundandvisionmag.com /article.asp?section_id=10&article_id=856&page_number=5 (564 words)

	Top Review Shop - Buttkicker LFE Kit Review
		The Buttkicker LFE is a tactile transducer - meaning that it produces vibrations that actually shake the furniture to which it is attached.
		The Buttkicker LFE kit contains the BKA1000-4 amplifier, ButtKicker LFE unit, mounting plate, 14AWG speaker wire, line-level speaker adaptor, "Y" splitter interconnect, single RCA interconnect, mounting screws and bolts, a set of rubber isolators and installation instructions.
		The Buttkicker LFE unit has a frequency response of 5 - 200 Hz, with power handling of 400 watts min.
	www.topreviewshop.com /Buttkicker_LFE.html (298 words)

	Ultimate AV: Earthquake SuperNova MKIV-15
		The Iron Law states that the efficiency of a woofer system is directly proportional to its cabinet volume and the cube of its cutoff frequency (the lowest frequency it can usefully reproduce).
		A passive radiator is essentially a speaker without a drive mechanism (no magnet or voice-coil) that moves in sympathy with the vibrations and pressure created by the active speaker.
		Group delay (in which some frequencies reach your ears before others) and phase-shift effects are moved to much lower frequencies, where their negative effects become inaudible.
	www.guidetohometheater.com /speakersystems/60/index.html (1107 words)

	JBL PB-12II Powered Subwoofer
		The 12-inch pure cellulose fiber cone reproduces low frequencies with extreme accuracy and minimal distortion, just like the woofers JBL uses at rock concerts, arenas and in movie theaters around the country.
		The LFE input bypasses the subwoofer's internal, user-adjustable low-pass crossover network, to avoid unnecessary reprocessing of the low-frequency effects channel of the digital soundtrack.
		The result will rock the room with floor-shaking effects like explosions, earthquakes or even the rumbling of the engines in an airplane.
	www.acousticsounddesign.com /core/view_BigProduct.cfm?PID=406 (120 words)

	Adcom - GDD-1 CD Dolby Digital Processor (Site not responding. Last check: 2007-10-22)
		And, of course, traditional Adcom amplifier stages using proprietary solid state devices, Class "A" biased, are basic in the GDD-1 audio circuitry.
		When using a subwoofer for the low frequency effects, the GDD-1 offers full digital bass management.
		This significantly improves phase coherence, frequency and transient response in the low frequency range.
	www.adcom.com /cddigital/gdd1.htm (358 words)

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