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Topic: Low frequency


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  Low Frequency Noise Conference 2006 Home Page
The 12th International Conference on Low Frequency Noise and Vibration and its Control was held in Bristol, UK from the 18th to 20th September 2006.
Engineers, Scientists and Practitioners concerned with low frequency noise and vibration in industry and the environment and those who wish to extend their knowledge of these areas.
The conference covers all topics in low frequency noise and vibration, its effects and control.
dialspace.dial.pipex.com /prod/dialspace/town/pipexdsl/s/ascc85/lf2006   (1000 words)

  
  Low Frequency Residual Hearing Revisited
Even though residual low frequency hearing may be insufficient to comprehend speech through audition alone, this does not mean that it cannot foster speech perception.
In a sense, the provision of low frequency residual hearing for environmental sound awareness is precisely parallel to the situation that existed when the first generation of cochlear implants were introduced.
Lowering the frequency range of hearing aids fit on children with just low frequency residual hearing can increase their perception of these signals, thus fostering their awareness of the prosodic and melodic dimensions in human voices.
www.hearingresearch.org /Dr.Ross/low_frequency_residual_hearing_r.htm   (3338 words)

  
 purevolume™ | low frequency, pilot
low frequency, pilot hasn't posted a blog yet.
low frequency, pilot hasn't posted any shows yet.
All songs, lyrics and pictures © low frequency, pilot.
www.purevolume.com /lowfrequencypilot   (48 words)

  
 Low Frequency Machinery Monitoring
Low frequency readings are generally expressed in terms of velocity (inches per second), or displacement (mils peak to peak).
Low frequency accelerometers are susceptible to high frequency overload and may contain low pass filters to attenuate high frequency signals.
The low frequency noise of an accelerometer is proportional to the gain (amplification) of the circuit and inversely proportional to the charge sensitivity of the piezoelectric sensing element
www.wilcoxon.com /technotes/lowfreq.html   (5451 words)

  
 Low Frequency 2002 Conference Homepage revision 25 March 2002
Following on from the highly successful 9th Meeting in Aalborg, Denmark, the 10th Meeting in York was bring together international experts and others in the field of low frequency noise and vibration.
The conference covers all topics in low frequency noise and vibration, its effects and control.
Perception of low frequency noise and vibration by man and animals: effects on man and animals
homepages.tesco.net /~lyn.leventhall/lf2002   (373 words)

  
 Very Low Frequency TMD
These advantages came to the fore when CSA Engineering was asked to design a very low frequency tuned mass damper for a large solar array that would power a spacecraft in orbit.
At these very low frequencies, stiffness forces in the TMD must be very small and even slight friction can "lock up" the device and prevent it from damping.
Because the very low frequency causes elastic (spring) forces to be small compared to weight forces, a special means was required in the ground versions for offloading the weight of the moving mass.
www.csaengineering.com /actsys/lowfrequencydampers.shtml   (763 words)

  
 THE LOW FREQUENCY IN STEREO
Low Frequency In Stereo will be performing at Bylarm in Oslo which runs from 21st to 23rd February.
Low Frequency in Stereo will be returning to Germany for a series of 5 gigs in late September.
Low Frequency will be palying at USF Verftet in Bergen on 13th August together with Datarock and Herr Nilsson.
www.lowfrequencyinstereo.com /news.php   (1735 words)

  
 Defra, UK - Environmental Protection - Noise - Research - Low Frequency   (Site not responding. Last check: )
Methodology for the assessment of low frequency noise
The University of Salford was commissioned by Defra to develop a proposed criteria and methodology for the assessment of low frequency noise complaints.
Low frequency noise causes extreme distress to a number of people who are sensitive to its effects.
www.defra.gov.uk /environment/noise/research/lowfrequency/index.htm   (414 words)

  
 Ghosts created by low frequency sounds
His first thought was that there might be low frequency sound waves coming from somewhere in the laboratory -- subsonic sounds that can be seen (in the form of surrounding vibrations) but not heard.
Tandy believes that the low frequency sound also caused his late-night spectral visitation: the cold chills, the sense of paranoia and distress, the hallucinatory figure glimpsed creeping in the shadows.
The ancient architects of these tombs may not have understood infrasound frequencies and Helmholtz resonance, but spookiness was a desirable feature for a tomb, for the purpose of instilling reverence for the dead and discouraging grave-robbers.
www.meta-religion.com /Paranormale/Ghost/ghosts_created_by_low_frequency.htm   (1159 words)

  
 Low Frequency Noise, Vibration and Active Control
The considerable and growing interest in the phenomena of low frequency noise and vibration and their powerful effects on man, animals and the environment, spreads across several disciplines; studies of these topics are to be found at present in the periodical literature of acoustics, geophysics, architecture, civil and mechanical engineering, psychology and zoology.
• propagation of infrasound and low frequency noise in the atmosphere;
• interaction of low frequency noise and vibration: vibrations caused by noise, radiation of noise from vibrating structures;
www.multi-science.co.uk /lowfreq.htm   (569 words)

  
 Low Frequency Microphonics   (Site not responding. Last check: )
In the case of LIGO, there is a rather ubiquitous low frequency noise background whether from seismic movement, overhead aviation, trucks in nearby roads, etc. and unfortunately these are sources that are quite intrinsic to the planet Earth and our own civilization.
The heart of this low frequency microphone will be a differential pressure sensor, measuring the compressions and expansions of air that constitute an incident acoustic wave.
Another feature of this interface circuit must be a filter so that a passband of frequencies can be defined in which the tranducer is sensitive, and two different sensors can then have a border on a certain cutoff frequency, and by joining their signals, we increase our bandwidth.
geco.phys.columbia.edu /~szairis/abstract.html   (720 words)

  
 THE LOW FREQUENCY IN STEREO
The Low Frequency in Stereo, from Haugesund, Norway, is called the band with one foot in Pompeii and one in Space.
The release of “The Last Temptation of… the Low Frequency in Stereo vol 1” in march ‘06 made good critics all over the world, and Low Frequency in Stereo got nominated for the Norwegian Grammy Award “Spellemannsprisen” 2006 in the category of “Best Rock Album”.
Due to all this, The Low Frequency in Stereo wants to give their audience more.
www.lowfrequencyinstereo.com /press.htm   (368 words)

  
 Correcting Low Frequency Phase Distortion
For example, for a value of F0 of 100 Hz, as could be attained by a low pitched male voice, a filter having a -3dB frequency of as low as 10 Hz could may cause some appreciable waveform distortion, depending on the shape of the waveform and the strength of the filter.
Thus with a factor of 2.5, an audio system with a -3 dB frequency of 40 Hz could be corrected to a new -3 dB frequency of roughly 16 Hz, with the precise extent of the compensation depending on the strength (number of poles) of the high-pass filtering in the audio system.
In the lower three panels (B, C and D), a compensator with N = 2.5 is employed to reduce the distortion, with the zero introduced by the compensator increasing in frequency from B to C, and at an intermediate value in D that appeared to the writer to yield a minimum distortion.
www.rothenberg.org /Phase/index.htm   (2007 words)

  
 BWEA - Low frequency noise and wind turbines
The frequency, or 'pitch', of a sound is measured in cycles per second (or 'Hertz' (Hz)) although most noise in the environment contains energy at many different frequencies combining together to give it its overall character.
The consequence of these developments was to dramatically reduce tower interaction effects, and the generation of high levels of low frequency noise by wind turbines.
Wind turbines are not, therefore, a significant source of low frequency or infrasonic noise but, as with noise from any other sound source, the high frequency components are reduced when heard from a distance and overall levels are very low.
www.bwea.com /ref/lowfrequencynoise.html   (729 words)

  
 Extremely Low Frequency Communications Program - United States Nuclear Forces
The ELF frequency range is critically important to the Navy because of its value in providing a way to communicate with submerged submarines.
Frequencies in the ELF range, however, can be received considerably deeper, and broadcasts using this mode provide a primary link between the nation's commander-in-chief and the submarine force.
Extremely low frequency continues to be an essential communications system to support strategic and tactical submarine forces.
www.fas.org /nuke/guide/usa/c3i/elf.htm   (509 words)

  
 Extremely low frequency (ELF) fields (EHC 35, 1984)   (Site not responding. Last check: )
To characterize ELF fields, the strength, frequency, and orientation of the electric and magnetic fields have to be determined.
The preliminary nature of the epidemiological findings, the low levels of exposure, and the relatively small increment in the reported incidence of any effects, suggest that, though the epidemiological data cannot be dismissed, there must be considerable study before they can serve as useful inputs for risk assessment.
The alternating fields at low frequency are related to thunderstorm activity and magnetic pulsations that produce currents within the Earth (telluric currents).
www.inchem.org /documents/ehc/ehc/ehc35.htm   (16444 words)

  
 Low-Frequency, Nonlinear Oscillations of the Wind-Driven Circulation
Each low frequency cycle in Figure 3 corresponds to a large loop around one wing of the butterfly.
These fluxes vacillate on the low frequency time scale and lead to the waxing and waning of the recirculation gyres.
At the onset of aperiodic behavior, we again see the appearance of low frequency, large amplitude cyclic fluctuations at time scales of O(a few hundred days), superimposed on mesoscale variability with a period of roughly 50 days.
www.aoml.noaa.gov /phod/acvp/meacham.htm   (1611 words)

  
 Low Frequency Inductance
Inductive behavior which appears in the high frequency range is fairly easily explained by instrumental artifacts, or by the inductance of the electrode, or the inductance of the connecting wires.
In contrast to the "high frequency" inductor, the value of L which fits this data is in the range of one Henry, or perhaps larger.
The most quoted explanation for this low frequency inductive behavior is an adsorption process at the electrode surface.
www.consultrsr.com /resources/eis/induct2.htm   (284 words)

  
 Ask Dr. SETI: Low Frequency SETI
But the power available at low frequencies is so huge, I wonder if searching those frequencies might give us the first hint that a civilization exists, even if we would not have the resolution to know where it was coming from.
The problem with very low frequency SETI is that the ionosphere effectively blocks most of the signal energy which might otherwise reach Earth.
But they tend to underscore why higher frequencies are favored for space communications in general, and point-to-point interstellar contact in particular.
www.setileague.org /askdr/lowfreq.htm   (579 words)

  
 MAPP Online - Low Frequency Polar Data
The wavelength of sound at 30 Hz is 11.4 meters (38 feet), and therefore the anechoic wedges would need to be on the order of 10 to 20 feet long in order to absorb, and not reflect, low frequency energy.
The ground is known as a half plane, and on axis to a single loudspeaker it creates a very accurate measurement of the frequency response compared with a single loudspeaker measured in an anechoic chamber.
A general rule of thumb used in Boundary Element Modeling is to use a mesh grid that corresponds to 1/10th of a wavelength of the highest frequency predicted.
www.meyersound.com /products/mapponline/low_frequency_polar_data.htm   (922 words)

  
 Vibration Control & Noise Control Solutions
Low Frequency Mounts’ unique design bonds a steel spring inside a matrix of oil/ozone-resistant neoprene.
The springs absorb low frequency vibrations, slowing and passing them on to the resilient neoprene.
Low Frequency Mounts are made for your toughest vibration applications.
www.novibes.com /vibration/productinfo/lowfreqmnts/index.asp   (147 words)

  
 Extremely Low Frequency Radiation/Power Lines   (Site not responding. Last check: )
Exposures to many EMF frequencies are increasing significantly as technology advances unabated and new applications are found.
The frequency is simply the number of oscillations in the wave per unit time, measured in units of hertz (1 Hz = 1 cycle per second), and the wavelength is the distance travelled by the wave in one oscillation (or cycle).
At frequencies this low, the wavelengths in air are very long (6000 km at 50 Hz and 5000 km at 60 Hz) and, in practical situations, the electric and magnetic fields act independently of one another and are measured separately.
hps.org /hpspublications/articles/elfinfosheet.html   (1670 words)

  
 FAQ: Is Low Frequency Noise a Problem for Wind Turbines?
1) Because of the low rotational rates of the turbine blades, the peak acoustic energy radiated by large wind turbines is in the infrasonic range with a peak in the 8-12 Hz range.
2) The levels of infrasound radiated by the largest wind turbines are very low in comparison to other sources of acoustic energy in this frequency range such as sonic booms, shock waves from explosions, etc. The danger of hearing damage from wind turbine low-frequency emissions is remote to non-existent.
By contrast, the primary concern there has been the much higher frequency broadband and discrete frequency noise associated with the unsteady aerodynamic forces on the blades, often in the blade tips.
www.awea.org /faq/noise-lf.html   (491 words)

  
 Rethinking Low Frequency Caps
This power is frequently put to use, with many planners (and networks) capping frequency at three exposures.
One person told me that he found this to be the case most often for brands with low initial awareness, suggesting that multiple exposures have a branding effect that eventually culminates in a click and a sale.
If this is true, then low frequency caps can be counterproductive for all but the narrowest of direct response initiatives.
www.clickz.com /showPage.html?page=837471   (796 words)

  
 Low Frequency Therapeutic Equipment Manufacturers & Suppliers
View Low Frequency Therapeutic Equipment Suppliers List
Low Frequency Therapeutic Equipment Products: Source for Low Frequency Therapeutic Equipment manufacturers at Global Sources.
The featured China Low Frequency Therapeutic Equipment manufacturers and featured Taiwan Low Frequency Therapeutic Equipment manufacturers listed here are sourced by the Global Sources team of industry experts.
www.globalsources.com /manufacturers/Low-Frequency-Therapeutic-Equipment.html   (490 words)

  
 Low Frequency Radio Astronomy from Space
At these frequencies ionospheric phase and amplitude fluctuations become so large that even the strongest calibration sources become decorrelated and selfcal techniques fail.
The plasma frequency of the ionosphere is ~15 MHz on the day side of the earth near sunspot maximum and ~10 MHz on the night side near sunspot minimum, making the layer opaque to all lower frequencies.
Low Frequency Astrophysics from Space; Kassim & Weiler 1990).
rsd-www.nrl.navy.mil /7213/weiler/lfraspce.html   (641 words)

  
 The Low Frequency Instrument
The number of detectors in each band was chosen as a trade-off between the instrumental sensitivity (which varies with frequency), and the desire to obtain the highest final sensitivity at
The design of the feedhorns, though straightforward, must be optimized to provide low sidelobe level, low loss, and good stability.
As noted before, the dominant heat input into the focal plane is due to power dissipation in the MMICs; since this fact drives the thermal design of the payload module significantly, it is desirable to reduce it as far as possible.
www.rssd.esa.int /SA/PLANCK/include/payl/node6.html   (882 words)

  
 Amazon.com: Buttkicker BK-LFEKit Low Frequency Effect Kit with Amplifier: Electronics   (Site not responding. Last check: )
The ButtKicker LFE (low frequency effects) functions similar to a loudspeaker, but instead of moving a cone and transferring sound waves through the air, it uses a patented magnetic suspension system to attach to seats and floors, thus sending the low frequency sound directly into the listener's body.
But the Buttkicker is the best; the Clarks are less intense and less concentrated in the low frequencies, the Auras are $20 units with all that entails (such as lack of shake and lack of finess) and the Crowsons are purely under-couch devices.
The high and low pass filters work pretty well, my only complaint is I need to put a low frequency equalizer on it to even out the sounds.
www.amazon.com /Buttkicker-BK-LFEKit-Frequency-Effect-Amplifier/dp/B0006FK42S   (2116 words)

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