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Topic: Acoustic intensity

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Sound

	[No title] (Site not responding. Last check: 2007-10-23)
		Acoustic is used when the term being qualified designates something that has the properties, dimensions, or physical characteristics associated with sound waves; acoustical is used when the term being qualified does not designate explicitly something that has such properties, dimensions, or physical characteristics.
		Acoustic Wavelength The acoustic wavelength is the distance between any two adjacent points at which the phase, at the same instant, differs by 2¹; it corresponds to the distance traveled by the wave during one cycle; l = c/f, where l is the wavelength, c is the speed of sound, and f is the frequency.
		Refractive Index (Measurable Quantity) The acoustic refractive index of a medium, such as tissue, is the ratio of the phase speed in a referenced medium, such as distilled water at 20¡C, to the phase speed of the same wave in the specified medium at the same temperature.
	ultrasonics.wustl.edu /Database/Dictionary.text (11230 words)

	Sound pressure - Wikipedia, the free encyclopedia
		For small amplitudes, sound pressure and particle velocity are linearly related and their ratio is the acoustic impedance.
		The acoustic impedance depends on both the characteristics of the wave and the medium.
		The local instantaneous sound intensity is the product of the sound pressure and the acoustic partical velocity and is, therefore, a vector quantity.
	en.wikipedia.org /wiki/Sound_pressure (895 words)

	2. KEY PHYSICAL QUANTITIES
		Acoustic intensity (I) is defined as the amount of energy per second (power), passing through unit area normal to the direction in which the acoustic wave is propagated.
		Acoustic intensity is analogous to electrical power on the basis of the amount of energy and the time it flows or is used.
		The speed of acoustic waves in the sea is denoted by the symbol c and is measured in metres/second (m/s).
	www.fao.org /docrep/X5818E/x5818e03.htm (3990 words)

	[No title]
		Acoustic waves can be described either by the speed at which a small piece of the medium vibrates, called the particle velocity, or by the corresponding pressure associated with the vibration.
		Acoustic Propagation Acoustic vibrations propagate as waves, that is, they travel away from their source and lose energy by attenuation (heating of the media) and by spreading.
		Fishing vessels and acoustic deterrent devices have moderate source levels but may represent at least local acoustic annoyances, although in the case of ADDs there is a significant benefit from the reduction of marine mammal bycatch.
	www.acousticecology.org /docs/IWC56-hildebrandnoise.doc (1910 words)

	PRINCIPLES OF UNDERWATER SOUND Chapter 8
		Acoustic energy, while lacking the propagation speed of electromagnetic waves, is capable of being transmitted through the sea to distances that are operationally significant.
		The intensity is proportional to the square of the acoustic pressure.
		When calculating the acoustic signal resulting from a signal of interest superimposed on the ambient background noise of the ocean (signal to noise ratio), this calculation must be made using signals of the same frequency to be valid.
	www.fas.org /man/dod-101/navy/docs/fun/part08.htm (17405 words)

	Moulton Lectures
		Generally for earphone and noise level measurements the ordinate is a function of the acoustic intensity of the sound emitted from the noise source or from the earphone.
		Acoustic Intensity I of a sound wave is defined as the average rate of change of energy transmitted per unit area in the direction of wave propagation.
		Where I is the measured acoustic intensity and P the measured pressure.
	www.moultonworld.pwp.blueyonder.co.uk /Lecture3_page.htm (1276 words)

	Ultrasound therapeutic device - Patent 6860852
		Proper acoustic power outputs and treatment durations must be specified, monitored, and updated in a manner most beneficial for the treatment goals for the unique individual patient, after fully understanding and processing data pertaining to the target tissue, intermediate tissue, and tissue depths.
		Next, intensity and treatment duration end points are examined based on the simulation results to determine optimum values for generating the product dosage, wherein the resulting product dosage is processed to determine whether it falls within an acceptable range defined by predetermined minimum and maximum product dosage values.
		Once the acoustic coupling returns to an acceptable level (by the user having placed the treatment head 16 back in contact with a patient's skin), the feedback loop is restarted and normal operation resumes.
	www.freepatentsonline.com /6860852.html (8902 words)

	1999; Measurement of incident and emitted acoustic intensity in the ear canal (Site not responding. Last check: 2007-10-23)
		Acoustic intensity of incident and emitted sound waves were measured in adult human ear canals using a variation of the random-excitation technique reported by Seybert and Ross (J Acoust Soc Am 61:1362-1370).
		Data analysis performed in the frequency domain determined the magnitude and phase of the emitted intensity, the incident intensity and the ratio of the two, i.e., the power reflection coefficient, as a function of position along the ear canal.
		Pressure, total intensity, I, E, and R will be presented as functions of frequency and position in the ear canal to demonstrate their relationships with one another and the usefulness of each parameter.
	www.aro.org /archives/1999/803.html (344 words)

	4. FORMING THE ACOUSTIC EQUATIONS
		This is the axial transmitted acoustic intensity at the reference distance of one metre from the transducer face.
		Therefore the acoustic intensity on the axis of the beam decreases in proportion to the distance squared.
		For the present purpose we assume that all the acoustic intensity at 200 m is returned towards the transducer.
	www.fao.org /docrep/X5818E/x5818e05.htm (3349 words)

	Acoustic Parameters (Site not responding. Last check: 2007-10-23)
		Notice that acoustic impedance is measured in Rayles.
		We will see later in our discussion of acoustic reflection that the relative acoustic impedance is an important parameter that controls the magnitude and nature of reflection from an interface between two different materials.
		For water this standard intensity is the intensity resulting from the passage of a plane wave with an mean square pressure (p) of 1
	freespace.virgin.net /mark.davidson3/parameters/parameters.html (373 words)

	Fachbereich Physik der TU Darmstadt
		This is a cavitation field being produced by a radially symmetric sound field of approximately 23 kHz.
		The frequency is scaled relative to the driving frequency of 71 kHz: Subharmonic frequencies and their harmonics appear upon increasing the driving amplitude.
		Above you see an image of a strange attractors from acoustic cavitation noise in color-coded 3D.
	www.physik.tu-darmstadt.de /nlp/cavitation.html (212 words)

	Sound Intensity Mapping (Site not responding. Last check: 2007-10-23)
		Sound intensity is the rate at which sound energy...
		The sound intensity field represents the direction and the...
		acoustical properties like particle velocity, sound power and sound intensity.
	www.gislinx.com /soundintensitymapping.html (205 words)

	High Performance Wireless Research and Education Network
		Values of acoustic intensity for biological levels (4 and 5) are 4.9 and 2.1, respectively for the15 March 0700 recording.
		To compute the relative biological acoustic intensity for bands with biological information, values in levels 4 and 5 are summed and divided by the acoustic intensity for the full sonogram (level 12).
		The resulting biological intensity values are 5.84 (7.0/1.2) for the March recording and 8.43 (29.6/3.5) for the May recording illustrating that the May recording has a higher biological content than the March recording.
	hpwren.ucsd.edu /news/050210.html (839 words)

	Penn State - Graduate Program in Acoustics - Laboratories
		It was developed to study the fluid mechanics and acoustics of the complex flow field beneath a moving automobile (or any other ground effects vehicle).
		Typically, the test bodies are acoustic sensors such as pressure, or pressure gradient hydrophones which may be exposed to ocean currents in real applications.
		The facility can also be used to measure the acoustic impedance of materials, pinpoint defects and faults inside bulk materials and structural components, identify sources of noise emission and diffraction, and identify paths of structural wave propagation.
	www.acs.psu.edu /Faculty/laboratories.htm (1966 words)

	Acoustic Monitor - Three dimensional acoustic intensity (Site not responding. Last check: 2007-10-23)
		Any localized noise field associated with sources within the enclosure is located and the absolute intensity measured using verified algorithms.
		This type of acoustic noise generation field is traditionally monitored by placing microphones at various locations, taking a measurement then moving microphones to a different location for further data.
		It can extract the intensity of local internal noise sources from the reverberant noise field in the enclosure or space, and extracts signals totally masked by background noise (signals having intensities 25 to 45 dB below the ambient background).
	www.grdi.com /BatScan_HTM/Technology.htm (579 words)

	Measuring the in-situ airborne sound insulation using the acoustic intensity technique - NRC-IRC
		Measuring the in-situ airborne sound insulation using the acoustic intensity technique
		Currently, the ASTM and ISO standards organizations are writing standards to facilitate the measurement of airborne sound insulation using the acoustic intensity technique.
		Working groups in both organizations have nearly completed prescriptions for applying the technique under laboratory conditions where there is suppressed flanking transmission.
	irc.nrc-cnrc.gc.ca /pubs/fulltext/nrcc43675 (102 words)

	Calibration And Validation Of An Interfacial Acoustic Intensity Probe (ResearchIndex) (Site not responding. Last check: 2007-10-23)
		This method is widely used, but the equipment is expensive and the phase responses of the microphones and the measurement equipment must be precisely matched.
		1 Measurement of acoustic intensity using the cross-spectral d..
		1 Calibration and verification of an acoustic intensity measur..
	citeseer.ist.psu.edu /470568.html (595 words)

	Spectral Dynamics - STARAcoustics Brochure
		STARAcoustics is a complete stand alone acoustic intensity program for use with many other multi-channel FFT instruments or real-time octave analyzers and microphone probes.
		New and occasional users can guide themselves step-by-step through the acoustic intensity process by referring to the Show Assistant, a process-oriented task list.
		Narrowband cross spectra and auto power data is automatically converted to Intensity and Sound Pressure datatypes respectively, synthesize data into 1/1 octave, 1 /3 octave, or user-defined bands.
	www.spectraldynamics.com /staracoustics.htm (987 words)

	Intensity-dependent acoustic absorption in dielectrics: I. Low intensities
		An investigation is undertaken of the extent to which the Landau and Rumer procedure (1937) for calculating acoustic absorption in dielectrics is invalidated by its assumption that the thermal phonons are in equilibrium.
		It is shown that this assumption will break down in pure materials at low temperatures for sufficiently high acoustic intensities and frequencies, and that in several such materials at T approximately 10K a substantial change in the 'low intensity' acoustic relaxation time may be expected for intensities approximately 10
		It is suggested that measurement of this effect could be of use in distinguishing between energy-conserving and non-conserving acoustic interaction processes, and in providing an independent estimate of thermal-phonon relaxation times.
	stacks.iop.org /0022-3719/7/3692 (261 words)

	Noise Control Engineering Journal Abstracts (Site not responding. Last check: 2007-10-23)
		The performance of the system is illustrated from measurements of acoustic intensity in a plane in front of a loudspeaker mounted in a baffle compared with the calculated acoustic-intensity field produced by a point sound source near a hard reflecting plane.
		The five-degree-of-freedom system allows the acoustic intensity probe to be placed at any point within a 1700 x 1000 x 700-mm space.
		The three orthogonal components of the acoustic-intensity vector at a measurement point may be calculated.
	members.aol.com /NCEJABS/ab420105.html (246 words)

	Sage Technologies - Sound and Vibration Instrumentation
		The dBFA32 Acoustic Intensity Pack (AIP) can be used on a stand-alone basis.
		AIP provides real time analysis of sound pressure and sound intensity yielding autospectra, cross spectra, coherence, active and reactive intensity and free-field sound intensity.
		A remote control for the intensity probe is also available.
	www.sagetechnologies.com /prod_detail.cfm?prodcatid=2100017 (115 words)

	Acoustic intensity and power
		Equation 3.15 is a statement of energy conservation for the system and says that the rate of change of energy in a region is equal to the net rate at which energy is carried into the region.
		If apply the relationship between pressure and velocity, equation 3.12, the acoustic intensity is
		over time for a periodic wave, the second term has a mean value of zero and the resulting mean intensity is:
	www.bath.ac.uk /~ensmjc/Notes/MECH0050/html/node16.html (120 words)

	Intensity Mapping
		based program used for the processing and analysis of acoustic intensity and sound pressure data.
		A graphical user interface allows the operator to load, tabulate and display measured intensity/pressure spectra, calculate component sound power levels and generate three dimensional contour maps.
		3D Acoustic Intensity Map: The 3D graphic shows the sound radiation pattern of a hard disk drive recorded for the 2 kHz.
	www.navcon.com /AIMAP.htm (135 words)

	Towards a protocol for measurement of maximum spatial peak temporal average acoustic intensity from diagnostic B mode ...
		Towards a protocol for measurement of maximum spatial peak temporal average acoustic intensity from diagnostic B mode ultrasound scanners in the field
		As the complexity of diagnostic ultrasound equipment has increased, so have the problems of measuring the acoustic outputs of this equipment in the field.
		Measurements made in the field are often made on unfamiliar pieces of equipment and under tight constraints of time.
	stacks.iop.org /0031-9155/38/1611 (479 words)

	Find in a Library: Active control of structural intensity and acoustic radiation of an infinite mindlin plate in an ...
		Find in a Library: Active control of structural intensity and acoustic radiation of an infinite mindlin plate in an acoustic medium
		Active control of structural intensity and acoustic radiation of an infinite mindlin plate in an acoustic medium
		WorldCat is provided by OCLC Online Computer Library Center, Inc. on behalf of its member libraries.
	worldcatlibraries.org /wcpa/ow/f0c140e50a5d34c8a19afeb4da09e526.html (82 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		Energy Citations Database (ECD) Document #5628209 - Acoustic intensity measurement of transformers
		Availability information may be found in the Availability, Publisher, Research Organization, Resource Relation and/or Author (affiliation information) fields and/or via the "Full-text Availability" link.
		Research Reports Center, PO Box 50490, Palo Alto, CA 94303
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=5628209 (153 words)

	Modified Acoustic Intensity Derivation (Site not responding. Last check: 2007-10-23)
		Next: Suggested Convention for Sound Up: Comments on ``Standard Definitions Previous: Introduction
		The acoustic particle velocity in the r direction, U, is in phase with the acoustic pressure, p, everywhere in the far field of a simple acoustic source radiating spherical waves.
		Thus the corresponding equation for the instantaneous intensity should be
	www.acs.psu.edu /users/sparrow/papers/sparrowOEpaper/node2.html (147 words)

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