A new acoustic three dimensional intensity and energy density probe (original) (raw)
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Vector intensity measurement with a rigid spherical microphone array in a vehicle cabin
The Journal of the Acoustical Society of America, 2008
Acoustics 08 Paris vehicle cabin are presented. The measurement equipment developed by Nittobo was used in previous demonstrations to visualize the acoustic field using a beamforming technique superimposed on a picture from an on-board camera. In the present study intensity reconstructions are shown and are successful in locating and quantifying sources, demonstrating the usefulness of this technique in an enclosed space like a vehicle cabin, aircraft cabin, small room, etc. This work was supported by the US Office of Naval Research and Nittobo Acoustic Engineering Co. Ltd.
3D Acoustic Field Intensity Probe Design and Measurements
Archives of Acoustics, 2016
The aim of this paper is two-fold. First, some basic notions on acoustic field intensity and its measurement are shortly recalled. Then, the equipment and the measurement procedure used in the sound intensity in the performed research study are described. The second goal is to present details of the design of the engineered 3D intensity probe, as well as the algorithms developed and applied for that purpose. Results of the intensity probe measurements along with the calibration procedure are then contained and discussed. Comparison between the engineered and the reference commercial probe confirms that the designed construction is applicable to the sound field intensity measurements with a sufficient effectiveness.
Visualization Of Energetic Acoustic FieldInside Cabins
WIT Transactions on the Built Environment, 1997
The article presents the application of the sound intensity (SI) technique to the measurement of the acoustic radiation of ship cabin partitions. On the basis of the near field acoustic intensity measurement with the fixed point method, the distribution of spatial intensity vectors in a measurement plane is presented. As a result of the investigation, a three-dimensional flow map of active intensity vectors distributed in crow cabin is graphically illustrated in different forms. The measurement technique described, as well as the method of graphical presentation of results, can enrich the knowledge of the mechanism of acoustic energy flux inside small enclosures. There is also technique that can be powerful tool in noise abatement education.
2014
Estimating the Acoustic Power of Sources in Nonideal Enclosures Using Generalized Acoustic Energy Density Daniel R. Marquez Department of Physics and Astronomy, BYU Master of Science Sound power measurements of acoustic sources are generally made in reverberation or anechoic chambers using acoustic pressure measurements as outlined in specific ISO or other standards. A reverberation chamber produces an approximate diffuse-field condition, wherein the sound power is determined from the spatially averaged squared pressure. An anechoic chamber produces an approximate free-field condition, wherein the sound power is estimated from squared pressure over an enveloping measurement surface. However, in many cases it is desirable to estimate sound power within nonideal semi-reverberant spaces. In these environments, both direct and reverberant energies may contribute significantly to the total acoustic field. This paper introduces two measurement methods that utilize a weighted combination o...
Acoustic Source Localization in Aircraft Interiors Using Microphone Array Technologies
12th AIAA/CEAS Aeroacoustics Conference (27th AIAA Aeroacoustics Conference), 2006
Using three microphone array configurations at two aircraft body stations on a Boeing 777-300ER flight test, the acoustic radiation characteristics of the sidewall and outboard floor system are investigated by experimental measurement. Analysis of the experimental data is performed using sound intensity calculations for closely spaced microphones, PATCH Inverse Boundary Element Nearfield Acoustic Holography, and Spherical Nearfield Acoustic Holography. Each method is compared assessing strengths and weaknesses, evaluating source identification capability for both broadband and narrowband sources, evaluating sources during transient and steady-state conditions, and quantifying field reconstruction continuity using multiple array positions.
The Journal of the Acoustical Society of America, 2005
This paper describes a full vector intensity probe which advances the field of sound intensity and sound source direction estimation using six matched rotating and variable directional microphones. The probe has three pairs of microphones at an equal spacing of 30 mm that are set up in each of the x, y, and z directions and share the same observation point. The calibration method using the rotating microphone system is effective to correct position errors in the y-and z-axes microphone pairs. Sound intensity measurements using the variable directional microphone method can locate with accuracy a sound source, i.e., the structure parts radiating most acoustic energy. The system can find the maximum sound intensity level and beamwidth of the major lobe, and the peak sound intensity levels of the minor lobes. Therefore, a procedure for sound power determination based on minimum measurement data is theoretically and experimentally discussed. Consequently, it is possible to reconstruct only parts of the system emitting the most noise and measure efficiently the sound power level.
Array technology for acoustic wave field analysis in enclosures
The Journal of the Acoustical Society of America, 1997
A method is proposed to calculate and measure impulse responses in an enclosure along closely spaced receiver arrays. Hence, instead of using a sparse distribution of receiver positions with single microphones, as is common practice now, arrays of microphones are applied to register the complex sound fields within enclosures. This way, there is a strong spatial correlation between adjacent responses, enabling one to analyze individual reflected wavefronts. It is shown that visualization of the recorded data in a two-dimensional domain, defined by detector position and travel time, gives a significantly improved insight in the structure of complex sound fields. This insight is further increased by applying the linear Radon transform (plane wave decomposition), yielding a representation of the data in the so-called ray parameter versus intercept time domain.
Design and Calibration Tests of an Active Sound Intensity Probe
Advances in Acoustics and Vibration, 2008
The paper presents an active sound intensity probe that can be used for sound source localization in standing wave fields. The probe consists of a sound hard tube that is terminated by a loudspeaker and an integrated pair of microphones. The microphones are used to decompose the standing wave field inside the tube into its incident and reflected part. The latter is cancelled by an adaptive controller that calculates proper driving signals for the loudspeaker. If the open end of the actively controlled tube is placed close to a vibrating surface, the radiated sound intensity can be determined by measuring the cross spectral density between the two microphones. A one-dimensional free field can be realized effectively, as first experiments performed on a simplified test bed have shown. Further tests proved that a prototype of the novel sound intensity probe can be calibrated.