Evaluation of the intensity method of sound power determination

Zyl, B. G. van; Anderson, F.

doi:10.1121/1.380492

Cited by 16 publications

(4 citation statements)

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“…Although there have been "intensity meters" constructed (e.g., see [55-6l] and there is current interest [62] in this method of sound power determination, intensity meters are not commercially available and there are certain difficulties in applying eq. ( 49) to real-world situations [63]• It also is of interest to consider the energy density (or total energy per unit volume), w4 in the medium through which the sound is propagating: 41 -S?…”

Section: Generalmentioning

confidence: 99%

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Noise emission measurements for regulatory purposes

Flynn¹,

Leasure²,

Rubin³

et al. 1977

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A review is given of the measurement needs attendant to regulation of the noise generated and emitted by commercial products.The emphasis is primarily on measurement procedures for use in conjunction with point-of-sale regulations as opposed to regulations on the noise which a source actually emits when in operation.The report is divided into three major parts. Part I is a discussion of overall measurement requirements and the type of data and information which are needed in order to promulgate regulations based on appropriate measurement techniques.Part II is designed as a checklist for the evaluation of the suitability of a noise measurement standard for a particular class of products or, in the absence of a suitable standard, as a framework for development of one.The intent is to identify and discuss in some detail those factors which can impact on the accuracy, precision, and applicability of a noise measurement process.Part III consists of a series of flow charts depicting the development of appropriate procedures for the measurement of product noise emission.

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Section: Generalmentioning

confidence: 99%

“…If the piston oscillates in the z-direction with a velocity Ue , the sound pressure on the z-axis is (see, e.g.,[6U,65]) £_ = pcU P icu(z/c -t) ico [ (1 + z2/a2)^^a/c -t] -e P (62) Utilizing eq. ( 44), the particle velocity on the z-axis and in the z-direction is…”

mentioning

confidence: 99%

Noise emission measurements for regulatory purposes

Flynn¹,

Leasure²,

Rubin³

et al. 1977

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“…[3][4][5][6][7][8][9][10] Recently, efforts in this area have concentrated on the development of measurement techniques and devices. With the advent of new signal processing techniques and advances in transducer technology, intensity measurement devices have been improved to make them more reliable, accurate, and compact.…”

Section: Introductionmentioning

confidence: 99%

Development of an accelerometer-based underwater acoustic intensity sensor

Kim¹,

Gabrielson²,

Lauchle³

2004

The Journal of the Acoustical Society of America

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An underwater acoustic intensity sensor is described. This sensor derives acoustic intensity from simultaneous, co-located measurement of the acoustic pressure and one component of the acoustic particle acceleration vector. The sensor consists of a pressure transducer in the form of a hollow piezoceramic cylinder and a pair of miniature accelerometers mounted inside the cylinder. Since this sensor derives acoustic intensity from measurement of acoustic pressure and acoustic particle acceleration, it is called a p-a intensity probe. The sensor is ballasted to be nearly neutrally buoyant. It is desirable for the accelerometers to measure only the rigid body motion of the assembled probe and for the effective centers of the pressure sensor and accelerometer to be coincident. This is achieved by symmetric disposition of a pair of accelerometers inside the ceramic cylinder. The response of the intensity probe is determined by comparison with a reference hydrophone in a predominantly reactive acoustic field.

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“…Consider a sound insulation test performed on a door (A = 2m 2) contained in a filler wall with a surface area AF = 6m 2. The wall is known to have a sound reduction index RF of 34 dB at 125 Hz and 41 dB at 500 Hz while the door is expected to yield approximate sound reduction indices R of 33 and 36 dB, respectivel)~ The power transmitted into a reverberation room ofvohme 210 m 3 is to be determined with a sound intensity meter which has phase mismatch errors of 0 10. and 0.25 degrees at 125 Hz and 500 Hz, respectively.…”

mentioning

confidence: 99%

Sound Transmission Analysis in Reactive Fields by Sound Intensimetry

Zyl¹,

Erasmus²

1987

Noise Control Eng. J.

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This paper investigates the practical requirements for sound transmission analysis in reactive fields by sound intensimetry. It is shown that phase mismatch, which determines the common mode rejection index of the measurement system, sets a limit to the reactivity level at which measurements can be performed accurately. An expression is derived which predicts the reactivity at the surface of a test object surrounded by flanking surfaces. It is shown how the minimum microphone spacing or, alternatively, the minimum amount of absorption in the receiving room may be calculated from intensity meter performance figures. Supported by experimental findings, this study proves that practical intensity meters can be used effectively in performing sound transmission analysis in highly reactive receiving rooms such as reverberation chambers. Nomenclature Roman symbolsA Surface area of test panel AF Area of flanking surface c The velocity of sound in air f Frequency in Hz h Fraction of the total power transmitted by test panel hF Flanking factor, (flanking power)/(direct power) lo Intensity reference value, 10-l~W/m2 IA Active sound intensity Io Direct intensity transmitted by test panel into receiving room I R Reactive sound intensity k The wave number Le Intensity measurement error in dB Lem Limit specified for sound intensity error in dB Lear Finite distance approximation error in dB L/ Sound intensity level in dB re lpW/m 2 L/m Residual sound intensity level in dB indicated by a sound intensity meter with the probe situated in a purely reactive field LP Sound pressure level in dB re 20 p~Pa LR Reactivity of sound field in dB LRm Common mode rejection index of measurement system in dB LRmo Common mode rejection index in dB, for a microphone spacing Aro Po Pressure reference value, 20 }xPa P(r) Root mean square value of sound pressure at a distance r Po Direct field sound pressure PR Reverberant field sound pressure PRo Reverberant pressure at center of receiving room R Sound transmission loss of test panel R F Sound transmission loss of flanking wall S Receiving room surface area ur Particle velocity in direction r W Total power transmitted into receiving room Greek symbols ot Average sound absorption coefficient of boundary surfaces in receiving room AL Safety margin LRm -LR required to ensure sound intensity error does not exceed Lem dB Ar Spacing between intensity probe microphone centers Aro Microphone spacing for which common mode rejection index is known Volume 28/Number 3 113

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Evaluation of the intensity method of sound power determination

Cited by 16 publications

References 0 publications

Noise emission measurements for regulatory purposes

Noise emission measurements for regulatory purposes

Development of an accelerometer-based underwater acoustic intensity sensor

Sound Transmission Analysis in Reactive Fields by Sound Intensimetry

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