The steady-state evaluation of small anechoic chambers

Bell, E.C.; Hulley, L. N.; Mazumder, N. C.

doi:10.1016/0003-682x(73)90019-4

Cited by 7 publications

(4 citation statements)

References 10 publications

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“…The most commonly used test method is the inverse distance draw-away test, or divergence loss test, where the measured pressure should be inversely proportional to the source-receiver separation. 1,2,12,[15][16][17][18][19][20][21][22][23][24][25] Whereas the carousel method gives an indication of the deviations in a plane, the divergence loss test assesses the deviations along a room dimension, or radial path from a source. A comparison of the two methods found differences between the results, but the drawaway test was in accord with low-frequency impedance tube testing of the absorbent material.…”

Section: Measuring the Free Fieldmentioning

confidence: 99%

Qualification of Free-Field Rooms - The Need for a Standard

LORD

2023

It's How Loud? Are You Sure? 2003

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The free-field room or anechoic chamber is one of the basic test environments used for acoustical investigations of sound sources and receivers. In a primary laboratory the anechoic chamber provides a facility for free-field calibration of microphones. Understanding the interaction of an acoustic wave with the geometrical configuration of material surfaces and the absorption of sound in those materials has led to a range of designs for linings (predominantly wedges) of these rooms. However, despite there being many free-field facilities worldwide, there exists no definitive method for determining and therefore defining their performance. International standards dealing with sound power measurements, ISO 3745 Annex A and similar ANSI S12.35 Part 9, give procedures for qualifying anechoic test rooms. These rely on a draw-away test to assess the free-field conditions, determining the extent to which a spherically radiating wave deviates from the ideal inverse law for pressure. This is a time consuming test which has been found to be difficult to perform and so several researchers have demonstrated other methods of evaluating the free field by using intensity, constant separation or tone-burst techniques.There is a need for standardisation and NPL have been involved in a project to assess these methods, which should ultimately result in a recommendation to ISO.

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Section: Measuring the Free Fieldmentioning

confidence: 99%

Qualification of Free-Field Rooms - The Need for a Standard

LORD

2023

It's How Loud? Are You Sure? 2003

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“…The anechoic chamber at the LMA has inner dimensions of 5.4 × 6.3 × 11.4m 3 decibelf rance [8]. Thecut-off frequencyofthe chamber of 75 Hz wasdetermined by decibelf rance using impedancetube measurements on the acoustic lining elements butneglecting the iron wire frame.…”

Section: Determination Of the Room Characteristicsmentioning

confidence: 99%

“…To characterize the anechoic chamber the properties of the sound source -a coustic center and source strength -must be known. Instead of using an analog compensation method [3,4] or am athematical compensation Received15June 2007, accepted 4November 2007 method [5,6] here an umerical model for the entire bass reflexb ox wasu sed to obtain the acoustic free-field of the sound source. The precise knowledge of the acoustic source enables the determination of the sound field reflected by the acoustic lining.…”

Section: Introductionmentioning

confidence: 99%

Acoustical Behavior of the Large Anechoic Chamber at the Laboratoire de Mécanique et d'Acoustique in the Low Frequency Range

Schneider¹,

Kern²

2008

Acta Acustica united with Acustica

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It is of vital importance to have detailed information about the characteristics of an anechoic chamber,since any imperfections lead to deviations from free-field conditions and will perturb measurements. In the present paper the behavior of the large anechoic chamber at the LMA is studied in the 20 to 200 Hz frequencyr ange. The response to pure-tone excitation, generated by an open vented box, wasrecorded along twolines parallel to the walls. An umerical model for the radiating sound source wasu sed to determine the strength of the source and its center.T he region in the chamber where the deviation from free-field conditions wasl ess than the allowed 1.5dBwas determined, based on the experimental data. Its wasestablished that even above the cut-off frequency, deviations greater than the allowed 1.5d Bo ccurred. Ad oor in the anechoic chamber wasi dentified as at least one of the sources of these imperfections.

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“…Useful references concerning the design and qualification of anechoic chambers include [18][19][20][21][22][23][24][25][26].…”

Section: Utmentioning

confidence: 99%

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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The steady-state evaluation of small anechoic chambers

Cited by 7 publications

References 10 publications

Qualification of Free-Field Rooms - The Need for a Standard

Qualification of Free-Field Rooms - The Need for a Standard

Acoustical Behavior of the Large Anechoic Chamber at the Laboratoire de Mécanique et d'Acoustique in the Low Frequency Range

Noise emission measurements for regulatory purposes

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