Browse Prior Art Database

Automatic Sound Power Measurement

IP.com Disclosure Number: IPCOM000045531D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Lanham, TE: AUTHOR

Abstract

Sound power of apparatus under test is automatically measured under computer control by means of a rotating boom carrying a number of microphones supplying sound data to a digital analyzer.

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Automatic Sound Power Measurement

Sound power of apparatus under test is automatically measured under computer control by means of a rotating boom carrying a number of microphones supplying sound data to a digital analyzer.

The apparatus shown in the figure consists of a Bruel and Kjaer 3923 Rotating Microphone boom 1 carrying five microphones 2. An adapter box 3a is connected to receive the acoustic data from the five microphones and transmits it through boom 1. Adapter box 3 receives data from boom 1 and transmits it over individual coaxial cables 4 to a Bruel and Kjaer 2811 Multiplexer 5. The multiplexer 5 is connected to a Bruel and Kjaer 2131 Digital Analyzer 6 and to an IBM 5110 Computing System 7 over an interface bus 8. A signal lead 9 interconnects the analyzer 6 and multiplexer 5 and a signal lead 10 interconnects the boom 1 and multiplexer 5 via a boom control box 11.

Output data may be displayed on the screen 12 of the analyzer 6 or may be printed by a printer 13 connected to the computing system 7. The article 14 under test is positioned in a hemi-anechoic room directly below the center of rotation of the boom.

In operation, a signal from the computing system 7 over bus 8 generates a signal via multiplexer 5 to trigger a timer in control box 11 which switches on the boom rotation motors for several seconds. Once the boom is moving, an internal synchronizing switch controls rotation of the boom for one revolution. The boom rotation time is adjusted to...