Influence of loudspeaker directivity and measurement geometry on direct acoustic levels over façades for acoustic insulation tests with the International Standard ISO 140-5

Sánchez Bote, José Luis and Pedrero González, Antonio and Gómez Alfageme, Juan José (2012). Influence of loudspeaker directivity and measurement geometry on direct acoustic levels over façades for acoustic insulation tests with the International Standard ISO 140-5. "Applied Acoustics", v. 73 (n. 4); pp. 440-453. ISSN 0003-682X. https://doi.org/10.1016/j.apacoust.2011.11.003.

Description

Title: Influence of loudspeaker directivity and measurement geometry on direct acoustic levels over façades for acoustic insulation tests with the International Standard ISO 140-5
Author/s:
  • Sánchez Bote, José Luis
  • Pedrero González, Antonio
  • Gómez Alfageme, Juan José
Item Type: Article
Título de Revista/Publicación: Applied Acoustics
Date: April 2012
ISSN: 0003-682X
Volume: 73
Subjects:
Freetext Keywords: ISO 140-5; Sound insulation; Façade; Loudspeaker directivity; Coverage requirements
Faculty: E.U.I.T. Telecomunicación (UPM)
Department: Ingeniería Audiovisual y Comunicaciones [hasta 2014]
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

The International Standard ISO 140-5 on field measurements of airborne sound insulation of façades establishes that the directivity of the measurement loudspeaker should be such that the variation in the local direct sound pressure level (ΔSPL) on the sample is ΔSPL < 5 dB (or ΔSPL < 10 dB for large façades). This condition is usually not very easy to accomplish nor is it easy to verify whether the loudspeaker produces such a uniform level. Direct sound pressure levels on the ISO standard façade essentially depend on the distance and directivity of the loudspeaker used. This paper presents a comprehensive analysis of the test geometry for measuring sound insulation and explains how the loudspeaker directivity, combined with distance, affects the acoustic level distribution on the façade. The first sections of the paper are focused on analysing the measurement geometry and its influence on the direct acoustic level variations on the façade. The most favourable and least favourable positions to minimise these direct acoustic level differences are found, and the angles covered by the façade in the reference system of the loudspeaker are also determined. Then, the maximum dimensions of the façade that meet the conditions of the ISO 140-5 standard are obtained for the ideal omnidirectional sound source and the piston radiating in an infinite baffle, which is chosen as the typical radiation pattern for loudspeakers. Finally, a complete study of the behaviour of different loudspeaker radiation models (such as those usually utilised in the ISO 140-5 measurements) is performed, comparing their radiation maps on the façade for searching their maximum dimensions and the most appropriate radiation configurations.

More information

Item ID: 22679
DC Identifier: http://oa.upm.es/22679/
OAI Identifier: oai:oa.upm.es:22679
DOI: 10.1016/j.apacoust.2011.11.003
Official URL: http://www.sciencedirect.com/science/article/pii/S0003682X11002982
Deposited by: Memoria Investigacion
Deposited on: 25 Mar 2014 15:34
Last Modified: 21 Apr 2016 17:40
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