The measurement of machinery sound power level (SWL) with optical cameras : theory and experimental validation

Baldini, Sofia (author), Deckers, Elke (author), Denayer, Hervè (author), Dong, Luyao (author), Gardonio, Paolo (author), Gorjup, Domen (author), Panagiotopoulos, Dionysios (author), Rinaldo, Roberto (author), Slavič, Janko (author)

The measurement of structural borne noise from vibrating sources relies on long-lasting laser vibrometry measurements or complex acoustic measurements carried out either in-situ with sound intensity or acoustic camera probes or in specially dedicated acoustic rooms. This research introduces an additional approach for reconstructing structure-borne sound radiation from optical camera multi-view recordings. The total sound power radiation is obtained by integrating numerically the acoustic sound intensity either on a far-field surface enclosing the radiator or a near-field surface given by the surface of the radiator itself. The sound intensity is derived from the flexural vibration reconstructed with frequency-domain triangulation from 16 sequential camera views and the radiation impedances calculated with a BEM model assuming free-field sound radiation. The near-field approach results into a compact matrix formulation, which can be suitably used to derive the radiation modes of the body. The Introduced method is applied to a model prism box and is validated against ISO 3744:2026 acoustic measurements taken in a semi-anechoic room. The method shows good agreement of both the narrow-band and third octave band sound radiation spectra reconstructed from the camera measurements and from the acoustic measurements, with deviations comprised between 0 and 2 dB in the third octave bands comprised between 250 and 1600 centre frequencies. The proposed method provides an additional in situ approach for reconstructing the sound radiation of optically accessible structures from short-duration full-field video acquisitions, which minimises measurement variability, enables detailed modal reconstruction of the structure sound radiation, and serves as acoustic design tool.

• Language: English
• Keywords: sound radiation measurement, vibration measurement, third-octave band SWL, narrow band Sound power level, photogrammetry, multi-view, frequency triangulation
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Publication date: 01.01.2026
• Year: 2026
• Number of pages: 14 str.
• Numbering: Vol. 290, part. D, art. 123051
• PID: 20.500.12556/RUL-186947
• UDC: 534.6
• ISSN on article: 1873-412X
• DOI: 10.1016/j.measurement.2026.123051
• COBISS.SI-ID: 290245635
• Publication date in RUL: 07.09.2026

Record is a part of a journal

• Title: Measurement
• Publisher: Elsevier
• ISSN: 1873-412X
• COBISS.SI-ID: 23272709

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: meritev zvočnega sevanja, meritev vibracij, terčni nivo zvočne moči, ozkopasovni nivo zvočne moči, fotogrametrija, večpogledovno, frekvenčna triangulacija

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P2-0263
• Name: Mehanika v tehniki

• Funder: EC - European Commission
• Project number: 101073014
• Name: Global Acoustic interaction and Psychoacoustic impact of the autonomous vehicles in interior and exterior NOISE
• Acronym: GAP_Noise