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Sound power estimation with an acoustic camera
2010 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Sound power describes a sound source regardless of its environment and is useful in noise control applications, but can be cumbersome and time consuming to measure. Sound power levels can rank different sound sources and is often restricted in noise control legislation. An acoustic camera records a sound field with a microphone array. Due to properties of the array, and by using beamforming algorithms, an acoustic camera can separate sound from different directions. The acoustic camera measures sound pressure from a sound source. By assuming directivity properties the sound power of a sound source can be derived from the sound pressure. In this thesis an acoustic camera has been evaluated in order to determine sound power estimation performance and sound source separation ability. This is tested by six different measurement set-ups in an anechoic chamber. Two different sound sources are used in the trials: one reference sound source and one disturbing sound source. The reference sound source has a calibrated and documented sound power level to which the measurement results are compared. Measurements were performed at 1 to 5 m distance from the acoustic camera with both sound sources. The influence of a disturbing sound source on the reference sound source sound power level was measured with the sound sources separated 0.65 m to 2.6 m. The measurements show that the sound power level could at best be determined within 1 dB. The acoustic camera can separate different sound sources well. Influence from a disturbing sound source, 10 dB SPL stronger and distanced 1 m from a reference sound source was 2 to 3 dB for mid-frequency one-third octave bands at 5 m measurement distance. Measuring sound power with an acoustic camera is fast and mobile compared to room interaction methods and sound intensity measurements. The results of this thesis are useful when measuring sound power levels, especially for sound sources such as chimney outlets, wind power stations and big objects that can not be moved or do not fit in a room.

Place, publisher, year, edition, pages
Keyword [en]
Social Behaviour Law, Acoustic camera, sound power level
Keyword [sv]
Samhälls-, beteendevetenskap, juridik
URN: urn:nbn:se:ltu:diva-46053ISRN: LTU-EX--10/011--SELocal ID: 3b232bb1-41c7-4f49-bdd2-fa50ef9a27aaOAI: diva2:1019362
Subject / course
Student thesis, at least 30 credits
Educational program
Media Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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