Acoustical Measurements Using a Virtual Microphone Technique

Document type: Conference Papers
Peer reviewed: Yes
Author(s): Mathias Winberg, Henrik Åkesson, Thomas L Lagö, Ingvar Claesson
Title: Acoustical Measurements Using a Virtual Microphone Technique
Conference name: Internoise
Year: 2008
City: Shanghai, China
Organization: Blekinge Institute of Technology
Department: School of Engineering - Dept. of Signal Processing (Sektionen för teknik – avd. för signalbehandling)
School of Engineering S- 372 25 Ronneby
+46 455 38 50 00
http://www.tek.bth.se/
Authors e-mail: mathias.winberg@bth.se
Language: English
Abstract: Virtual sensing is the art of measuring a quantity at a certain spatial position without having a physical sensor placed at that exact same position. In practical applications, this technique is sometimes very useful, when it is not feasible to put the sensor at the position where the physical quantity should be measured. For example, a virtual microphone could be considered in the following scenario: The sound level, preliminary school environment, should be studied at the different students head positions. In order to get statistical relevant data, the measurement has to be carried out over a period of time. However, it is not a feasible approach to use a large number of microphones hanging from the ceiling at the students head level, over a longer period of time for obvious reasons. One thoughtful solution in such a situation is to put microphones at the walls and close to the ceiling and using the virtual technique to calculate the noise level at the students head positions based on the measure data. An advantage in such large setup is that it often requires less physical sensors than the number of virtual measurement positions and at the same time features a better validation and sanity check of the data.
The most popular application area, though, are active noise control (ANC) or active structural acoustic control (ASAC), where the aim is to move the zone of quietness away from the physical error microphones to the desired location of maximum attenuation.
This paper presents a virtual microphone concept for a sound measurement in a closed cavity.
Subject: Signal Processing\General
Signal Processing\Beamforming
Keywords: Virtual Microphone
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