Inlämning av Examensarbete / Submission of Thesis

Carlos Hernandez Matas and Diana Gomez Olmedilla BEE08:02, pp. 48. TEK/avd. för signalbehandling, 2008.

The work

Författare / Author: Carlos Hernandez Matas and Diana Gomez Olmedilla
Titel / Title: Image Theory Applied to virtual Microphones
Abstrakt 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 areas for virtual microphones are in 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. However, there is an important difference between virtual sensing for active
control and virtual sensing for a pure measurement situation concerning the delays introduced
by virtual sensing technique.
This specific thesis work deals with the calculus of all the possible paths and reflections
followed by a sound wave between the source and a given destination point, by using virtual
transducers in an enclosed environment where reverberation exists. The aim of this work is to
determine how to calculate that impulse response in a rectangular room in which the walls have
uniform reflection coefficients and there isn’t any kind of furniture inside. Besides, this project
specifies a simple way to make this calculus taking into account several sources and
destinations.

Ämnesord / Subject: Signalbehandling - Signal Processing
Elektroteknik - Electrotechnology
Nyckelord / Keywords: acoustics, image theory, geometry, reverberation

Publication info

Dokument id / Document id:
Program:/ Programme Dataingenjör/Computer Engineer
Registreringsdatum / Date of registration: 06/10/2008
Uppsatstyp / Type of thesis: C-Uppsats

Context

Handledare / Supervisor: Dr. Mathias Winberg
mwn@bth.se
Examinator / Examiner: Dr. Mathias Winberg
Organisation / Organisation: Blekinge Institute of Technology
Institution / School: TEK/avd. för signalbehandling
S-372 25 Ronneby
+46 455 38 50 00
I samarbete med / In co-operation with: Virtual Microphone Grupp

Files & Access

Bifogad uppsats fil(er) / Files attached: image theory applied to virtual microphones.pdf (955 kB, öppnas i nytt fönster)