Overflying measurements using microphone arrays: an investigation of algorithms for sound source localization of complex moving objects
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Sound and vibration (MPSOV), MSc
Publicerad
2022
Författare
Fehratovic, Enes
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
It is common to find airports in the vicinity of greater cities where aircraft causes
health inflicting noise pollution. Deutsches Zentrum für Luft und Raumfahrt (German
Aerospace Center) have been a contributor in reducing sound emissions from
aircraft by proposing design changes backed by their research and experiments. To
be able to evaluate various design attempts in a real life scenario, sound sources
must be localized and quantified in an overflying measurement. At their private
airfield they conduct experiments using a microphone phased array. With post processing
techniques and the deconvolution algorithm, DAMAS, they have managed
to localize and quantify sound sources of aircraft.
DAMAS has been used by the German Aerospace Center since 2006. In recent
time they have been eager to investigate more novel algorithms for sound source
localization, and one in particular, called CLEANT. The goal of this thesis is to investigate
how CLEANT works and implement it in python code in order to evaluate
the results. This would be among the first attempts to use CLEANT on overflying
measurements at this scale. Both CLEANT and DAMAS requires beamforming to
be performed in order to enable further deconvolution of the results. The implementation
of CLEANT was successful and interesting results were obtained. The main
advantage of CLEANT is that it operates exclusively in the time domain whereas
DAMAS is a frequency domain algorithm. This means that CLEANT can take
the movement of the object into account whereas frequency domain algorithms are
better suited for stationary sources. Although CLEANT can cause a masking effect
leading to undetected sources who are very close to each other, CLEANT can operate
in lower frequencies than DAMAS. It also scales better for greater amount of
focus points in the grid, meaning that for higher resolution or larger area of analysis,
CLEANT is faster.
Beskrivning
Ämne/nyckelord
sound source localization, aircraft, beamforming, deconvolution, microphone array