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Untersuchung der Klangcharakteristik von Fahrzeugen mit Motoren kleiner Zylinderzahlen

Authors Ulz, A.
Year 2014
Thesis Type Master's thesis
Topic Audio Signal Processing
Abstract Downsizing of combustion engines by reduction of the number of cylinders leads to unusual acoustical perceptions and customer complaints. The aim of this master thesis is to evaluate the sound character of cars with engines with low cylinder numbers and to describe the differences between different cylinder numbers using objective valuation methods. The investigations are carried out on a data base of interior noise recordings of full load run ups in 2nd gear on a test track for cars with 3 and 4 cylinder Diesel and Otto engines. Various acoustic and psychoacoustic parameters are investigated by methods of statistics. Using three psychoacoustic parameters an index for the evaluation of acoustic comfort in the passenger compartment is developed which allows a statistical distinction of groups of cars with 3 and 4 cylinder engines and also an assessment within the engine groups. Furthermore, proven theories about harmonic analysis and timbre are used to describe intervallic structures of engine order spectra and to evaluate the timbre characteristics for different cylinder numbers. Evaluations of amplitude proportions between engine orders lead to additional possibilities to characterize and distinct the interior noise of cars with 3 and 4 cylinder engines. The presented valuation methods show different potentials to characterize the interior noise of cars with low cylinder numbers and to distinct cars with 3 and 4 cylinder engines. Moreover, the physical meaning of the gained knowledge is discussed and an overview of the practicability is given.
Supervisors Sontacchi, A.