The thesis deals with the acquisition and usability of psychoacoustic characteristics of gear noise. In addition to the analyses of the influences of certain gear parameters on the psychoacoustic characteristics loudness, roughness, and sharpness, the prediction of the perceived annoyance using structure-borne sound is the main topic of this PhD thesis.
An introduction and an outline on prevailing research results on the topic of psychoacoustic analysis of gear noise are given in Chapter 1. Further, the aim of this study and first expec-tations on its results are defined. In Chapter 2, the basics of technical acoustics and psychoacoustics are explained, as far as necessary for the understanding of the study. Fundamentals of gear noise and means of vibrational monitoring and diagnostics already used to date are described. Based thereon the theoretical approach is explained. In Chapter 3, the design and construction of the test rig used for the acquisition of gear noise are thoroughly described. The test rig is validated and the test series is planned. It is shown that interference factors lower the quality of the technical acoustic analysis as well as of the psychoacoustic analysis when using airborne sound. Hence, the usage of structure-borne sound seems to be advisable. In Chapter 4, the standard state of the gear is evaluated and deviations caused by variations of rotational speed and torque as well as the exchange of gear wheels, i.e. production-state gear-wheels, damaged gear-wheels, and intentionally faulty-grinded gear-wheels, are analysed. Analysis shows that the change of psychoacoustic characteristics caused by damage is far less than expected. In Chapter 5, the feasibility of structure-borne sound in psychoacoustic analyses is examined in detail. Using scatterplots and correlation coefficients, the data of airborne and structure-borne sound are compared. In addition to the use of the raw acceleration signals, the use of a correction factor as well as a method to use the velocity signals to minimise systematic deviations caused by the usage of non-airborne sound in psychoacoustic analyses are discussed. The results are validated by a second test series using a gearbox excited by a shaker. Furthermore, the calculated perceived annoyance based on structure-borne sound is compared to previous hearing tests and shows high correlation. The PhD thesis concludes with Chapter 6, including a summary of the obtained results and an outlook on possible future developments, benefits, and areas of application of the developed methods. | English |