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Introduction: Motivation, environmental pollution noise, human hearing, harmfulness limits, guidelines, noise assessment (emission and immission limits), noise types.
Level calculation: motivation and definition of levels, reference values, level arithmetic, rating levels.
Introduction to machine acoustics: vibrations, single-mass oscillator, impedance and admittance, wave equation of the sound field, solution of the wave equation for 1D-, 2D- and 3D-sound fields, types of radiators and laws of propagation (spherical radiator – line radiator – area radiator), reflection and absorption, interference, diffraction, relationship between displacement, vibration velocity, and acceleration.
Signal processing: frequency analysis, frequency filter, third octave and octave filters, A-, C- and Z-weighting.
Machine Acoustic measurement techniques: transducers, methods of sound power determination: free field method, reverberation field method, reference sound source method, sound intensity method.
Fundamental equation of Machine Acoustics and engineering noise control: noise generation in force-excited and velocity-excited machine structures, direct and indirect sound generation, distinction between primary and secondary noise reduction. |
