Machine Acoustics



Julius Müller

Organisation MAK




The lecture "Machine Acoustics and Dynamic Causes" is offered as an elective course for students in the master's program. In this one-semester course will be studied the question of why vibrations can occur in mechanical engineering systems and under which circumstances they are audible to humans. The focus sits on the fundamental correlations of machine acoustics, but today's controversial phenomena such as infrasound are also considered. This includes, in particular, the excitation or excitability of a system as well as the transmission and radiation of sound energy. Examples from general mechanical engineering, rail vehicle technology and wind energy are used to discuss relevant problems in the acoustic environment and to promote an understanding of the overall acoustic system. Finally, the consideration of possibilities for noise reduction aims at deepening the contents of the preceding lectures by means of a practical example.



  • each summer semester V2/Ü2, SWS 4/ECTS credits 6


  • Seminar room at the CWD, Campus-Boulevard 61 (ground floor)



The lecture is given by:

Professor Ralf Schelenz

The exercise is given by:

Reza Golafshan

Exam Info

  • Oral examination by appointment
  • More detailed information in RWTHmoodle

Lecture Topics

Basic concepts of technical acoustics

  • Sound values, levels
  • Evaluation of sound
  • Calculating using level values
  • Individual perception of sound: psychoacoustics
  • Estimation methods for natural frequencies
  • Considerations both in the time and frequency domains, FFT
  • The chain of acoustic transmission in machinery


  • Types of excitation
  • Interlocking excitations
  • Analysis of the vibration behavior in a drivetrain
  • Basics of simulating torsional oscillation / multi-body simulation

Structure-borne noise

  • Estimation methods for the structure-borne noise level
  • Measuring structure-borne noise / damping structure-borne noise
  • Transmission paths
  • Modeling structure-borne noise behavior, FEM / SEA
  • Validation, experimental modal analysis

Emission / airborne sound

  • Emission behavior of simple structures
  • Modeling emission behavior, BEM / SEA
  • Measuring sound intensity
  • Metrological sound isolation

System analysis

  • Fundamental opportunities for noise reduction
  • Practical examples of acoustic optimization