Course detail

# Vibration, Noise and Bioacoustics

Vibrations and noise are a general accompaniment to all machinery operations. The whole chain encompassing the vibration sources, transfer paths of the structure, noise emitters on the machine surface and ambient acoustic environment needs to be analyzed. Bioacoustics is dealing with human organs and the organs of the other living creatures, whose function is connected to use of acoustic waves generally on using of acoustics. Bioacoustics is dealing especially with the human voice production and hearing perception.
Basic areas of examination:
Acoustic variables, wave equation and its solution, spectra of vibro-acoustic quantities, acoustic properties of open and closed spaces, mechanical and aerodynamical sound sources.
Experimental analysis of acoustic variables, identification of sources of vibrations and noise.
Passive and active methods of noise reduction.
Vibroacoustic systems of machines - deterministic models (finite element method FEM, boundary element method BEM), statistical models (statistical energy analysis SEA), hybrid models (FEM + SEA).
Biomechanics of the human voice and hearing.

Learning outcomes of the course unit

To analyze the noise of machines, to identify the sources of vibration and noise, modeling of dynamic phenomena in the working processes, implement active and passive methods of vibration and noise reduction. On base of machine noise analysis then propose appropriate design and other arrangements, so that the dynamic properties of machines will be influenced in the desired direction.

Prerequisites

Fundamentals of acoustics: acoustic wave, acoustic quantities (pressure, intensity, power), acoustic signal spectra, experimental analysis of the acoustic quantities, acoustic fields, spectral and modal properties of acoustic cavities. Mathematics: matrix algebra, linear algebra, differential equations, basics of finite element method.

Co-requisites

Not applicable.

Recommended optional programme components

Not applicable.

Nový, R.: Hluk a chvění, České vysoké učení technické, Praha, 2009 (CS)
Mišun, V.: Vibrace a hluk, Vysoké učení technické, Brno, 1998 (CS)
Rossin, T. D., editor: Springer Handbook of Acoustics, Springer, Würzburg, 2007 (EN)
Beranek, L.L.: Acoustics: Sound Fields and Transducers, Academic press, Oxford, 2012 (EN)
Ohayon, R., Soize, C.: Structural Acoustic and Vibration, Academic Press, London, 1998 (EN)
Titze, I. R., Alipour, F.: The Myoelastic Aerodynamic Theory of Phonation, National Center for Voice and Speech, Denver and Iowa City, 2006 (EN)
Beer, G., Smith, I., Duenser, Ch.: The Boundary Element Method with Proramming, Springer-Verlag, 2008 (EN)
Lyon, R. H., DeJong, R.G: Theory and Application of Statistical Energy Analysis, Butterwortth-Heinemann, Boston, 1995 (EN)

Planned learning activities and teaching methods

The course is taught through lectures explaining the basic principles and theory of the discipline. Exercises are focused on practical topics presented in lectures.

Assesment methods and criteria linked to learning outcomes

The classified accreditation is prescribed for the subject.
The claims for accreditation:
Accreditation is carried out by means of the written test at the term end. The test consists of ten questions covered the most important areas of the course. A correct answer to less than half of the questions is cause not to give the accreditation. At the end of the semester, each student must submit the required number of resolved dynamic problems.
Participation on the exercises is compulsory. Head of exercises carry out continuous check of student’s presence, their activity and fundamental knowledge. A not excused presence in the exercise is a reason not to give the accreditation.
Definite form of the fulfilment of these claims defines the head of exercises in the term begin.

Language of instruction

Czech

Work placements

Not applicable.

Course curriculum

1. Acoustic variables, linear and decibel representation
2. Spectra of acoustic variables : band pass, tracking,
multispectra
3.Acoustic properties of a closed areas
4.-5. Biomechanics of a human voice and hearing
6.Experimental identification of machine acoustic power
7.Aerodynamic noise sources, principles and examples
8.Passive methods of vibration and noise reduction
9.Principle of reactive dampers of pipe systems
10-11.Deterministic models of vibroacoustic machine systems:
- the coupling structure of vibroacoustic machine systems
- the methods of solution (FEM and BEM)
12-13. Statistical models of vibroacoustic systems (method SEA)

Aims

The aim of the course is practical and theoretical analysis of machine noise, computational modeling of their systems in order to reduce the vibration and radiated acoustic energy. Introduction to modern methods for the analysis and solution of vibrations and noise of machinery and specialized software systems for their solution. Further attention will be given to the biomechanics of human vocal tract and the human auditory organ. The function of both organs will be analyzed theoretically, by computer modeling using the finite element method and will be analyzed by the experiments.

Specification of controlled education, way of implementation and compensation for absences

Attendance at practical training is obligatory. The inspection of the education is carried out systematically, on the exercises the presence will be written in the student’s list. A student’s preparedness for the education is carried out continuously and individually in the students, or by the short test. In case of orderly excused missing presence it is necessary to fulfil the missing items and optionally to solve some compensatory examples. A missing experimental exercises it is necessary to compensate in the alternate time.

Classification of course in study plans

• Programme M2A-P Master's

branch M-IMB , 2. year of study, winter semester, 5 credits, compulsory-optional

#### Type of course unit

Lecture

26 hours, optionally

Teacher / Lecturer

Syllabus

1. Acoustic variables, wave equation and its solution
2. Linear and decibel representation, spectra of acoustic variables: band, tracking, multispectra
3. Acoustic properties of open and closed spaces
4. Mechanical and aerodynamical sound sources - principles and examples
5. Biomechanics of human voice production
6. Biomechanics of human voice – vocal folds and their functions
7. Biomechanics of a human hearing
8. Psychoacoustic noise criteria
9. Experimental identification of acoustic variables
10. Passive and active methods of vibration and noise reduction
11. Deterministic models of vibroacoustic systems: Finite element method (FEM)
12. Deterministic models of vibroacoustic systems: Boundary element method (BEM)
13. Statistical models of vibroacoustic systems (statistical energy analysis SEA), hybrid models (FEM + SEA)

Computer-assisted exercise

26 hours, compulsory

Teacher / Lecturer

Syllabus

1. Acoustic variables and their conversions, band spectra, decibel scales
2. Spectral and modal properties of cavities
3. Acoustic wave propagation in open space, acoustic sources
4. Vocal tract organ, spectral and modal properties
5. Vocal folds and their functions
6. Experimental analysis of voice, formants of vowels
7. Human ear: computer modeling
8. Noise source identification, acoustic emitters
9. Acoustic power emitted by the machine
10.-11. Modeling of vibroacoustic systems using FEM
12. Statistical models, modeling using the SEA
13. Credit