Course syllabus

Akustik
Acoustics

VTAN01, 7,5 credits, A (Second Cycle)

Valid for: 2019/20
Decided by: PLED V
Date of Decision: 2019-04-01

General Information

Elective for: F4, V4-hb, V5-ko
Language of instruction: The course will be given in English

Aim

The purpose of the course in acoustics is to give knowledge of sound propagation in different media, namely in fluids such as air and in vibrating systems of solid structural elements, where different wave types (i.e. longitudinal waves, transversal waves and bending waves) together with their properties, are introduced.

Learning outcomes

Knowledge and understanding
For a passing grade the student must

• Be able to describe the physical foundations of waves in solid materials and describe wave propagation in infinite media and structural elements such as rods, beam and plates.
• Be able to interpret fundamental concepts such as acoustic effect, intensity and wave impedance.
• Be able to describe different mechanisms for damping and methods for experimental measurement of damping and have knowledge about how to change the damping properties of a structure.
• Be able to understand and use expressions for point impedance for infinite beams and plates.
• Be able to describe the causes for sound reflection and transmission at blocking elements and understand what happens at a periodic occurance of blocking elements.
• Be able to describe sound radiation from structures.
• Understand how sound is propagating in ventilation systems and explain how to attend to ventilation related noise problems.
• Be able to predict and measure noise from wind turbines.
• Be able to predict and measure sound reduction index in walls and structures.
• Be able to predict and measure simple sound invironments.
• Be able to properly design a room from an acoustic point of view.

Competences and skills
For a passing grade the student must

• Be able to calculate the eigenfrequencies, eigenmodes and mode density in finite systems with simple geometries and boundary conditions.
• Be able to analyse a given construction with regards to sound reflection and transmission.
• For a given structural element, be able to design a discontinuity in order to achieve a wanted reflection.
• Be able to calculate the sound radiation from a point-, line- and plane source.
• Easily use concepts introduced in the course, such as impedance, loss factor, radiation factor.
• Be able to present the solution of a given acoustic problem in a written technical report.

Judgement and approach
For a passing grade the student must

• Be able to critically evaluate different technical solutions, measurement methods and calculation methods and their applicability in different situations.

Contents

Different wave types and their respective properties. Longitudinal, transversal and bending waves. Wave propagation in beams and plates. Wave propagation, transmission and reflection in and between different meda. Damping mechanisms and the mathematical description. Plates with damping layers. The concept of impedance. Inimpedance in beams and plates. Transmission of structure bourne sound. Periodical structures. Noise in ventilation systems. Statistical Energy Analysis. Sound radiation from structures. Elementary sound radiators. Acoustics in volumes.

The course contains a larger project task where several of these aspects are included.

Laborations
The course contains three laborations á 4 hours where the content varies depending on the focus of the course during the given year. Example of laborations are:

• Introduction to sound propagation
• Impedance measurement
• Sound propagation in solid media
• Reverberation time and eigenmodes in room acoustics
• Sound transmission
• Step sound isolation
• Measurement of noise from wind turbines
  
  

Project tasks
The course contain a project task that is aimed at a topic according to the given foces of the course, such as:

• Modelling of oscillation in beams and plates
• Modelling of flanking and direct transmission
• Measurement and evaluation of noise from wind turbines
• Free topic

Examination details

Grading scale: TH - (U,3,4,5) - (Fail, Three, Four, Five)
Assessment: Passed written exam, passed project task and passed laboration reports.

The examiner, in consultation with Disability Support Services, may deviate from the regular form of examination in order to provide a permanently disabled student with a form of examination equivalent to that of a student without a disability.

Admission

Admission requirements:

• FMAA05 Calculus in One Variable
• FMA430 Calculus in Several Variables or FMAB30 Calculus in Several Variables

Required prior knowledge: VTAF01 Sound in Building and Environment
The number of participants is limited to: No
The course overlaps following course/s: VTA016, VTA060, VTAF05

Reading list

• Delphine Bard and Juan Negreira: Acoustics in Practice. 2016.
• Extra material handed out by the department.
• Lecture notes, instructions for project tasks and laborations.

Contact and other information

Course coordinator: Delphine Bard, delphine.bard@construction.lth.se
Teacher: Juan Negreira, Juan.Negreira@construction.lth.se
Course homepage: http://www.akustik.lth.se