Acoustics II

Learning Outcomes

Disciplinary Specific Learning Outcomes

Having successfully completed this module you will be able to:

• Explain the relationship between the wave equation and the Helmholtz equation, verify the equivalence of the two approaches when solving acoustical problems, and choose which one is appropriate in a given situation.
• Account, qualitatively, for the mechanisms of energy loss when sound is absorbed and distinguish between locally reacting and non-locally reacting boundaries.
• Discuss the continuity and momentum equations of fluid dynamics and use them to derive the acoustic wave equation in three dimensions.
• Calculate the transmitted and reflected waves when plane waves are obliquely incident on a plane interface between two fluids.
• Calculate the sound-field of monopole and dipole sources and source distributions, illustrate them by means of computer programs, and recognise their relationship to practical sources.
• Define and calculate sound energy and sound intensity.
• Explain the basic measurements made when assessing room acoustics and relate them to the acoustical theory previously developed and the description of absorption.
• Use the Helmholtz equation to obtain the modes of an acoustical space and explain how they can be used to obtain solutions to source radiation problems in that space.

1. Revision of basic principles of 1D sound propagation from Part I.

2. Conservation equations of compressible fluid dynamics for 3D sound fields.

3. The Helmholtz equation and the Wave equation in three dimensions.

4. Sound energy, sound power and sound intensity.

5. Sources of sound: monopoles, dipoles, vibrating surfaces.

6. Acoustic modes in ducts, enclosure and other systems.

7. Transmission and reflection of plane waves obliquely incident on a plane boundary.

Labs:

1. Impedance tube measurement.

2. Sound power measurement and relevant standards (engineering methods of sound power determination in a reverberation room, ISO9614-1 and ISO 9614-2; the precision method of sound power determination in an anechoic or semi-anechoic chamber, ISO 3745)

3. Vibroacoustics.

This is a one-semester course, two lectures and one tutorial per week with three laboratory sessions.

Lecture notes and tutorial sheets are provided and one-to-one assistance and verbal feedback is facilitated through twelve tutorial classes. Past exam papers are supplied to aid personal study, feedback and revision. Blackboard is used to allow the lectures and additional material to be disseminated (including solutions to past exam papers). The students have to write-up one laboratory report and one assignment report. Students are encouraged to read supporting texts and a booklist is provided.

The practical sessions will be held in teaching laboratory 13/4061 using a multiplicity of existing bespoke rigs and standard vibration measuring equipment. About 10 students can be accommodated per laboratory session.

Summative

This is how we’ll formally assess what you have learned in this module.

Referral

This is how we’ll assess you if you don’t meet the criteria to pass this module.

Repeat

An internal repeat is where you take all of your modules again, including any you passed. An external repeat is where you only re-take the modules you failed.