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Academic year
Didactic period
Primo Semestre

Training objectives

The course aims to provide knowledge of the basic principles of acoustics in its specific mechanical engineering applications.

The main knowledge acquired will be:

- basic notions about sound sources and sound perception
- knowledge of the quantities of interest in applied acoustics that are used in the design practice
- knowledge of the propagation of sound in the outdoor environment
- knowledge of typical acoustic problems in the indoor environment such as reverberation and sound level
- knowledge of sound insulation
- basic knowledge of the instrumentation for measuring the pressure and the sound intensity
- knowledge of sound absorption mechanisms and of sound absorbing materials
- knowledge of sound power measurement methods and their application
- knowledge of industrial noise sources
- knowledge of the methods of remediation of noise sources in the industrial sector

The main skills (i.e. the ability to apply the knowledge acquired) will be:

- predict the sound level propagated by external sources and the attenuation of acoustic barriers
- predict the sound level and reverberation time in the interior environment
- calculate the absorption coefficient of a porous material given its surface impedance
- calculate the resonance frequencies of homogeneous walls and predict their coincidence
- predict the acoustic insulation of thin homogeneous walls
- calculate the sound power from pressure or sound intensity measurements
- calculate the effectiveness of an enclosure for noise control
- size a silencer


It is necessary to have acquired and assimilated the following knowledge provided by the "Mathematical Analysis" and "General Physics" courses:

- elementary concepts of mathematical analysis, differential calculus and complex numbering;
- knowledge of the fundamental concepts of physics

Course programme

The nature of sound, the acosutic waves and the quantities that characterize them. Anatomy and physiology of the ear-5 hours
Sound propagation outdoors-3 hours
Insulation and sound absorption. Phenomena of absorption, reflection and transmission . The airborne sound insulation : the law of mass , resonance effect and coincidence, light walls , double walls , composite walls-8 hours
Sound absorption, sound-absorbing materials-2 hours
Propagation of sound in enclosed spaces
Acoustics of enclosed spaces : geometric treatment , treatment efficiency and statistics , the theory of Sabine . Sound energy density in the system , the reverberation time . Other expressions of the reverberation time . Reverberant acoustic fields and semi- reverberant . Acoustic field in an industrial environment-4 hours
Instrumentation and measurement techniques
Measured and frequency analysis : microphones, time constants , filters, equivalent level . Principles of signal analysis , FFT . Sound intensity , sound power , sound intensity measurement instrumentation , practical applications. Measurement of sound power: legislative and regulatory references for the sound power , sound power measurement with measurement of sound pressure level ( ISO 3740-3747 series ) with technical and sound intensity (ISO 9614-1/2 )- 8 hours
Reclamation of noise sources
Mode noise generation , encapsulation , silencers ( reactive , dissipative , mixed) , acoustic screens , environmental treatments-4 hours
Numerical exercises - 10 hours
Laboratory experiences - 4 hours

Didactic methods

For the A.Y. 2022/23 the lessons will be in presence. A remote consulting will be granted by streaming and also videorecorderd lessons will be made available.

Learning assessment procedures

First a written test after which you will be able to sustain the oral examination.
The written test is designed to assess the student's ability to solve numerically a simple issue of Applied Acoustics; during the oral examination will occur the theoretical and practical knowledge of Applied Acoustics.
The rating is assigned on a scale from 18 to 30/30 according to the answers given by the students on written test and theory questions.

Reference texts

Other recommended texts for study:
Manuale di Acustica Applicata, a cura di R. Spagnolo, Città Studi Edizioni, 2008;
L.Beranek, Noise and vibration control, Institute of Noise Control Engineering (1988).