APPLIED ACOUSTICS
Academic year and teacher
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- Versione italiana
- Academic year
- 2022/2023
- Teacher
- NICOLA PRODI
- Credits
- 6
- Didactic period
- Primo Semestre
- SSD
- ING-IND/11
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 Prerequisites
- 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).
