Learning objectives
Knowledge and understanding:
For students of all branches of engineering this is a key course, it is practically the only opportunity to see (or, rather, hear) the techniques learned in previous courses, in which the purely theoretical foundations of modern advanced mathematical methods are taught. When the "numbers" are transformed into sound, abstruse and difficult mathematical procedures (such as differentiation and integration) quickly become very clear and immediate, and the possibilities offered by sound editing systems on the PC, used extensively both during lectures and during laboratory exercises, make it possible to listen immediately (usually in real time) to the "effects" of filters or other devices (compressors, gates, convolvers, denoising, etc.).
Applying knowledge and understanding:
The course is tailored to practical application, not to theoretical knowledge. Great emphasis is given to measurement methods, simple computations performed in Excel, and solution of practical problems. The student will learn to use the decibel scale, to “think in decibels”, and to perform the common math operations on dB values.
Making judgments:
In the whole course the judgment method is always based on human listening experience, not on numerical evaluation of the results. Acoustics is a perceptual science, and the final judgement can only by given by our hearing system, and not by means of “objective” numerical quantities. The students are consequently trained to listen and evaluate perceptually the most relevant acoustical effects, such as frequency-domain filtering, reverberation, echo, noise contamination, etc.
Communication skills:
The goal of this course is not, definitely, to train the students to perform as actors on stage. However, a significant part of the course is devoted to the study of the verbal and musical communication between performers and audience. In this part of the course, the students learn some tricks employed by professional actors and musicians, and become skilled in diagnosis and correction of communication problems due to room acoustics, improper design of the electro acoustical systems, or improper use of them by the performers and the audience.
Prerequisites
None. But this is a “postgraduate” course, so it will be extremely difficult for students choosing it during their undergraduate program.
Course unit content
The course of Applied Acoustics is an introductory course to a scientific and technological field undergoing a very rapid development, which offers great employment opportunities, and which involves disciplines apparently very different: architecture, structural engineering, physiology, psychology, statistics, physics, electronics, vibration mechanics, fluid dynamics, digital signal processing, telecommunications, measurements, hygiene of the workplace, music, musicology, virtual reality.
Obviously in a course of 6 CFUs we can only provide the methodological basis of the topic, which must then be furthered in more in-depth courses, such as courses for Competent Technicians in Environmental Acoustics or Master Courses available at some Italian or foreign universities (for example Perugia , Naples , Florence , Rome), or even dedicated post-graduate degrees (these are usually abroad, but in Italy it must be evidenced the post-graduate (advanced) degree in Sound and Music Engineering of Politecnico di Milano, taught entirely in English, delivered at the Como Campus).
Because of its multidisciplinary and transversal nature, the Course of Applied Acoustics is attended by students from various degree programs (almost all branches of Engineering, but also some Architecture students, and even the students of the course in Techniques of Prevention in the Environment and at the Workplace of the Faculty of Medicine, for which attendance is compulsory only to the first part of the course, with the exclusion of the final part dedicated to electroacoustic and musical applications).
Full programme
Lesson 0 Course introduction, program, web page
Lesson 1 Nature of sound, fundamental physical quantities
Lesson 2 Energy & Sound, scale of decibels
Lesson 3 Human auditory system, loudness evaluation, weighting curves
Lesson 4 The Sound Level Meter, equivalent level, calibration, time history with different time constants (slow, fast, etc.)
Lesson 5 Sum and subtraction of values in dB, examples of dB summation, Spectral Analysis, FFT, octave bands, Bark bands
Lesson 6 Free Field sound propagation, point sources, spherical divergence, directivity
Lesson 7 Linear sources, cylindrical divergence, excess attenuation
Lesson 8 Noise screens, Maekawa formulas, examples
Lesson 9 Indoor sound propagation, semi-reverberant field, critical distance
Lesson 10 Reverberation time, definition and Sabine's formula
Lesson 11 Environmental correction factor K2, sound propagation inside not-Sabinian rooms.
Lesson 12 Digital sampling of sound, digital filters, FFT, convolution in time and frequency domain
Lesson 13 Measurement of impulse response: impulsive sources, microphones
Lesson 14 Measurement of impulse response: loudspeakers, MLS and ESS methods
Lesson 15 ISO3382 standard, acoustical parameters: T20, T30, EDT, Clarity, Definition, Center Time, IACC, Jlf, G
Lesson 16 Speech Transmission Index: measurement and calculation
Lesson 17 Sound absorbing materials, typical products. Example of measurement of Alpha Sabine according to ISO 354 (reverberant room)
Lesson 18 Sound insulating materials, typical products. Frequency dependence of the Sound Reduction Index R, the Mass law, resonances and coincidence.
Lesson 19 Italian law about building acoustics (DPCM 5/12/1997), experimental assessment of compliance
Lesson 20 Italian law about environmental noise (L. 447/1995), acoustical zoning, the new EC standards based on Lden - Results
Lesson 21 The Single Event Level (SEL) and its usage for evaluation of transportation noise
Lesson 22 Examples and exercises regarding environmental noise
Lesson 23 Examples and exercises regarding noise at the workplace
Lesson 24 Digital Sound Processing, FIR and IIR filters, FFT, aliasing, windows, spectrogram
Lesson 25 Fast convolution by FFT, partitioned convolution, computation of FIR coefficients for inverse filters, the Kirkeby inversion
Lesson 26 Measurement of the absorption coefficient: reverberant room, standing wave tube, sound intensity method, impulsive method
Lesson 27 The Hour of Code - writing small programs (plugins) for audio
Lesson 28 The Hour of Code - using visual programming for audio processing
Lesson 29 The Hour of Code - examples of coding
Lesson 30 Techniques employed for sound recording and reproduction, mono, stereo, multichannel, 3D, the Soundfield microphone, Ambisonics
Lesson 31 Wave Field Synthesis (WFS), loudspeaker arrays, the Casa del Suono lab in Parma
Lesson 32 Microphone arrays, virtual microphones, the RAI project
Lesson 33 Simulation of sound propagation outdoors employing the DISIA/CITYMAP software package
Lesson 34 Simulation of sound propagation indoors employing the RAMSETE software package
Lesson 35 Auralization of the results with the AURORA software package
Bibliography
The official textbook for the Applied Acoustics course is:
P. Fausti: Acustica in Edilizia , Rockwool Italy, Milan (2005) - in Italian - free download in PDF format, you can also request for a free hardcopy to Rockwool. Thanks Rockwool!
The books RECOMMENDED (not required) for thorough preparation of the exam are:
ACUSTICA
Fondamenti e applicazioni
Autori: R. Spagnolo
Marchio: UTET Università
Anno: 2015
ISBN: 9788860084460
Thomas D. Rossing (ed.): Springer Handbook of Acoustics, Springer
Science+Business Media, New York (2007)
Online Notes:
The support material for the course used during the lessons is available in the "Public" section of this website:
http://pcfarina.eng.unipr.it/Acoustics-2015-Lessons.htm - It is recommended to download especially Powerpoint slides and Excel spreadsheets containing the exercises done in the classroom.
Teaching methods
The "theory" of the lessons is administered by computer tools, avoiding traditional "lectures" in the classroom. The teacher posts on the website a variety of media (slides, handouts, videos of lectures), indicating to the students to which of them they should access before each "lesson" in the classroom.
During these lessons, the classroom activities will be of "workshop" type, with problem solving and execution of project sizing, partly carried out by the teacher as an "example", and then replicated by the students.
This type of activity also includes systematic verification of the progress gradually achieved, resulting in building an individual assessment profile for each student, and therefore with the possibility of establishing aids and supports for those who are falling behind.
Assessment methods and criteria
The assessment consists of two separate tests:
1) a written examination, consisting of a number of exercises to be solved in numerical form. The use of pocket calculator, notes, handouts, charts and graphs is allowed. Some students may be exempted from the written test, on the basis of the results obtained during in-class tests.
2) Oral examination, which focuses mainly on theoretical topics, and which can be accessed only after passing the written test. Again some students may be exempted from it, on the basis of in-class test results.
Other information
http://pcfarina.eng.unipr.it/Acoustics-2015.htm
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