APPLIED ACOUSTICS
cod. 1005233

Academic year 2020/21
2° year of course - First semester
Professor
FARINA Angelo
Academic discipline
Fisica tecnica ambientale (ING-IND/11)
Field
A scelta dello studente
Type of training activity
Student's choice
48 hours
of face-to-face activities
6 credits
hub: PARMA
course unit
in ENGLISH

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

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.

Because of its multidisciplinary nature, the Course of Applied Acoustics is attended by students from various degree programs (almost all branches of Engineering, but also some Architecture students).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.

Full programme

Physical Acoustics:
Definition of quantities. Propagation of mechanical disturbances in an elastic medium.
Sound pressure and particle velocity. The speed of sound.
The wave equation.
Sound intensity and sound energy density. Active and reactive intensity. Propagating and stationary sound fields.

Psychoacoustics:
Physiological and psychological mechanisms of sound perception by humans.
The logarithmic scale of decibels (dB), elementary operations on quantities expressed in dB. Frequency weighting curves.
Masking phenomena in time and in frequency. Audio compression algorithms based on psychoacoustic principles.

Sound Propagation:
Plane waves, spherical waves, standing waves. Sound reflection and absorption.
Sound propagation outdoor.
Room acoustics: reverberation, sound quality in concert halls and opera houses, ISO3382 acoustical parameters.
Advanced methods for impulse response measurement.

Digital Signal Processing applied to audio and acoustics.
Fundamentals of spectral analysis and Fourier transform.
Sampling of signals.
The DFT and the FFT algorithms. Convolution.
FIR and IIR filters, calculation of Inverse numerical filters.
Active control of sound.
Auralisation.
Virtual acoustics and 3D audio.

Electroacoustics and instrumentation for acoustic measurements:
Acoustic transducers (microphones, loudspeakers).
Devices for processing analog and digital acoustic signals: amplifiers, equalizers, reverbs, compressors, etc...
Sound level meters, spectrum analysers, impulse response measurement systems.
Virtual Instrumentation on PC and software for acoustical measurements, with practical experiments.

Techniques for numerical simulation of sound propagation:
Fundamental of finite element methods, boundary element methods, and ray tracing.

Bibliography

The recommended textbooks for an introduction to this topic are:

P. Fausti: Acustica in Edilizia , Rockwool, Italy, Milan, 2005 (free download in PDF format)
In Italian

R. Spagnolo: Acustica: Fondamenti e applicazioni, UTET Università, 2015, ISBN: 9788860084460

T. D. Rossing (ed.): Springer Handbook of Acoustics, Springer Science+Business Media, New York, 2014
https://www.springer.com/it/book/9781493907540
ISBN 978-1-4939-0754-0

L.E. Kinsler, A.R. Frey, A.B. Coppens, and J.V. Sanders: Fundamentals of Acoustics, Wiley & Sons, 2000

F. Fahy: Foundations of Engineering Acoustics, Academic Press, 2000,
ISBN: 9780122476655

Teaching methods

The course includes a combination of frontal lectures and workshop/laboratories.
The theoretical background of the material covered by this module will be explained during frontal lectures. Computer-based and practical demonstrations will often be used during lectures to demonstrate the practical aspects of this discipline.
Hands-on workshop or laboratories, with the aid of computers or measurement equipment, will also be carried out to allow students to familiarise themselves with numerical simulations and signal processing and with experimental measurements.
Class tests will be carried as formative or summative assessment to monitor and evaluate student progress.
If the normal activity in classroom will be impeded by the COVID-19, frontal lessons will ne replaced with pre-recorded and freely downloadable video recordings, while workshops and intermediate tests will be performed by means of interactive meetings on MS Teams.
In no case a "blended" didactic approach will be employed, with some students in the classroom, and synchronous streaming of the lesson. This approach is not effective and technically bad.
So there are just two possible cases: normal lessons in presence in the classroom for all students (preferable), or instead all at home with remote learning.

Assessment methods and criteria

The assessment consists of two separate tests:
1) a written examination, consisting of a number of exercises. 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.

Other information

Elly sucks, so I will employ my personal web site for the support of this course.

This is the official web page for the Applied Acoustics 2020 course: http://www.angelofarina.it/Acoustics-2020.htm

And this is the web page containing the calendar of the lessons. For each lesson students can download the Powerpoint slides, the lesson notes taken by students of previous years, and a video-audio recording of each lesson:

http://www.angelofarina.it/Acoustics-2020-Lessons.htm

Students not following the lessons in the classroom should use MS Teams as the platform for remote learning for this course.
This is the link to the Applied Acoustics Team: https://teams.microsoft.com/l/team/19%3a49459f41738f483aa17d1b9eef54091e%40thread.tacv2/conversations?groupId=e5b08a42-3128-438a-b6fa-8dc29498dda0&tenantId=bb064bc5-b7a8-41ec-babe-d7beb3faeb1c

Here the code for subscribing to the Team without need of requesting access to the teacher: nhhw618
NO "hybrid" lessons will be done, with some students in the real classroom and some others at home, watching in streaming.