Applied Acoustics course (6 CFU) - Progressive list of lessons

Also in academic year 2015/2016 this course is taught in English
Click Here for accessing the Italian version of this page

Students of Techniques of Prevention, Click Here for instructions

Post-Graduate (Advanced) Degrees: Telecommunication Engineering, Electronics Engineering, Computer Engineering, Mechanical Engineering, Civil Engineering, Environment and Land Engineering, Physics

Teaching Hours:    Friday, 14.30 - 18.30

Beginning of the course: 02 October 2015

Lecturer: prof. Angelo Farina

E-MAIL: farina@unipr.it

Website: http://pcfarina.eng.unipr.it/ or http://www.angelofarina.it/

Receiving hours: Friday, 10:30 to 12:30 - building 7 (not recommended - better to use email).

WARNING !!! Between 29/02/2016 and 10/06/2016 the receiving period is temporarily modified to:

Thursday, 10.30 to 12.30

Phone Number: 0521-905854 (not recommended)

Contents
 

Introduction

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 further studied in more advanced courses, such as courses for Competent Technicians in Environmental Acoustics or Master Courses available at some Italian 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).

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 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.).

Given the scientific interests of the teacher, the course covers both the noise-related topics common to all branches of engineering and hygienistics (also as a consequence of the extensive legislative framework on buildings, environment and workplace), and the more specific themes relative to the acoustics of theatres and cinemas, audio production in music and television / film, musical instruments, high fidelity recording and Stereo (1D), Surround (2D) and three-dimensional (3D) playback systems.

The topics are always presented with systematic help of test sounds, as this is the most direct way to make the various operations to be perceived.

EXAMPLE:

Many students do not understand the physical meaning of "differentiation" and "integration" operators applied to a function. Math teachers tend to give "graphical" explanations , such as "the derivative is the slope of a curve" or "the integral is the area under a curve." These explanations are useless for those who are devoid of the capacity of visualisation needed to transform these concepts into images.

In acoustics, the operations of differentiation or integration modify the spectrum of a sound. In particular, differentiation boosts high frequencies (increases the sound level of 6dB/octave). On the contrary, integration boosts low frequencies. Here's an example, which allows to "listen" to differentiation and integration applied to a recording of the human voice:

Original.mp3

Differentiated.mp3

Integrated.mp3

A more extended presentation of this topic is developed in this web page

Program of the Applied Acoustics course  

  • Physical Acoustics: definition of quantities, propagation of mechanical disturbances in an elastic medium, sound pressure, particle velocity, speed of the sound wave. Equation of the acoustic waves.
  • Energetical Acoustics: sound propagation seen as energy transport. Definition of Sound Intensity and Sound Energy Density. Active and Reactive energy, propagating and stationary sound fields. The Reactivity Ratio (or index).
  • 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, methods of Loudness assessment, frequency analysis with constant bandwidth, with constant percentage bandwidth (octaves, etc.), with critical bands (Bark). Masking phenomena in time and in frequency. Use of psychoacoustics for encoding "lossy" and "lossless" audio signals with large reduction of the "bitrate" required (MP3, WMA, AAC, FLAC, OGG, etc.).
  • Sound Propagation: plane waves, spherical waves, standing waves. Reflection and absorption. Specular and diffuse reflection . Definition of sound absorption coeff. and scattering coeff. . Measurement techniques of the absorption coeff. and of the scattering coeff. .
  • Propagation outdoors: ground absorption, effect of temperature and wind gradients, of air absorption, of shielding or obstacles. The Maekawa and Kurze-Anderson formulas for the estimation of shielding attenuation.
  • Propagation indoors: the phenomenon of multiple reflections, stationary reverberant field. Formulas of the reverberant field and of the semi-reverberant field. Transients when a sound source is switched on and off: sound tail, impulse response of a room, Schroeder backward integration. Definition of Reverberation Time T60 and other quantities related to the acoustic transients. Sabine formula for the estimation of the reverberation time. The apparent sound absorption coefficient, and its measurement by tests in reverberation room.
  • Propagation through building structures: insulation of partitions, windows, tapping noise. Measurement techniques and Italian law.
  • Digital Signal Processing applied to audio and acoustics. Sampling sound, artefacts due to limited amplitude resolution and temporal discretization. Basic algorithms for digital filtering (FIR, IIR): a complex theory made easy. The FFT algorithm, fast convolution, partitioned convolution. Effects of nonlinearities and of time variance.
  • Advanced method for impulse response measurement (MLS, ESS, etc.). Sound quality in concert halls and opera houses. ISO3382 acoustical parameters. Temporal and spatial parameters. Use of directive microphones for assessing the spatial properties of the sound field inside a room.
  • Speech intelligibility in classrooms, auditoria and over telecommunication systems. The signal-to-noise ratio, effect of reflections and reverb. The Speech Transmission Index (STI) and its measurement.
  • Electroacoustics: transducers (microphones, loudspeakers). Devices for processing analog and digital acoustic signal: amplifiers, equalizers, reverbs, compressors, etc... Applications in the audio/electronics industry, in the field of telecommunications and broadcasting, in the recording industry and in entertainment industry automotive, in aviation and marine sectors.
  • Techniques for numerical simulation of sound propagation: finite element models, boundary elements, ray tracing, beam tracing. Using simulation programs, with hands-on practice in the laboratory. 
  • Instrumentation and equipment for acoustical measurements: sound level meter, spectrum analyzer, impulse response measurement system. Virtual Instrumentation on PC, software for acoustical measurements, with practical exercises in the laboratory.
  • Numerical processing of the acoustic signal: from general theory to practical applications on PCs. Auralization, virtual acoustics reality. Outline of modern applications in the entertainment industry, and future uses for "live" real time applications. "Plugins" for digital processing of acoustic effects; FIR and IIR filters, fast convolution, calculation of Inverse numerical filters, active cancellation of sound.
  • The 4 modern methods for measuring absorption coefficients: ISO 354 (reverberation room), ISO 10534 (standing wave tube), the Intensimetric Method (Farina/Torelli), the Impulsive Method (EN 1793/5).
  • The Hour of Code: programming in traditional languages (Javascript, Visual Basic) and in a modern graphical environment (Plogue Bidule).
  • Measurement of impulse response and other major acoustic parameters employing Aurora, numerical simulation of the sound field inside a room and outdoors by making use of two calculation programs (Ramsete, Disia).

 

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"Flipped Classroom" Didactical Approach

In academic year 2014/2015 a  "Flipped Classroom" method was adopted for the first time. It was an experimental application of this method, and during the current academic year some variations will be introduced.

The "flipped classroom" method is based on homework done IN ADVANCE, prior of each "lesson" in the classroom - but there will be no lesson, actually! The in-class activity is made mostly of experiments, tutorials, exercises, and a final on-line test, which has principally didactical purposes, albeit it also serves as a method of evaluation of individual progress: but it must be understood that this is just a secondary effect, and it is not the main goal for this in-class tests.

Students tend to prioritize being evaluated and getting a good score over learning the content of the course. Of course this is wrong, the final score is not a goal, it is, as the tests, just a didactic instrument, being employed for the only real, final goal, that is, making sure that each student learns as much as possible the contents of the course, and improves his skillness and working capability. 

The "flipped classroom" concepts exacerbates this fact, which often is not clearly make evident to students. For years, they are fooled, thinking that the ultimate goal is to pass each exam with a good score. With traditional didactical methods this is indeed a viable approach, as it forces the students to apply with continuity and proper effort for passing the exam and getting a good score, whilst in a flipped classroom often the result is that students which did apply a strong effort get a bad score, and conversely students which are pulled by colleagues, applying minimal effort, get better scores.

If the score was the real goal, this could be considered unfair, and in fact many students often complain about the "unjust score" given to colleagues which "applied less".

But in the end the flipped classroom provides a general better level of understanding and better skillness and capabilities to a larger number of students, as a number of independent, double-blind tests did proof. And as the score, in reality, is just a didactical tool, and has no real value, it must be accepted that it is fair, in reality, that the "best" students help their colleagues which have more difficulties, even if in the end this will result in better scores for them. Nothing provides better training and makes difficult topics easy to understand as having to explain them to more stupid colleagues. And it is a good lesson of life seeing them passing ahead, rewarded with an higher score...

The "flipped classroom" approach makes use of the audio-video recordings of the lessons made during previous years. It is expected that, prior of each lesson, each student downloads and watches the recordings providing the theoretical background for each lesson. Of course, this requires a total time which is more than double, compared to a traditional course: for each 4-hours didactical unit, the student needs to waste approximately 3 hours listening to the audio-video recordings and additional 2 hours for studying the notes and the Powerpoint slides, and then of course they must attend to the in-class activity (3.5 h): so each didactical unit requires a minimum of 8.5h instead of 4h. Indeed, in this way each student is allowed to take his own time for listening to the lessons and studying the downloaded material...

This also means that the theoretical explanations will be completely avoided in class, being replaced by a very quick recall, at the beginning of each lesson, of the physical quantities which will be employed and their definition and measurement units. Most of the time will be spent making exercises or practical activities (sound recordings, acoustical measurements, and so on). Each lesson will end with an in-class test, where each student will proof how much he did study before coming to class, how well he did understand what is done in-class and how effectively he can manage the practical usage of theory.

During the in-class activity (and during the in-class test) it will possible to work with traditional methods (pen, paper, an handheld calculator); however, every student is warmly encouraged to bring into the classroom his own personal computing device (laptop, tablet, smartphone), capable of WiFi connection to the University network or direct access to Internet. Such a device will be useful for performing the practical activities (acoustical measurements, calculations), provided that suitable software is installed.

During the in-class activities and test the students will be encouraged to cooperate each other: it is not an exam, where it is forbidden to copy! Also the interaction with the teacher will be informal and bidirectional, the class activity has little to do with a traditional "frontal" lesson, where the teacher talks, and the students listen (or sleep)...

There are several rules for the in-class tests: 

  1. The input data of the numerical problems are usually dependent on the 6 digits of the matricula number, which are "labelled" in sequence (ABCDEF). For example, if the Matricula number is 123456, then A=1, B=2, etc. - a typical input datum could be: L= 100+F*2 dB, which results in L=112 dB if F was 6. In some cases two digits are employed as a single number: L=100+EF dB results in L=156 dB, if E was 5 and F was 6. Please note, it is NOT the same as L=100+E*F dB, which would result in L=130 dB.
  2. The evaluation of the result is very rigid, as it is being performed by means of an Excel spreadsheet. So the results must be entered VERY EXACTLY: the number must be written with the degimal point (not with a comma); then there must be a space, and finally the correct SI unit (with proper smallcase/uppercase lettering). Examples: 93.5 dB(A) - 340.321 m/s - 5.68E-6 W/m2 - note that the number must follow the Excel notation.
  3. In case of problems about the scores obtained, the student should ask for explanation by E-mail, and NOT during in-class activity.

The final prize will be to avoid the traditional written exam for a (possibly large) number of students, who follow a  "large percentage" of the lessons and get "good-enough" scores during the in-class evaluation tests. It is not possible to fix in advance the thresholds about the minimum number of presences and about the minimum score for being exempted by the written exam: these values will be computed only at the end of the course, based on a statistical analysis and a not-linear weighting of the results of the individual tests. There is no point to ask in advance about the values of these thresholds, it is substantially impossible to know them in advance, so any request will simply be ignored.

Unfortunately the "flipped classroom" approach will probably result in some difficulties for people who cannot attend to most of the lessons.

As this is a course which is optional for every student, those who cannot attend most of the lessons are warmly suggested to choose a different optional course! The same holds for people who do not like the "flipped classroom" approach, or who are not happy to cooperate with colleagues during the in-class activity.

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Method of Examination

The method of examination is quite standard: a written test, based on exercises, followed by an oral final exam, mostly theoretical. This method is unchanged in the last 7 years.

However, thanks to the in-class tests, it is expected that a significant number of students can be exempted from the written exam.
 

In class tests and exemptions

  • A first group of "top students", getting a score 27 or larger in the in-class tests, will be fully exempted from the written test, and will be subjected directly to a quick oral question. This can only improve the score, or perhaps leave it unchanged, but the score cannot be reduced. However, if the student cannot answer at all, or, even worst, provides completely wrong answers, he will be rejected and invited to come at least two weeks later for a new oral exam.
     
  • A second, larger group of students, who get a score equal to 22 to 26 points thanks to the in-class test, can perform a new written test, in order to increase the voting base for the oral examination: if this new written test leads to a result which is worse than the score resulting from then in-class test, the latter can be used as the starting score for the oral examination. In essence, there is no risk to redo the written exam. Consequently, it is expected that many of these students will prefer to repeat the written test, in order to improve their base score and show their level of knowledge of the subject. The oral exam will be easy and quick for those who redo the written exam, without the risk of score reduction, exactly as for the students of the former group, even if the score has not been improved thanks to the written test. Instead, it will be longer and deeper for those who present themselves directly to the oral without attempting to improve the score of their written exam, and in this case the "normal" evaluation approach is employed, so that if the oral is bad, the score of the written test can be diminished by up to 5 points.
     
  • A third group of students who get a score equal to 18 to 21 points thanks to the in-class test must make mandatorily the written exam during normal exam sessions, for getting possibly a better starting score prior of the oral exam. However, in the case the written exam results in a score which is  worst than the one obtained with the in class test, also the students of this third group are allowed to employ the score of the in-class test as the starting score for the oral exam. In any case these students will be subjected to a full oral exam on the whole program, and with the possibility that a bad oral exam causes the reduction of the score of up to 5 points
     
  • the benefits achieved through the test in class by the above three groups of students remain for the entire academic year 2015/2016, until the last exam session of the spring 2017. They also remain unaffected even in case of rejection or non-acceptance of the final score.

For the remaining students the score obtained with the in-class test, being smaller than 18, becomes irrelevant; the examination is the traditional one, as described in the following, divided in two parts: some written exercises to be solved numerically, followed by an oral examination about theory. And the oral exam is allowed only for students who get at least 15 points in the written part.

 

Written exam

All the student must be present at the nominative call at 09.00, and they must sign the presence sheet when called. Who misses this will not be verbalized, and hence he will have to repeat the exam during the following appeal. Who is late at the nominative call looses the right to be examined in that day.

The written exercises are to be completed in an one-hour time limit, typically starting at 9.15, after the nominative cal procedure is completed. After a few minutes for the correction of the exercises, the oral examinations start (typically around 10.30).

For the written exam, the student is required to carry a pen and an handheld calculator, as well as charts, tables, notes, etc...

During the written exercises it is possible to employ all of the above material, including notes and/or textbooks; instead, during the final oral question, the student is not allowed to consult his/her notes or books, but he/she can still employ charts and tables - so it is advisable to keep them separate from the notes.

The usage of computers, tablets, smartphones or the like is strictly forbidden during examinations.

If the student carries such devices with him/her, including cell phones or smartphones, the devices must be kept switched off (NOT just in standby mode) during the whole duration of the exam.

Who infringes this rule will be immediately expelled from the classroom and consequently rejected, even if the device was not being used.

Exception to this rule is allowed only for students with certified Learning Disabilities (LD, DSA in Italian), who are invited to contact the teacher before the exam, possibly by Email or in person, instead of passing through the LD Office "Le Eliche".

For the written exercises, each student is given two pieces of paper: the examination form, which includes the problems and there are spaces for writing the results, and one 4-faces "protocol" foil, where the student should write clearly the passages required for getting the solutions. Both sheets must carry, since the beginning of the exam, name, surname, matricula and signature of each student. It is forbidden to write on anything else than the "protocol" sheet: if one is not enough, additional "protocol" sheets can be asked to the examiner. All the "protocol" sheets must be given back together with the examination form.

The written exercises typically provide a maximum score of 30 points. At least 15 points are required for passing the written exercises and being admitted to the subsequent oral question.

At least one written exercise is always mandatory, even for students who take the examination during receiving hours (see later).

For optimal training to the exercises, it is strongly discouraged to "study" the solution of already-solved problems. The only way to be trained correctly is by attempting to solve problems without any preliminary knowledge of the correct solution. For this, it can be useful to download the text of the problems which were employed in past years, which can be downloaded here:

   OLD EXAM EXERCISES
 

 

Oral exam

Each oral exam is typically shorter than 15 minutes. In most exam sessions, as the oral exams start around 10.30, all the students are examined before lunch. Only when the number of students is very large, some of them will be examined in the afternoon. It is generally not allowed to make the oral examination in a day different from the written exam, so the student should be trained to sustain both parts of the exam in the same day (except in the case of exemption from the written exam, as described earlier).

It is always mandatory to satisfactorily answer to at least one oral question, typically on theoretical topics, even for students who passed the written exercises with maximum score.

The evaluation of the oral examination, which usually is positive, in some cases can provide a NEGATIVE score, reducing the score obtained in the written part. Normally a range of +/-5 points is available. Only in very exceptional cases this range can be expanded to +/- 10 points, based on the sole evaluation of the examiner.  And, independently from the sum of the scores, if the oral examination is judged unsatisfactory, the student can always be rejected.

So students must train themselves to sustain a formal oral examination on theoretical topics, and are discouraged to only train on exercises. Please, note that an oral question is considered satisfactorily answered even if just a minimal answer is given, provided that the student proofs to know and use proper words (names) associated with the physical quantities, and to know the corresponding definitions, physical meaning and measurement units. It is NOT required to memorize complex formulas or numerical values, the student should consult his tables of formulas and values during the oral examination. Conversely, it is well appreciated to be equipped with a good set of tables and charts, proofing to be able to retrieve quickly the required information from them. During the oral examination it is not usually required to do numerical computations: however it is always useful to keep the handheld calculator at hand.

Students of the Engineering and Physics courses are requested to use English both for the written and oral parts of the examination, even if they followed the course several years ago, when it was named "Acustica Applicata" and taught in Italian.

For optimal training to the oral examinations, students are encouraged to assist to the previous session of exams.


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Dates of exams

Date

Day

Hour

Place

29/01/2016

 Friday 9.00 Aula A1

19/02/2016

 Friday 9.00 Aula A1

01/04/2016

 Friday 9.00 Aula

01/07/2016

 Friday 9.00 Aula

15/07/2016

 Friday 9.00 Aula

16/09/2016

 Friday 9.00 Aula

30/09/2016

 Friday 9.00 Aula

Currently, the Easytest software does not allow to plan the exam dates and classrooms with large advance, so the students are kindly requested to be patient, and do not stress the teacher asking to fix the exam dates. This is currently outside the control of the teacher, and such requests are absolutely not useful.

The students are simply recommended to check this web page often, when the dates are fixed they will be posted immediately here. In any case, the teacher will not answer to requests of fixing additional exams, as it is possible to make exams every week, during the receiving hours, as explained below.

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Electronic registration of exams

Starting in January 2015, the standard procedure for registering exams during the official exam dates shown above is the electronic one, employing ESSE3 (https://unipr.esse3.cineca.it).

This means that every student must obligatorily enlist for the exam on Esse3. And for doing that, the student must have got an approved study's plan, and must have completed the evaluation questionnaire for this course.

Students who cannot enlist on Esse3 cannot make the exam: in no case the teacher will perform manual verbalization or wait to register the exam until a following exam session. Please contact the didactical secretary (ex Presidence office, didactical building) for problems with Esse3, and not the teacher, who has no control on that system.

Being more clear: even if the secretary tells that they cannot solve the problem and to contact the teacher, this does not means that the teacher can accept students who are not enlisted to ESSE3 during official exam dates. In these dates, due to the large number of students, electronic registration only is allowed, and this requires that the students are enlisted on ESSE3.

If, for any reason, the student cannot do that, there is no point contacting the teacher, as he cannot do anything for solving this problem.

The only possibility could be to make an exam during receiving hours, as explained here below, as these exams have yet on-paper registration. However, if the student has an irregular administrative position, even doing the exam during receiving hours can be a problem, as the secretary will later void the exam, which must be repeated. Each student must be sure to be allowed to make the exam in a given "receiving hours" date before booking an exam in that date.

 

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Examinations in receiving hours

Students may ask the teacher to take the exam in dates different from the "official" ones shown above, by sending an E-mail for according about date and site for the exam. In particular, the general rule is to perform these exams during receiving hours, even if it is always required to get a preliminary agreement by E-mail.

Every student is required to check with the Secretary that he is allowed to take the exam on the chosen date - if he is not allowed, the Secretary cancels the exam's recording, and it must be repeated ....

For clarity: who does the exam in receiving hours gets immediate "on paper" verbalization of the examination carried out. Therefore it needs to be ensured that the student is allowed to take the exam on the date on which it actually takes place. Under no circumstances the examinator will leave a "suspended verbalization" until the next exam session. Who is not allowed to take the exam on a certain date, of course cannot do it at that time. These rules were made for presumably good reasons, so they should not be circumvented. If they are deemed inappropriate, students should ask the Didactical Council to change them, rather than bombard the lecturer with requests of improper circumvention of the rule...

On the other hand, these rules are complex, and the position of each student is, in general, different from that of another. I do not have the knowledge and the tools to determining who is entitled to make an examination on a certain date and who is not. It is useless to ask me, for me everyone can do the exam at any time... Every student must check with his Secretary, to avoid that the examination is cancelled, after being done in a "not allowed" date.

Due to the possibility of making exams all around the year, there is absolutely no point about creating "extraordinary exam sessions".  Any request of this type will be simply ignored. The only exception to this rule is when the Didactical Council approves a one-week break during the lesson period, and invites each teacher to set an extraordinary exam session within that break period. Except for this case, no request coming directly from students will be taken into account, as they are already allowed to make the exam with the method described here during receiving hours.

Exams done in receiving hours are still registered by means of old paper verbals. However, this does not means that students who cannot enlist for normal exams on ESSE3 are automatically allowed to make the exam during receiving hours: if the position of the student is not complying with regulations, so that he cannot enlist on ESSE3, this means that he is not allowed to make this exam. Even if the exam is registered on paper, the secretary will cancel it, and the exam must be repeated...

So please, book for an "exam in receiving hours" only after checking that the administrative position is regular and that the exam is allowed in the date chosen. These conditions must be verified with the didactic secretary, not with the teacher, who has absolutely no competence on administrative stuff.

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Recommended textbooks

The official textbooks for the Applied Acoustics course are:

These books are in Italian - free download in PDF format, you can also request for a free hardcopy to Rockwool. Thanks Rockwool!

The books RECOMMENDED (not mandatory) for thorough preparation of the exam are:

Additional support material for the course (Excel spreadsheets, WAV files, etc..) used during the lessons is available in the "Public" section of this website:
http://pcfarina.eng.unipr.it/Public/Acoustics-Course/ - It is recommended to download especially the Excel spreadsheets containing the exercises done in the classroom.

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Old "on line" notes (in Italian)

It can be useful to download the material prepared some years ago for the Advanced Training Course for Competent Technicians in Environmental Acoustics , organized by the University of Parma in 2005 and 2006.

It consists of 11 lesson notes covering the first part of the program

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New "on line" notes (in English)

A good set of notes written in American English, covering the first half of the course (Noise Control) are available from the site of prof. J. S. Lamancusa at Penn State University: http://www.me.psu.edu/lamancusa/me458/ Please, have a look at the animations on that page!

In particular, the first 10 notes, albeit not in the same order, cover perfectly the first part of this Applied Acoustics course.

Penn State notes

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Audio / Video recording of the lessons

Starting from academic year 2010/2011, we are performing the audio / video recording of the lessons, in AVI format, thanks to the Open Source program CamStudio .

The following link points to a page containing a selection of these audio-video recordings, corresponding to the scheduled numbering of the lessons.

Progressive list of lessons

For each lesson the student can download:

It is recommended to use the Open Source program VLC Mediaplayer for viewing and listening to these AVI files on any platform (Win/Mac/Linux). We also recommend to first download the AVI files to a local directory, and then to open the files form the local HD employing VLC mediaplayer. Playing back directly in the browser, from the course web site, is NOT recommended...

Prior of each lesson, the students should download and watch the audio/video recording, keeping an eye on the Note, so that they will get a background, albeit crude, of the topic which will be developed in class.

The experience of previous years has shown that students who attempt to prepare the exam solely by the usage of this material have a great failure ratio.

This is exacerbated with the "flipped classroom" didactical approach employed since academic year 2014/2015, because also the students not attending the lessons in class will be required to proof the same operational skills as their colleagues who are training in class. Students of previous years who did not follow the lesson in class, are warmly suggested to follow again the course in-class.

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Software

This is the list of software used during the lessons and lab sessions, with links to download them.

Name

Description

Link

 Adobe Audition

Program for sound recording and playback, waveform editor, simple FFT analysis, sonogram, multitrack recorder, and it can act as a "host" program for plugins in three different formats (VST, Direct-X, XFM).

The recommended versions are 1.5 (the best one) and 3.0 (if you need ASIO). An unrestricted version of Audition 3.0 can actually be downloaded for free from the Adobe web site, after registering.

Please DO NOT USE version 2.0 or version CS 5.5 and following, as these are NOT compatible with Aurora plugins. And please, install the English version of Audition (and of any other program offering a multi-language interface!).

Furthermore, it is always mandatory to set the Regional Settings of your operating system (in Control Panel) to English-UK or similar, NEVER in Italian! This affects decimal separator, date, time and number formats... If this setting is incorrect, operations such as Copy and Paste to another program (i.e., Excel) are going to fail....

http://www.adobe.com/it/products/audition/

 Aurora

Suite of XFM plugins for Adobe Audition: generation of test signals (MLS, sweep) computation of the impulse response, acoustic parameters according to ISO 3382, calculation of inverse filters. Includes a fast convolution module, which is employed for performing auralization. 

See the warnings above for Audition regarding program version and regional settings.

Aurora is shareware, with a "russian roulette" annoying-by-purpose feature.

http://www.aurora-plugins.it

 AudioMulch

VST-Host general purpose program, programmable through the construction of block diagrams, coming with a wide range of effects. Easy to use. Versions for Windows and Mac.  90 days free trial.

http://www.audiomulch.com

 Plogue Bidule

VST-Host general purpose program, programmable through the construction of block diagrams, coming with a wide range of effects. It is possible to create new effects. Shareware. Windows and Mac versions. It can also be used as a VST plugin inside another VST Host program. More tricky than Audio Mulch, but also more powerful.  90 days free trial.

http://www.plogue.com/

 SynthEdit

VST-Host program and compiler of VST plugins, programmable through the construction of block diagrams. Customizable interface with editable "skins". Contains an extensive library of graphical objects and of processing functions. Shareware. Better than Labview ....

http://www.synthedit.com/

 SpectraRTA

Spectral analysis in octaves, third octaves, and FFT, signal generator for acoustic testing, measurement of the reverberation time. Works with one or two channels, can be used to record and analyze WAV files.

http://www.soundtechnology.com/

 SpectraPLUS

FFT and fractional-octave frequency analysis, cross-spectrum, sonogram, waterfall, signal generator for acoustic testing, measurement of reverberation times. Works with one or two channels, can be used to record and analyze WAV files. 30 days free trial.

http://www.spectraplus.com/

 Ramsete

Simulation of sound propagation in enclosed spaces and outdoors. Calculates the impulse response, and from it derives all the acoustical parameters. Includes a 3D CAD design module and a module for mapping results in colour or by isolevel curves. It also allows for the export of impulse responses in WAV format, for performing auralization. Free trial of the "Lite" version, the crack can be found on Emule, enabling full performance.

http://www.ramsete.com

 Comsol

"Multiphysics" FEM simulator, which includes modules for Acoustics and Vibration. It allows for the study of wave type phenomena (resonance, interference, diffraction, etc..) at low and medium frequencies, using the Finite Elements method. Free trial license available for students.

http://www.comsol.com

 DISIA

The package includes Citymap and Disiapyr. These are programs for simulation of noise from road and rail traffic, which can operate both on a large scale (Citymap), and for detailed simulations (Disiapyr). They were developed as part of a DISIA project, funded by the Ministry of Environment, and are the reference computational models for the Italian fleet of vehicles. Free for academic usage (password required).

http://pcfarina.eng.unipr.it/Public/DISIA

Note: the above software is commercial software or shareware (excluding the last one, which is free, but the use is restricted to institutional goals of public administrations, and protected by password), although most of them provide a free running mode for a limited period of time, or indefinitely but with reduced functionality. Users who do not like this approach, can use the following open-source software:

  Audacity

Simple "open source" program for sound recording / playback, with many editing effects; it also operates in multitrack. Supports all platforms (Windows, Mac, Linux). A port of Aurora plugins for Audacity is under development (thesis available).

A special version of Audacity containing some of the Aurora modules so far developed can be downloaded HERE.

Please note that these Aurora modules DO NOT WORK on other versions of Audacity...

http://audacity.sourceforge.net/

 

http://pcfarina.eng.unipr.it/Public/Aurora-for-Audacity/

  Sonicbirth

Compiler for VST and AudioUnit plugis for Mac platform, with graphical interface of "block diagram" type. Interface customizable using editable "skins". It contains a wide library of graphic objects and processing functions. Similar to Synthedit, but less powerful and versatile.

http://sonicbirth.sourceforge.net/

 RoomEQ

JAVA application for the measurement of the impulse response of a room with Exponential Sine Sweep and calculation of equalization filters for sound systems. It includes a realtime spectrum analyzer, a realtime Sound Level Meter, and a reverberation time measurement module.

http://www.hometheatershack.com/roomeq/

 Psysound

Matlab suite of modules, with user interface developed for processing of audio signals and acoustic analysis of all kinds

http://psysound.wikidot.com/

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Thesis Topics

A variety of thesis topics is available, for all the branches of Engineering. Some are listed below, but others are available, so it is recommended to contact the teacher for more information.

Attention: an Applied Acoustics thesis can only be experimental, and thus requires hard work: so, if you are looking for a "light and fast" thesis, you're in the wrong place ...
 

Title

Description

Suggested degree

Digital Audio Amplifier  

Research carried out in collaboration with ASK Industries, Reggio Emilia, looking for a student who is willing to learn programming DSP devices "embedded" in automotive audio amplifiers. The DSP built into the device could be used for active noise cancellation, for dynamically changing the equalization curve and the gain as a function of the background noise, and for the correction of non-linear response of loudspeakers. The student will work as an intern at the ASK Montecavolo (RE), actively participating in the trial, and gaining professional experience in the field, which is extremely useful for subsequent job search.

Electronics, Telecommunications, Computer Science

Vehicle sound system measurement

Research carried out in collaboration with ASK Industries, Reggio Emilia. The purpose is to evaluate the perceived acoustical quality of a "automotive" sound system, based on innovative measurement techniques (STI, AQT, PEAQ) and on listening tests performed within the vehicle or in a special playback room. It employs mono recording techniques, binaural, or array of microphones. Depending on the capacity of the student, he will have to develop "ad hoc" software for measurement or analysis (in Matlab or Visual C), to define new metrics, to analyze statistically the results of subjective tests, and to design new strategies for temporal, spectral and spatial equalization of the sound reproduction system.

Electronics, Computer, Telecommunications, Mechanical

Active Noise Cancellation

Research carried out in collaboration with ASK Industries, Reggio Emilia. The purpose is to design and build a prototype of device, based on DSP, for processing in real time the signal captured by a primary microphone. The filtered signal is output from one or more loudspeakers, creating an antiphase sound field that cancels the original noise. The student must possess the ability to program a DSP (also using high-level interfaces such as "block diagram"), to carry out measurements of impulse response (Aurora) and of spectra (SpectraRTA), and also to work in the workshop in order to build the mechanical components of the device.

Mechanics, Electronics, Computer Science, Information Technology

Analysis of sound quality of bakery products

Research carried out in collaboration with Barilla, Parma. The purpose is the analysis and optimization of the sound created during fracture and / or chewing of bakery products (such as cookies, biscuits, crackers, sticks, etc..). Binaural recordings are employed for objective analysis of the sound produced, and tests with human subjects are performed, in order to operate a collection of questionnaires and obtain an analysis of the subjective sensations evoked while eating these products. 

Mechanics, Mechanical Engineering for the Food Industry, Information Technology, Management

Use of ultrasound in the food industry

Research carried out in collaboration with Barilla, Parma. The goal is to  evaluate the possibility of using a treatment section with ultrasound for sanitizing and / or homogenization of liquid foods, either as a single treatment, or as a treatment subsidiary to other devices. The student must work alongside a research assistant in carrying out experiments on the pilot line and in the analysis of results.

Mechanics, Mechanical Engineering for the Food Industry

Noise analysis of gear pumps

Research carried out in collaboration with Casappa, Parma. The purpose is to develop new methods of signal analysis, applicable to both the noise signal radiated during operation of gear pumps, and to the "pressure ripple" signal detectable in the delivery circuit of the pump. It is expected to obtain useful information in order to identify problems in the pump (diagnostics), and to develop new, more silent pumps and of longer duration.

Mechanical, Electronics

Analysis of the sound generated by old gramophones and radios

Research carried out in collaboration with the House of Sound, Parma. It deals with measuring the sound characteristics of old gramophones or receivers radio, part of the famous Patane' collection. The recordings could be used as such in the exhibition of the House of Sound, or even be "virtualized" making use of advanced techniques of analysis and resynthesis available in the laboratory of virtual reproduction of the House of Sound.

Telecommunications, Computer Science.

Sound reproduction using loudspeaker arrays

Research carried out in collaboration with the House of Sound, Parma. The student will have to create recordings or compositions, mostly of musical events, but also of "special effects", to play on the WFS playback systems available at the House of Sound: the WFS "white room" the "Sonic Chandelier". The student must first acquire an adequate understanding of the physical mechanisms underlying the Wave Field Synthesis, and master the system hardware and software that operate the House of Sound. Then he must create one or more "documentary soundtracks" that will be "projected" at the House of Sound.

Telecommunications, Electronics, Computer Science

Shooting techniques with virtual microphones

Research carried out in collaboration with the RAI Research Centre, Turin. The purpose is the development of a device for recording "live" events such as concerts, sporting events, theatre, etc.., in all cases in which microphones located close the sound sources cannot be employed. The microphone arrays employed are the Holophone and the Eigenmike 32. The student must make a series of test recordings with these devices, process the traces recorded so as to synthesize an adequate number of virtual microphones with suitable directivity and pointing, and manage the organization of special "surround" listening tests with trained listeners specialize, with the goal to identify the best signal processing technique.

Telecommunications, Electronics, Computer

Three-dimensional measurement of impulse responses in theatres and concert halls

Research carried out in collaboration with AIDA Srl, Parma. The purpose is to develop a method of measuring acoustic characteristics of a room, making use of a new portable recording system, equipped with a tetrahedral microphone probe, called Brahma. The student must perform measurements with the "exponential sine sweep" technique in a number of rooms, comparing the results of the new technique with the traditional ones, and employing the results for designing suitable acoustical corrections, when required.

Electronics, Civil, Telecommunications

Porting of Aurora plugins under Audacity

 

The project, recently launched thanks to the activity of research assistant Simone Campanini, aims to rebuild the suite of Aurora plugins ( www.aurora-plugins.com ) as add-on modules for the open-source and cross-platform program Audacity .
The student will have the opportunity to participate in the development of new software modules, operating on the platform of choice (Windows, Mac, Linux) and to test the correct functionality by performing experiments of measurement and listening, and by comparison with the current implementation for Adobe Audition, and with cutting-edge laboratory instrumentation (Audio Precision, Bruel & Kjaer, etc..).

IT & Computer Science Telecommunications, Electronics

Porting of Aurora and X-volver plugins to VST format

 

The project, recently launched thanks to the activity of research assistant Andrea Venturi, aims to rebuild the suite of Aurora plugins (www.aurora-plugins.com ) as additional modules in VST format.
The student will have the opportunity' to participate in the development of new software modules, operating on the platform of choice (Windows, Mac, Linux) and to test the correct functionality by performing experiments of measuring and listening, and by comparison with the current implementation for Adobe Audition, and with cutting-edge laboratory instrumentation (Audio Precision, Bruel & Kjaer, etc..).

IT & Computer Science, Telecommunications, Electronics

Non-destructive analysis of frescoes by acoustic and vibration measurements

Research sponsored by the Cariparma Foundation, Parma. The purpose is to develop a new test method with very small invasiveness, aimed at locating structurally degraded areas in plaster, frescoes, mosaics, and other structures of historical value. The new method makes use of an "exponential sine sweep" signal, in order to operate with very low sound pressure level; an array of loudspeakers focuses sound waves, so that just a restricted area of the surface to be scanned is stressed, and an array of microphones (or a Laser-Doppler velocimeter) is employed in order to determine the vibrational response of a single point of the structure. The student must first operate a verification of the new method on artificial samples in laboratory, and then perform experimental tests "in situ" inside churches and other historic buildings in Parma.

Civil, Mechanical

Development of a sonar system for "sub-bottom profiling"

Research carried out in collaboration with WASS, La Spezia and Livorno. The goal is the development of a low-frequency Sonar system, operating in the audio field (1000-20000 Hz), broadband, in order to obtain a good penetration into the seabed and to view the soil stratigraphy below. The system uses an array of 16 hydrophones and an underwater loudspeaker fed with sine sweep signal. The student will have to make a series of tests in the laboratory, in the test tank and in the sea, in order to validate the operation of the system, and to process the results of the acquired traces in order to obtain three-dimensional images of the stratigraphy of the bottom.

Electronics, Environment and Territory, Computer

Development of a three-dimensional underwater sound recording system

Research carried out in collaboration with AIDA Srl , Parma. The purpose of the research is the development of a device for recording underwater the signals of 4 hydrophones, capable to determine the direction of origin of the sound, to be used for underwater environmental monitoring in marine protected areas. The student must follow the electromechanical development of the prototype and carry out the characterization of performance with in-tank testing and in-sea testing.

Electronics, Environment and Territory, Computer Science, Mechanical Engineering

Development of an "Acoustic Camera" system

Research carried out in collaboration with AIDA srl , Parma. The purpose is to reactivate the "Acoustic Camera" system that was built four years ago, making use of high quality microphones and of a new portable hardware acquisition system, which should allow to be used outside the laboratory. The student must first reassemble the system and make it operational, then verify its performances through a series of measurements to be carried out both in the laboratory, and in industrial environment. If versed in programming, the student may also participate in the development of the new real timea software, that should replace the existing Matlab software, currently capable of "off line " processing only.

Mechanical, Civil, Electronics, Computer Science

Mapping of environmental noise through measurements and simulation

Research carried out in collaboration with the Municipality of Parma, Department of Environment. It is aimed to realize a first prototype of a control unit for acoustic monitoring of urban areas, based on the assembly of already existing, low cost components. The student must make a series of surveys by placing these 10 units in the hot spots of the city, in order to achieve the noise map in the city of Parma, also making use of the simulation software Citymap.

Environment and Territory, Civil

Development of a "low cost" measurement system for building acoustic

Research carried out in collaboration with AIDA srl , Parma. This is to verify the ability to employ low-cost instrumentation, making use of digital audio equipment originally developed in the field of music, to carry out building acoustics measurements, thanks to recent technical rules which allow for the use of the exponential sine sweep signal. This makes it possible to use a small loudspeaker and low-cost digital audio recorders. The student must carry out a campaign of comparative measurements, using either the new method and the traditional one, and compare the results obtained in a number of civil and public buildings (school, hospital, etc..).

Civil, Environment and Territory

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Copyright (C) Angelo Farina - reproduction prohibited without permission.
Last revised: 15/01/2016, 20:57