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

This course is taught in English

This course can be chosen by students of  the following Post-Graduate (Advanced) Degrees: Communication Engineering, Electronics Engineering, Computer Engineering, Mechanical Engineering, Civil Engineering, Environment and Land Management Engineering, Physics, Architecture

 

 

  • Advice: here the code for direct access to the Team used for the exam on 26/02/2020: yqsg8jv

  • This instead is the link to the exam's Team, to be used after self-authorizing to it with the code above: TEAM appello 26-02-2021

  • ATTENTION !
    DO NOT send a request for accessing the team, I will NOT approve these requests. Instead you should self-authorize your access to the team, using the direct access code shown above. You should use the function called "Join a team with a code".

 

Teaching Hours:    Friday, 13.30 - 17.30 - aula 8

Beginning of the course: 20 September 2019

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 of Dept. of Engineering and Architecture.

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 post-graduate course of 6 CFUs we can only provide the methodological basis of Applied Acoustics which must then be further studied in more advanced courses, such as courses for Competent Technicians in Environmental Acoustics (typically 3-6 months) or Master Courses (1 year) available at some Italian universities, or even dedicated post-graduate degrees (2 years, for example the post-graduate (advanced) degree in Musical Acoustics of Politecnico di Milano).

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 students of Architecture and Physics).

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 in 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 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, VR, AR) 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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Didactical Approach

In academic year 2014/2015 a  "Flipped Classroom" method was adopted for the first time, and the experiment was repeated, with significant modifications, during academic year 2015/2016. During the following year 2016/2017 this course was held temporarily by the visiting professor Filippo Maria Fazi, of the University of Southampton, UK. He did come back to traditional in-class didactics, but he retained some of the best outcomes of the Flipped Classroom experiments, such as the videorecording of the lessons and the in-class intermediate tests.

Since academic year 2017/2018 we are back to traditional in-class lessons, but we retain a partial support of pre-recorded lessons which were recorded during previous years. A selection of these videorecordings is made available alongside with the Progressive list of lessons, together with other supportive didactical material (lesson notes, data files, charts, audio files, etc.).

However, these videolessons are NOT a teledidactic course. They are INSUFFICIENT for preparing properly the exam. An important part of the didactical activities are AUDIBLE EXPERIMENTS which are conducted in the classroom at every lesson, and which can only be experienced in physical presence in the classroom. Furthermore, a number of in class-tests are planned, but WITH NO PREVIOUS ADVICE. This means that only students who regularly come to lessons will have the possibility to take part to these frequent and very short in-class tests, and hence be progressively evaluated, with the goal of avoiding entirely the final exam.

Of course, students who cannot come regularly in classroom will have the possibility to study at home, and to make a traditional written+oral exam, but in this specific case this will result in a systematic handicap, affecting both the final preparation and the final score. So, if you cannot attend to a significant number of the in-class lessons and tests, it is warmly suggested to choose another course, if getting an high final score is a relevant expectation for you (it was not for me, when I was a student, however I see that for a number of students the score has some significance).

In-class tests: a didactical tool, more than an evaluation tool. Some hints:

  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 decimal 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. The correction is performed typically during the following lesson.
  4. In case of problems about the scores obtained, the student should ask for explanation by E-mail, and NOT during in-class activity.
  5. During the in-class test the students are allowed, and warmly encouraged, to employ personal computing devices (laptop, tablets, smartphones) also connected to the Internet. These can be used for doing calculations, for accessing the online didactical resources (slides, notes, tables, charts, Excel spreadsheets) and also for free search on the Internet (Wikipedia, internet repositories, etc.).
  6. However, these electronic devices should not be abused, employing social networks or other communication networks finalized to getting help in the solution of the problems. Students caught doing such unethical behaviour will be reported to academic authorities, and risk severe consequence, such as the complete cancelling of their entire academic career and the expulsion form the University of Parma. Students are warned of the high risk that these electronics devices can cause, so use them very carefully, because the risk is strongly exceeding the potential advantages that an unethical behaviour can provide.
  7. Students making use of their personal computing devices are warmly encouraged to use them also for submitting "online" the results of the tests, by filling up a Google Form. The link to it will be provided just at the moment of the test, and will be deactivated after a few minutes, at the end of the test. For filling up the questionnaire each student must first login his web browser to Gmail, using his student's credentials (name.surname@studenti.unipr.it). The following link provides a test questionnaire, for checking your connectivity and your capability of compiling a Google Form properly:

The final prize will be to possibly avoid the traditional written exam.

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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 question, mostly theoretical. The oral question only comes after the written exam, usually on the same day. This method is unchanged in the last 9 years.

However, thanks to the in-class tests, it is expected that a significant number of students can be exempted from the written exam, and make directly just the final oral question. However, whatever the result of the in-class test, each student can always choose to make also the written exam, with the goal of improving his score.

These students will still have the possibility to improve their starting score, by making the written exam the same day as the final oral question, with the safety that, if the written exam results in a score lower than the score of the in-class test, the latter will still be considered as the starting score for the oral questions. In practice you can only get a better score, not worst; hence there is no risk attempting to improve your score with the written exam.

The written exam is made typically of 3 or 4 exercises, with numerical solution, similar to those of the in-class tests. It lasts one hour, the correction is immediate, and after this the students perform immediately the final oral question.

The final oral question is simple and short, an typically takes no more than 5 minutes. It causes a small variation (positive and negative) of the score already obtained with the written exam, which remains the most relevant part of the evaluation procedure. Typically the final oral question gives a maximum variation of +/- 3 points, which only exceptionally can go up to +/- 5 points.

If the total score exceeds 30, the "cum laude" is obtained automatically. It can also be given to students reaching exactly 30 points, if the oral exam was particularly brilliant.
 

Written exam: rules

All the students 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 call 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.

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: rules

Each oral exam is typically shorter than 10 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 or the in class tests 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 +/-3 points is available. Only in very exceptional cases this range can be expanded to +/- 5 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, nor demonstrations; the student can 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. Students of Architecture can ask to make the oral exam in Italian, albeit doing it in English is appreciated and suggested.

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


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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 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 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.

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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 will be made available in the "Public" section of this website:
http://pcfarina.eng.unipr.it/Public/Applied-Acoustics/2018/ - It is recommended to download especially the Excel spreadsheets containing the exercises done in the classroom.

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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 downloadable material have a great failure ratio. Better to come to classroom and participate actively to the lessons...

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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 linked here beside, after registering.

Please DO NOT USE version 2.0 or version CS 5.5 and following (CC), 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....

https://helpx.adobe.com/creative-suite/kb/cs2-product-downloads.html?promoid=19SCDRQK

 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/

 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

 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

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

Use of ultrasound in the food industry

Research carried out in collaboration with GEA Niro Soavi, 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: 19/09/2019