Angelo Farina

Università di Parma | UNIPR · Department of Engineering and Architecture

The purpose of this article is to detail and evaluate three alternative approaches to soundfield visualization, which all employ the use of spatially localized active-intensity (SLAI) vectors. These SLAI vectors are of particular interest, as they allow direction-of-arrival (DoA) estimates to be extracted in multiple spatially localized sectors, su...

This paper presents two real-time audio plug-ins for processing sensor array signals for sound-field visualisation. The first plug-in utilises spherical or cylindrical sensor array specifications to provide analytical spatial filters which encode the array signals into spherical harmonic signals. The second plug-in utilises these intermediate signa...

This paper was the recipient of the AES 144th Convention Best Peer-Reviewed Paper Award.

This paper presents an experimental study of vibrations of the cone of loudspeakers. Measurements of the axial acceleration have been performed in hundreds of points on the surface of the cone employing a Laser Doppler Vibrometer and using the exponential sine sweep excitation signal. The recorded signal has been transformed into an impulse respons...

Many societies give special importance to places where echoes are generated, and often these places receive special treatment including the production of rock paintings in them. The identification of the exact places where echoes come from, or echolocation, is an ability only shared by a few individuals in each community. Unfortunately for archaeol...

This paper presents an experimental study of the main causes of scrap during the production of a typical midrange loudspeaker. After analyzing the most critical components of a transducer, various samples with reference and defected components have been built and characterized in terms of frequency response and distortion. In addition, a second set...

Multichannel recordings are usually performed by means of microphone arrays. In many cases "sparse" and discrete microphone arrays are used, where each microphone is employed for capturing one of the channels, which in turn is routed to one loudspeaker. However, also the usage of "dense" microphone arrays has a long history, dating back to the firs...

The evaluation of room acoustics characteristics has been thoroughly described in several papers since 60-ies. Moreover, the ISO 3382 standard describes several acoustic parameters and their measurements. However, there is only a few information about the methods of preprocessing the impulse responses (background noise compensation) that are requir...

The evaluation of room acoustics characteristics in rooms has been thoroughly described in several papers since 1960s. Moreover, the ISO 3382 standard describes several acoustic parameters and their measurements. However, there are only a few information about the methods of pre-processing the impulse responses that are required before calculating...

The urban landscape is constantly changing: habits and customs of the people, transportation, residential areas and industrial ones change themselves. From “visual” point of view, the number of media that allow us to keep track of the changes (photo and video) increases but it’s not the same for the “acoustic” point of view. Almost all sounds and n...

The analysis of the sound field's 3D properties has been strongly improved in recent years, after spatial properties of sound propagation have been acknowledged to be important during the design or correction of theatres and auditoria. Besides, a proper assessment of spatial accuracy is requested for 3D sound reproduction systems, initially designe...

This paper presents the mathematical and physical framework of a new technology, named SPS (Spatial PCM Sampling): it is the equivalent, in a two-dimensional spherical-coordinate space, of the traditional PCM representation of a waveform (in the one-dimensional time domain). It is nowadays possible to record an SPS multichannel stream (also called...

The paper presents a case history: the acoustical analysis of a rectangular auditorium. The following acoustical parameters were evaluated: early decay time, reverberation time, clarity, definition, and center time. The excitation signal was linear sweep sine and additional analysis was carried out: peak-to-noise ratio, reverberation time for empty...

Boat noise represents a chronic source of harassment for fish species, whose communication for inter- and intrasexual selection is based mainly on low-frequency sound signals (Amorim 2006). Investigating the impact of boat noise on target fish species is particularly relevant for coastal marine protected areas (MPAs), which are biologically rich lo...

In order to find a possible correlation of objectiv e parameters and subjective descriptors of the acou stic of theatres, auditoria or music hall, and so to perform meaningf ul listening tests, we need to find a reliable 3D a udio system which should give the correct perception of the dis tances, a good localization all around the listener and a na...

The paper describes the results of a subjective evaluation experiment: two methods for recording a three-dimensional sound field and for reproducing it through loudspeakers in a proper listening room are compared. The first method is the binaural method known as Stereo Dipole, based on digital filtering of binaural recordings or binaurally synthesi...

The sound scattering properties of diffusing panels are actually very difficult to measure and to predict. Furthermore, an unique, co mmonly accepted "diffusion coefficient" has not been defined yet. In this paper the Wave Field Synthesis approach is employed for the experimenta measurement of a physically defined diffusion coefficient. The results...

A new method for recording the spatial properties of a soundfield, or for generating a synthetic three-dimensional soundfield, is described. The spatial distribution of sound waves passing at a point in space is sampled by means of a number of virtual super- directive microphones, covering almost uniformly the surface of a sphere. This corresponds...

1. Il teatro (da [1]) Il Teatro alla Scala di Milano, citato spesso semplicemente come La Scala, oltre ad essere uno dei teatri più famosi al mondo è conosciuto come "il tempio della lirica"; si-tuato in una delle piazze maggiormente frequentate ed eleganti della città, l'omoni-ma Piazza della Scala, dalla quale prende appunto il nome. L'attuale st...

1. Il teatro (da [1,2]) Il Teatro Municipale di Reggio Emilia, intitolato oggi a Romolo Valli, sorge su una delle più importanti piazze cittadine, sulla quale si affacciano l'altro teatro cittadino, il Teatro Ariosto, la Galleria San Rocco e i Giardini Pubblici. Il Teatro Municipale è un teatro d'opera e concerti. Figura 1 – Sala e facciata del Tea...

Gli array lineari a spaziatura non costante (NULA) risultano essere un buon compromesso tra prestazioni, da una parte, e costo/complessità del sistema dall’altra. Un array a spaziatura non costante impiega un numero di trasduttori inferiori rispetto ad un sistema a spaziatura costante (ULA). In questo lavoro gli autori descrivono sia la costruzion...

The authors developed a new measurement system, which captures 32-channels impulse responses by means of a spherical microphone array and a matrix of FIR filters, capable of proving frequency-independent directivity patterns. This allows for spatial analysis with resolution much higher than what was possible with obsolete sum-and-delay beamforming....

A 32-capsules spherical microphone array was employed for analyzing the spatial properties of the sound field inside a car. Both the background noise and the sound generated by the car's sound system were spatially analyzed, by superposing false-color sound pressure level maps over a panoramic 360x180 degrees image, obtained with a parabolic-mirror...

Barriers employed for road traffic noise reduction can be characterized by two indices: reflection index for sound re-flection and insulation index for airborne sound insulation. They can be measured following the method described in CEN/TS 1793-5 standard, based on impulse response measurements employing a pressure microphone. The method mandates...

The short-term behavioural effects of two types of boat noise were tested on Gobius cruentatus and Chromis chromis, i.e. one permanently and one temporarily benthic vocal fish species living inside the WWF-Natural Miramare Marine Reserve (Northern Adriatic Sea, Italy). The underwater noises produced by a 26-m tourist ferry and a 5-m fiberglass boat...

In this paper we investigate about the usage of spectral smoothed FIR filters for equalizing a car audio system. The target is also to build short filters that can be processed on DSP processors with limited computing power. The inversion algorithm is based on the Nelson-Kirkeby method and on independent phase and magnitude smoothing, by means of a...

Musikverein is among the best concert halls in the world. But the hall is also employed for open-to-the-public ballets. All seats in main stalls are removed, and packed under the wooden floor thanks to a large opening. Detailed acoustical measurements have been performed, with the aim of evaluating the different acoustical behavior with and without...

The paper reports the first results of listening tests performed with a new software tool, capable of not-linear convolution (employing the Diagonal Volterra Kernel approach) and of time-variation (employing efficient morphing among a number of kernels). The listening tests were done in a special listening room, employing a menu-driven playback sys...

Traditional methods for measuring impulse responses in rooms provide detailed time and frequency resolution, but very poor spatial information. On the other hand, when a disturbing echo or discrete reflection is found, it would be very useful to be able to understand its exact direction-of-arrival. And detailed spatial information is also required...

A "sonic chandelier" has been designed and manufactured to be installed in the new "Casa del Suono" in Parma. This museum will be an exhibition of sound reproduction devices from the 20 th century, and a multi-channel audio laboratory as well. The chandelier is a 64-channel, dome shaped array of 228 speakers suspended in the center of the main hall...

Traditional impulse response measurements did capture limited spatial information. Often just omnidirectional sources and microphones are employed. In some cases it was attempted to get more spatial information employing directive transdudcers: known examples are binaural microphones, figure-of-8 microphones, and directive loudspeakers. However, th...

A new campaign of experiments was run on the floor of a large room to obtain a long enough anechoic time window: this permitted to study the first reflection from the panels themselves and their diffusion uniformity. The results are discussed, comparing them with past measurements and with the ones from a simplified set-up with a smaller geometry....

The largest part of who seats in theatres or in auditoria has not an optimal perception of sound, because of hearing loss. So, in order to find out a correlation between objective parameters and subjective descriptors, executing therefore meaningful listening tests, we need first to study the perception of the customer. For this purpose, selected t...

CORRELATION BETWEEN SUBJECTIVE DESCRIPTORS AND OBJECTIVE PARAMETERS OF THEATRES AND AUDITORIA ACOUSTICS SIMULATED WITH BINAURAL SOUND SYSTEMS

Il lavoro riguarda il monitoraggio del clima acustico delle scuole di proprietà del Comune di Parma e l’analisi dei dati acquisiti al fine di determinare una classifica di priorità per gli interventi di mitigazione da eseguire nei vari plessi scolastici. Lo studio, concentrato sia sugli spazi interni utilizzati per scopi didattici che sulle aree co...

With the advent of novel p-u probes the sound intensity technique is having a new flourishing. In particular this approach can be used also in the characterization of the acoustical properties of surfaces. This work applies the "transfer matrix" notation to obtain the complex surface properties after sound intensity measurements are performed insid...

Whilst currently available programs for computing noise maps become even more complex, there are cases where the usage of highly detailed algorithms and procedures is meaningless, because the input data for such processing is simply not available. So it is often seen that a very complex and theoretically very accurate simulation system is providing...

Head-Related Impulse Responses (HRIRs) measurement systems are quite complex and present long acquisition times for an accurate sampling of the full 3D space. Therefore HRIRs customization has become an important research topic. In HRIRs customization some parameters (generally anthropometric measurements) are obtained from new listeners and ad-hoc...

Nowadays it is possible to measure room impulse responses inside famous theatres and concert halls, and use them as filters for applying high quality reverberation to recordings and soundtracks. However, also spatial information can be measured and replicated this way, once the concept of omnidirectional source and receiver has been deleted. The pa...

Following previous investigation, carried out at the University of Parma in 1999 and 2000, LAE (Laboratory of Acoustics and Electroacoustics) started a new measurement campaign to compare with the original results on the same type of diffusor panels, to verify AES-4id-2001 measurement standard and to investigate the nature of scattering phenomena i...

Audio reproduction of a movie inside a not dedicated room is critical; setting an ITU 5.1 system at home, for example, requires to place a large number of speakers around the room. But positions of speakers are often conditioned by the furniture. Bad alignment reduces spatial performances of the system dramatically.

The definition and measurement of sound spatialisation have been strongly enhanced in last years, as nowadays spatial properties of sound propagation are considered quite important during design of auditoria. Besides, a proper description of spatiality is requested during virtual audio reproduction of sound quality in dedicated listening rooms for...

Convolution using very long filters is required in order to achieve realistic artificial reverberation or spatial effects. Unfortunately, DSP (digital signal processor) platforms have limited computational power (compared with a modern PC) and consequently it is not possible to design very long filters based on typical time-domain, direct-form algo...

Car cockpit is a critical environment for music; sound reproduction is in fact quite conditioned by reflections, echoes, engine noise and loudspeakers' set up. An important technique to improve sound comfort is a spatial equalization where both magnitude and phase of signal are controlled. This technique is performed by a stereodipole system where...

For communication personnel exposed to noise emitted by headphones, the sound pressure level measured at the position of the exposed person (but the person absent) does not adequately represent the sound exposure. The first section of this paper reports comments concerning the legislation, the relevant international standards and the state- of-the-...

The paper describes the results of a comparative study between two different groups of techniques for computing Speech Transmission Index inside cars. The measurement system is composed by head and torso simulators: one group is composed by techniques based on measurement of the impulse response that directly includes background noise; on the contr...

The acoustical zoning of the city of Chioggia (Venezia) has been based on the areas defined by the city plan, on the density of population, of office buildings, of shops and factories, and olso of activities concerning tourism. All the areas have been firstly assigned to the different classes in relation to the results of the statistical examinatio...

Noise and vibration control requirements for multiplex cinemas are normally very strict. Inside the rooms, low background noise and vibration levels below the perception threshold need to be guaranteed. The noise and vibration sources could be external (road, rail and air traffic) and/or internal (adjacent cinema rooms, escalators, car parks, air c...

Il rischio a cui sono esposti i lavoratori che impiegano dispositivi di ricezione è stato sottovalutato in quanto la strumentazione impiegata per la misurazione e la valutazione è spesso differente da quella normalmente utilizzata. In questa relazione viene indicata una diversa metodologia sperimentale e vengono riportati i risultati di sperimentaz...

The paper describes the recording/reproduction technique and the subjective listening experiment aimed to the assessment of the effect of the background noise on the perceived quality of the sound being reproduced inside a car. The noise inside 3 different cars was recorded at various speeds both with a binaural microphone and with a Soundfield mic...

The paper discusses the implementation of various possible DSP algorithms on low-cost platforms suitable for mass series production of automotive sound systems. The analysis takes into account traditional IIR and FIR filtering schemes, dual-rate and hybrid approaches, and new algorithms such as Warped FIR (WFIR) or frequency-domain partitioned conv...

Il rischio a cui sono esposti i lavoratori che impiegano dispositivi di ricezione (cuffie, cornette telefoniche, ecc.) è stato sino ad ora scarsamente considerato. Probabilmente perché le modalità di misurazione e valutazione del rumore sono in questo caso complesse e certamente difformi da quelle usualmente impiegate. In questa relazione vengon il...

To expand the activities of Teatro alla Scala, a new theatre has been built in Bicocca. The intention was to design and build a rather large hall suitable for opera and symphony concerts. A hall of 2385-seats with a moderate fan shape was built. It is a large reverberant volume with various diffusive devices distributed on the walls and the ceiling...