Lamberto Tronchin

3D Sound Characterisation in Theatres Employing Microphone Arrays

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 designed for acoustical virtual reality and now also employed in the entertainment/cinema industry (Immsound, Auro-3D, NHK 22.2). Often only monoaural or binaural measurements are performed by means of omni-directional microphones and dummy heads, although international standards like ISO 3382/1:2009 also define some “truly spatial” parameters such as JLF and JLFC. The two latter parameters are derived from measurements made with a pressure velocity (p/v) microphone, but this is still a 2-channel measurement. 3D Impulse Responses (4-channel B-format) have for many years been measured and employed for sound reproduction. Recently, higher-order 3D Impulse Responses have been measurable thanks to the availability of compact microphone arrays employing a much larger number of transducers. In this paper, two procedures for measuring and analysing the complete spatial sound information are presented, which are aimed at creating easy-to-understand images and videos showing the direction-of-arrival of the room reflections. The description of these techniques is emphasised. Furthermore, results are illustrated of experiments conducted with the novel methodologies in different rooms, including some ancient theatres.

Acoustic characterisation of “virtual” musical instruments: Using MLS technique on ancient violins*

Abstract In this paper the realisation of “virtual” musical instruments, in which the instruments are treated as linear systems characterised by their impulse response, are analysed. The impulse response is treated as a numerical filter, which is convolved with the force excitation signal coming from the chords, producing a signal containing all the acoustic characteristics of the instruments, and avoiding all nonacoustic phenomena. The aim of this work is multiple: the “virtual” instruments can be used in subjective listening tests for the evaluation of the “sound quality” of different instruments, as reported in this paper. Other possible uses are for the (real or virtual) restoration of ancient instruments, and for preliminary listening tests on newly designed instruments. Various measurement techniques of the impulse response have been tested, employing different transducers and numerical analysis. For validating the accuracy of the new technique, a subjective listening test has been conducted. Some o...

Modal analysis and intensity of acoustic radiation of the kettledrum.

The acoustical features of kettledrums have been analyzed by means of modal analysis and acoustic radiation (p/v ratio) measurements. Modal analysis of two different kettledrums was undertaken, exciting the system both by a hammer and a shaker. Up to 15 vibrational modes were clearly identified. Acoustic radiation was studied using two ways. Based on previous experiments of other researchers, a new parameter, called intensity of acoustic radiation (IAR), has been defined and measured. Results show a strict relationship between IAR and the frequency response function (FRF, which is the v/F ratio), and IAR also strongly relates the modal pattern to acoustic radiation. Finally, IAR is proposed for vibro-acoustical characterization of kettledrums and other musical instruments such as strings, pianos, and harpsichords.

On the effects of pre-processing of impulse responses in the evaluation of acoustic parameters on room acoustics

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 those acoustic parameters. In this paper, the main processing methods (based on Luneby, Chu, and Hirata methods) are analyzed. Moreover, they are compared with the Schroeder (background integrated) methods. In a further step, these methods are applied in some acoustic measurements employed in some opera houses in Italy. Finally, after a full discussion about the uncertainties that is beyond these methods, the acoustic parameters are compared with the JND that is actually accepted in the evaluation of the mono-aural, binaural, and spatial acoustic parameters.

A virtual reconstruction of the trumpet

Virtual reconstructions of musical/instruments have already been analyzed in past years on violins. The ‘‘virtual’’ instruments can be used in subjective listening tests for the evaluation of the sound quality of different instruments, as well as in the restoration of ancient instruments, and for preliminary listening tests on new designed instruments. In this paper, the trumpet is treated as a linear system, characterized by its impulse response. From the IRs measured in different positions in the trumpet, an inverse numeric filter of three trumpets has been obtained, through a new developed technique. From the recording of some original pieces of music, sampled directly inside one of the trumpets, an ‘‘anechoic’’ signal has been obtained by convolution with the inverse filter calculated in the same position. The ‘‘anechoic’’ signal, convolved with the IRs just measured in the other trumpets, produced a signal containing all the acoustic characteristics of the instruments, avoiding all nonacoustic phenom...

Music and sound of the 17th Century: Athanasius Kircher and his Phonosophia anacamptica

In the 17th Century many Physicists, Mathematicians and Musicians dealt with the experiences of harmony, music, and sound propagation in enclosed interior spaces. Among them, Athanasius Kircher was one of the most influential researchers of his time. Born in Geisa, Thuringia (Germany), he became a Jesuit in 1608 and spent a large part of his life in Rome, where he died in 1680. During his lifetime, he wrote several books spanning a wide range of topics, including sound, music, and acoustics. One of these, the Phonurgia Nova, published in 1673, was almost ignored for hundreds of years. Phonurgia Nova was translated from the original Latin. It consists of two different books, the Phonosophia nova and the Phonosophia anacamptica. The former deals with the influence of music on human beings whereas the latter analyses sound propagation in enclosed spaces. In this paper, the Authors present new achievements regarding some of the apparatuses that Kircher invented. Among all his marvelous sound machines, the Aut...

The Calculation of Energy Performance of Buildings with Summer Degrees

The energy performance of buildings (EPB) is usually calculated by reference to winter conditions. All standards, technical, normative and national laws consider building calculation of costs and energy performance during winter months. The energy performance of a building is related to outside temperature and comfortable inside temperature, therefore EPB depends on external weather trends. The “measure unit” of weather trends, used in some calculation models, is the Day Degree which represents the hours when the outside temperature is below the inside temperature standard. However, world climate changes and the diffusion of HVAC (Heating, Ventilation and Air Conditioning) systems, especially single-unit systems (split system), introduced the concept of comfort in the summer months and weather derivates - Hot Day Degree (HDD) and Cool Day Degree (CDD) used to establish weather risks for insurance purposes. HDD and CDD can be used to plan, check and evaluate energy performance before and after an energy project. To evaluate energy performance in a building in summer conditions we can use the studies on comfort perceptions to translate a Day Degree concept in “measured units” to evaluate with respect to a normalised cooling regime. In this article the outside temperature Summer Day Degree trend is proposed, within fixed temperature values (comfort range), humidity, wind velocity, and radiation incidence. Moreover, an example of how the Summer Day Degree can be applied is presented.

Acoustic quality in the Theatre ‘‘Palafenice,’’ Venice

The burning of the Teatro La Fenice, in Venice, has also been a tragedy for the acoustical community. The Municipality of Venice decided to build a tense‐structure (called PalaFenice) on the isle of Tronchetto, as a temporary auditorium for operas and concerts. The use of such a structure provokes many different acoustic problems, quite different from those already known to musicians at La Fenice. In this paper the acoustic quality of the theatre has been analyzed, and compared to the acoustic measurement already performed in the former La Fenice theatre. Binaural measurements have been performed in the hall using the impulse response technique (including absorption of the ceiling), and a dummy head located at different listening positions. According to ISO 3382, many acoustic parameters have been evaluated, like listening level, ITDG, reverberation time, IACC, and others, and their values have been mapped. Also, Ando’s quality maps of preferences, with reference to two different kinds of musical signals, was accomplished from experimental measurements. The measurements pointed out an unsuitable behavior of the structure at low frequency and low reverberation time and intelligibility in the hall. Finally, an hypothesis of the acoustic chamber has been formulated.

The sound quality of the Teatro Comunale in Treviso, Italy

The Teatro Comunale of Treviso was designed at the same time as the Teatro La Fenice of Venice, in the middle of the 19th century. Treviso being so close to Venice, the reputation of the Venetian Theatre, just rebuilt after the burning of 1836, influenced the municipality of this little town, which decided to design the Theatre with the same shape as la Fenice. After the burning of 1996, and following the disappointment of losing such unique architecture and sound quality, acoustical measurements were performed in many Italian theatres, especially in historic theatres where acoustical measurements were never before undertaken. In this paper, the results of the acoustic measurements are presented. According to ISO 3382, binaural measurements, with a dummy head, have been performed in 25 positions in the hall, with different positions of the sound source in the proscenium. Acoustical parameters, such as EDT, G, LE were calculated from the impulse responses and mapped. Also, Ando’s quality maps of preference...

Material and obsolescence on flute tone quality

The rule of material and obsolescence on flute tone quality has been discussed for a long time among musicians and flute makers. Mozart himself made use of crystal flutes in some of his works (Rondo’, K617, Adagio, K356). From an acoustical point of view, since Boehm’s work of 1832, the effect of material on flute tone quality has not been investigated, until researches of recent years [Coltman (1971); Chapuis (1991)]. In this work the research has been carried out measuring impulse responses inside the tube of the flute. Two different flutes have been utilized, i.e., a light‐alloy flute and a silver flute. The MLS sequences, with homemade software, have been utilized, gathering impulse responses in two different positions in the tube, in order to verify the variation of sound field. From the impulse responses a frequency analysis has been obtained, which pointed out that the silver flute contains more high frequency and shorter transient than the light‐alloy flute. Starting from the impulse responses, so...