Ανακοινώσεις σε Διεθνή Συνέδρια

Although the acoustical design of classical auditoria has been the object of thorough investigation over the past decades, the acoustical design of jazz auditoria has hardly been the object of scientific research. In one of the fewest works recently published, the optimal reverberation time has been explored through laboratory experiments; a mean optimal value has been proposed at 0.8 s. Nevertheless, the question of optimal spectrum balance for jazz venues, still remains to be answered. This apparently, is important particularly in determining construction detailing. The objective of the present work is to explore the optimal spectral balance for the acoustics of Jazz clubs. This is an experimental study which involves synthetic sound fields through headphones. Music experts were asked to evaluate four jazz excerpts with and without wind instruments. The aim was to evaluate the optimal spectral content of these excerpts, for each of three independent subjective acoustic factors that had been experimentally derived in an earlier study. These factors were Clarity, Tonal Quality and (aural) Proximity. Unlike classical and rock concerts, jazz auditoria were found to require a flat frequency content for music ensembles without any wind instrument. Nevertheless, in the case of solo wind instrument, the preferred spectrum involved; on the one hand, an increase in bass relative to mid frequencies by 1,6/1,0 and on the other hand, a considerable increase in treble relative to mid frequencies by 1,8/1,0. Furthermore, in the case of ensemble including any wind instrument, the preferred spectrum involved an increase in treble relative to mid frequencies by 1,5/1,0. All the above results were found to be independent of each of the three distinct subjective factors tested. A detailed Discussion is made. More research is called for to confirm the present results for a wider range of jazz repertoire in the live concert situation.

This paper is part of a larger project aiming to review Hellenic drama theatres and their acoustical performance in relation to their architecture. Acoustic measurements were performed in six theatres in and around Athens, ranging from 19th century neoclassicism to 20th century post war modernity. Results indicate that: Basic differences in the acoustical performance between auditoria of period architecture and post war modern theatres refer to the room size. Building elements and features such as small distances from stage etc., were identified as potential contributors to good acoustics regardless of architectural period/style. The present findings confirm results from earlier studies, they cast some light on the implications of integrated acoustic design in the architecture of drama theatres and demonstrate, by and large, acoustical merits of the test auditoria.

Relationships between physical acoustic parameters and stage design variables were investigated using computer simulation. This is amongst the fewest studies which use such an approach and it is the first study which employs an existing source auditorium. The latter is a reputable chamber music auditorium. Two stage acoustics parameters were tested, namely the STearly and the STlate. Five stage design variables were employed in the experiments, namely stage width, splay of side walls, stage height, canopy tilt and tilt of back wall. For each design variable five to eight stage configurations were tested. Stage design characteristics were identified which satisfy the selected acoustics parameters. The present study casts some light on the understanding of stage acoustics design in small auditoria.

Subjective acoustic evaluation experiments were carried out for the first time using modern psychometric methods, in small Rock auditoria in Athens employing ordinary Rock concert goers. Factor analysis of the raw scale judgements produced two independent subjective Factors, namely BODY / LIVENESS (pleasant, preferred, full bodied) and HARSHNESS (sharp, rough, harsh). Relationships between subjective Factors and physical measurements identified the subjective significance of distance from stage and of the low frequency Reverberation Time. The latter is in agreement with earlier studies. These results shed some light on the question of good acoustics, as perceived at live Rock concerts by a wide cross-section of Rock concert goers

Acoustical measurements were carried out in Athens in orthodox churches of the modern Greek period. Two distinct groups were identified, i.e. those churches which belong to the 19th and early 20th century and the relatively recent churches. The first group exhibited, by and large, relatively acceptable acoustic performance thanks to the structural materials and building techniques employed. In the other group, there were identified excessive uninterrupted church volumes which, combined with extensive reflecting boundaries, impaired the acoustical performance. All churches were found to be poorly protected against noise. Comparison of results with the acoustics of (historical) Byzantine churches, demonstrates that there is a lot that present-days churches need to adjust in order to emulate their archetypes. The present results cast some light on the understanding of design needs for acoustically effective churches in modern Christian orthodox societies.

Orthodox churches of the modern Hellenic period, i.e. since the independence of Hellenic nation in early 19th century, are replicas of (historic) Byzantine temples, though, normally of much larger scale than their archetypes, in order to accommodate the increasing population of church-goers in modern societies. This sort of churches have highly reflecting inner boundaries such as their archetypes, whilst the well known tradition of iconography is conspicuous on their inside envelop. As a result, spare surfaces to host any sound absorptive treatment are limited. Under such circumstances, reverberation, could not be anything but excessive. With the aim to study this situation, measurements of reverberation time were carried out in Athens in twelve churches; the latter, were so selected as to be representative of the Orthodox church of the modern Hellenic period.

Two distinct groups of churches were identified from the analysis. Namely those that belong to 19th and early 20th century, which were found to have reasonable reverberation. By contrast the remaining churches which are relatively recent, exhibited excessive reverberation despite the fact that the two groups of churches have comparable volumes with each other, and their inner boundaries are hard and reflective. An explanation to this finding has been seen in the concept of church boundaries ‘complexity’ and its connection with total room absorption and reverberation. The present findings a) cast some light on the question of excessive reverberation in present days Orthodox churches, and b) provide a challenge for the architect to experiment with new forms that can improve acoustical quality, in contemporary Orthodox churches.

Mediterranean architectural heritage comprises classical auditoria of universally acknowledged acoustics, such as Hellenic ancient theatres, Byzantine temples, etc. Despite their natural sound been widely acclaimed, recently there has been a trend for such spaces to employ electronic amplification of their natural sound. The present work is a pilot study; this aims to investigate experimentally, whether natural acoustic properties of such auditoria can be enhanced by the use of electroacoustic amplification or, on the contrary, the latter will result in degradation of the overall acoustic experience. This study involves two subjective acoustic evaluation experiments in which two distinct monuments were used; one was a typical Hellenic Christian Orthodox church; the other monument was one of the most exemplary Mediterranean ancient theatres, namely the ancient theatre of Epidaurus. Ordinary audience as well as theatre experts were employed in the evaluations. Amongst other methods semantic differentiation was also used in the experiments. It is demonstrated in both experiments that the majority of respondents prefer performances without microphones. In one of the two experiments, namely in Christian Orthodox church it was made possible, further, to demonstrate that electroacoustic amplification, despite supporting subjective sound strength, this is at the expense of the overall acoustic experience. There is evidence, that environmental noise pollution is significant drawback in both cases tested; therefore, the dilemma is revisited, about use of microphones in the test auditoria. Based on present findings, it could be argued that electroacoustic amplification in classical auditoria of universally acknowledged acoustics, could not be rejected a priori. However, as with any other artistic tool, electroacoustic amplification in such auditoria needs be approached with care, since this may impregnate hazardous irreversible situations.

Neoclassicism was established and dominated in Greece in the second half of the 19th century. At that time, several neoclassical public buildings were built, including lecture halls, such as the ex-Royal Palace (now the building of the Greek Parliament), the Averof building of the National Technical University of Athens, the University of Athens, etc. The lecture halls of this category are distinguished for the quality of their proportions, the correct scale, the gentle style and the sculptural and not only décor. However, there is a common flaw, which is the problematic acoustics of the rooms. This is related to the architectural choices of the rooms that systematically ignore the rules of acoustic design, since, admittedly, architectural acoustics became a science much later, i.e just at the turn of the 19th century. What exacerbates the problem is that the possibility for remedial acoustic design of the rooms is extremely limited due to the necessity of preserving / respecting their historical character. This study uses four examples of neoclassical auidtoria, namely the Kaftantzoglou Hall of the Averof Building of the National Technical University of Athens1 , theCeremonial Hall and the Eastern Hall of the Academy of Athens, as well as the Hall of the Greek Parliament. Based on acoustic measurements in situ, problems, and solutions that were adopted in order to correct their acoustics, are presented and commented on. 

The theatres of Antiquity, Greek and Roman, constitute public buildings of the utmost importance in the history of Western culture and in universal cultural heritage. Many of these spaces are being used for their original function with or without only minor adaptations. If they are well preserved and/or restored, these performance buildings attract large audiences to representations of classical and contemporary plays, thereby serving the purpose for which they were built in the Ancient Age. These theatres bear witness to the existing relationship between architectural work, visual and acoustic experience, and dramatic art. After Oiniades theatre acoustic assessment, published in 2003, Epidauros theatre and Dionysian theatre in Athens, followed. Present paper is about the acoustic assessment of Argos theatre in Argolis Peloponnesus Greece. Argos ancient theatre has unusual geometry carved in rock. It has a capacity of 20000 spectators and presents a lot of challenges for its assessment.

First, some measurements were taken on the spot, which were then introduced into Dirac and Matlab softwares in order to produce information regarding reverberation time, spectral properties and speech intelligibility. Furthermore, a digital model of the theatre was set up, which was then introduced into EASE software where simulation took place. In this way it was made possible to determine if the initial measurements match the simulation results, therefore the acoustical properties of ancient theatres can be digitally modeled.

This is an educational project which is going to be implemented in a city of music tradition, -namely Wieliczka. The New Opera House was conceived to function as a music and cultural center of the entire community and was designed to create functional indoor and outdoor space. The development extends over 36300 m2 on six floors and comprises a lyric theatre of 1100 seats with ancillary spaces such as dressing rooms, workshops, storage, etc., a black-box theatre, a multi-use space for meetings lectures etc., library, reading room, exhibition open space, rehearsal rooms, music teaching facilities, restaurant, and a large underground parking.

The auditorium is an evolution of the baroque theatre type and its volume, including the loft of the fly tower, becomes pivotal in the overall synthesis. The architect’s intention is to create a sculptural form so as to embrace the auditorium around in a spiral way, as well as to connect with the city by sloping downwards towards ground level. From this point the building becomes easily accessible by the average civilian who can roam around and be immersed into the spirit of the cultural monument. 

An overview will be made of the overall architectural design of the development. Furthermore, the acoustical design of the lyric theatre will be analyzed. The aim will be to illustrate the philosophy behind; namely, that although acoustics is based on objective design principles, the way the latter are translated into architectural language is unique for each auditorium, and depends on the cultural background and aesthetic point of view of the architect.

The study introduces the New Academy of Music, an educational project set to be implemented in Kifissia, Athens. Envisioned as a hub for the community, the academy is designed with spaces that are functional, encompassing both indoor and outdoor areas. The proposed solution comprises two zones, namely, a public one where musical and cultural activities are hosted, and a more private zone dedicated to instruction/tutoring activities as well as administrative functions. The teaching zone consists of small and large classrooms for musical instruments, theoretical courses, percussion instruments, group classes, orchestra, choir, and studios for rehearsal and recordings. The cultural zone includes a chamber music auditorium of 350 seats, foyer, dressing rooms, an exhibition room, a small amateur radio station, and an outdoor multipurpose theatre for 550 persons. An open air cafeteria functions as a conceivable boundary between the two zones.

This study investigates the optimal reverberation time (RT) for jazz concert venues through an experimental approach. While most research on auditorium acoustics has focused on classical music, jazz music requires distinct acoustic considerations due to its unique sonic characteristics. Twenty-nine music experts evaluated four anechoic jazz excerpts, including solo and ensemble performances with both string and wind instruments, presented through headphones in controlled conditions. Participants adjusted the RT of a virtual sound field to optimize listening for three subjective factors: Clarity, Tonal Quality, and Proximity. Results indicated two distinct optimal RT ranges: 0.60 s for non-wind instrument ensembles and 0.85 s for ensembles including wind instruments. These values were consistent across the three subjective factors. The findings suggest that small, acoustically absorptive venues are suitable for jazz performances and provide practical design guidance for future jazz auditoria.

The scope of this study is to investigate flanking noise transmission through joints between prefabricated concrete elements in School buildings; such joints apparently are not found in the wholesome structure of ordinary concrete buildings. Sound insulation measurements in a prefabricated concrete building of the cell type, were carried out in Athens. This type of prefabrication involves demountable/reusable concrete elements (the cells), which makes critical the question of flanking noise transmission at joints. A sample of seven dividing partitions of classrooms were tested. Sound insulation was also predicted using classical prediction model. Analysis of the measured data leads to useful results about the field acoustic performance of prefabricated concrete wall partitions. The importance of meticulous sealing at joints is also demonstrated.

This is part of an educational project which is going to be implemented in central Athens. The development involves, amongst other spaces, a multipurpose auditorium of high acoustic flexibility which seats a maximum of 350 persons. Acoustic flexibility is achieved thanks to variableacoustics modules which are built in the room boundaries including the ceiling. Example room configurations are employed and predictions of acoustic parameters are made to demonstrate the efficiency of the room’s variability. The high flexibility of the auditorium is considered to be a firm basis for music-acoustics-architectural experimentation, which is the target of the present study.

The present study comprises subjective acoustic evaluation experiment, using auralised Byzantine chant, and refers for the first time to orthodox churches of modern Greek period. Ordinary church goers made their evaluations through headphones, on bipolar semantic rating scales. Factor analysis of the raw scale judgments produced three independent subjective factors, namely DISTINCTNESS / PREFERENCE (“distinct - non distinct”, “preferred - non preferred”, “pleasant - unpleasant”), DEPTH / FULLNESS (“shallow - deep”, “long - short”), and SUBJECTIVE INTENSITY (“intense - calm”, “live - dead”). The factors explain a fair percentage (52%) of the total variance of subjective data. These results, by and large, confirm earlier findings from acoustic evaluations with live Byzantine liturgy. The present results illuminate some of the ways, ordinary church goers describe their acoustic experience of listening to Byzantine chant. 

“Kaftantzoglou” auditorium is a neoclassical monumental venue, over hundred years old; also the building is a Europa Nostra award winner of year 2012. This auditorium is used for multi purposes with emphasis on lectures. The hall has excessive volume relative to its capacity (33m3/seat) which apparently is associated with excessive reverberation time. In addition the hall has extended curved surfaces which are responsible for the production of detrimental echoes, focusing of sound, flutter echoes, etc. A major limitation for remedial acoustics is that the monumental size and character of the venue must be preserved. The acoustic design was based on physical measurements in situ, and in virtual space using the “Odeon” software. This project is indicative of the difficulties and limitations involved in the acoustic remedy of venues such as the present auditorium.

Subjective evaluation experiments of stage acoustics were carried out in six Jazz auditoria in Athens during live concerts. Semantic rating scales of the bipolar type were used in the evaluations; Factor analysis of the raw scale judgments produced three independent subjective factors, namely PERCEIVED REVERBERATION – NOISINESS (“noisy – clear”, “reverberant – non reverberant”), LIVENESS – BRILLIANCE (“live – dead”, “dark – brilliant”) and SMOOTHNESS (“smooth – harsh”, “smooth – sharp”).  Present results, for the first time, cast some light on the question of number and identity of independent subjective qualities of stage acoustics, using scientific methodology. These results illuminate some of the ways musicians describe their acoustic experience of performing in Jazz venues.

Subjective acoustic evaluation experiments were carried out at live concerts in four rock music halls in Athens, using, for the first time, the modern psychometric approach and ordinary concert goers. Bipolar semantic rating scales were employed in the evaluations. Factor analysis of the raw scale judgments produced four independent subjective factors, namely LIVENESS [“full bodied”, “coloured”, “live”], CLARITY [“smooth (-screechy)”, “smooth (-rough)”, “clear (-blurred)’’], HARSHNESS [“harsh”, “loud”, “sharp”], and BRILLIANCE [“high pitched”, “brilliant”]. The factors LIVENESS and CLARITY were relatively strong, and dominated overall acoustic preference and pleasantness. Some of the factors produced, were acoustic qualities distinct in rock music evaluations, whereas other factors were common to a range of different music genres. This work, illuminates some of the ways a wide cross section of rock concert goers describe their acoustic experience of listening to rock music. The importance of separate acoustic design for rock music auditoria is confirmed.

Subjective acoustic evaluation experiments were carried out at live concerts, employing two groups of assessors, each of distinct cultural background. Bipolar semantic rating scales were used in the experiments which were derived from a previous experimental study that employed recorded jazz music. Factor analysis of the raw scale judgments produced a number of independent subjective factors. Comparison of factor results between the two experimental groups demonstrated no significant differences between each other. The present results illuminate some of the ways a wide cross section of jazz concert goers describe their acoustic experience of listening to this genre of music, under the complexity of the live concert condition. General agreement of the present results with results from earlier studies employing either recorded jazz music or classical music live or recorded, supports the view that there are independent subjective qualities common to a range of music genres live or recorded.

Subjective acoustic evaluation experiments were carried out using commercial recordings of Jazz as well as ordinary Jazz club goers as assessors. The experiments involved first the development by experimental means of a list of opposite labels as descriptors of the acoustics of Jazz auditoria. These labels were then used at the poles of bipolar semantic rating scales in a number of subjective acoustic evaluation experiments through the internet. Factor analysis of the raw scale judgments produced four independent subjective factors, namely, TONAL QUALITY (smooth, gentle, velvety), CLARITY (clear, brilliant, crystal), BODY (rich, live, full bodied), and PROXIMITY (near, close). These results illuminate some of the ways a wide cross section of Jazz club goers describe their acoustic experience of listening to this genre of music. General agreement of the factors TONAL QUALITY, CLARITY and BODY, with results from earlier studies concerning either the sound of classical music or single sounds of music, supports the view that these are independent subjective qualities common to a range of music genres and to single music sounds.