Atatürk Kültür Merkezi Büyük Salonu'nun akustik açıdan performansının değerlendirilmesi

Abstract

Bu tez, Atatürk Kültür Merkezi Büyük Salonu'nün hacim akustiği kri¬ teri açısından performansının değerlendirilmesini içeren bir çalışmadır. Çalışmanın ikinci bölümünde, konunun anlaşılabilirliği açısından gerek¬ li tanımlar ele alınıp tanımlanmıştır. Konuyla ilgili temel bilgilerin aktarılmasına devam edildiği III. Bölüm¬ de akustik kalitesi sübjektif özellikleri açıklanmış ve bu özelliklere göre yapma sübjektif değerlendirme sonuçlarının nasıl sınırlandırıldığı anlatılmıştır. III. Bölüm kapsamında,- opera ve konser salonlarında akustik açıdan etkili olan faktörler, her iki salon çeşidi için ortak kısımları öncelikle açıklandıktan sonra, kendilerine özgü özellikleri aynı başlıklar ile ele alınarak açıklanmıştır. IV. Bölüm kapsamında, konuyla ilgili teorik ve deneysel yöntemler kı¬ saca anlatılmış ve karşılaştırılmıştır. V. Bölümde tez çalışmasının hedefi olan A. K. M. Büyük Salonu'nun hacim akustiği kriterleri açısından değerlendirilmesi ele alınmıştır. Bu hedefe yö¬ nelik ilk adım, salonun nitelik ve nicelik açısından tanımlanmasıdır. Daha sonra üç ayrı analiz yöntemi ile salonun değerlendirilmesine geçilmiştir. İlk yöntem olan Geometrik Analiz kapsamında önce salon içindeki yüzeylerin yansıtıcılık analizleri, daha sonra bu yüzeylerin yansıttıkları sesin doğrultularının analizleri ve son olarak da, salon içinde parter ve balkon katlarının her ikisinde rastgele seçilmiş koltukla¬ ra, etkin yansıtıcı elemanlar tarafından gönderilen sesin eko kontrolü yapılmıştır. IV. Bölümde yer alan teorik hesaplama yöntemlerinden Sabine Yöntemi kullanılarak, Büyük Salon'un merkez frekanslardaki reverberasyon süresi, opera ve konser durumu için ayrı ayrı hesaplanmıştır. Bu kısımda, ses yutuculuk katsayıla¬ rında, salonda büyük alana sahip iki unsur olan oturma elemanları ve asma tavana ait olanlar ikişer alternatifle değerlendirilmiştir. Bu nedenle dört alternatif sonuç elde edilmiştir. Üçüncü analiz, Büyük Salon opera ve konser düzenleri için seçilen al¬ ternatifleri ve sübjektif değerlendirmeleri içermektedir. Çalışmanın sonuç kısmında, IV. Bölümde yapılan teorik çalışmaların sonuçları değerlendirilmiştir. Bu kışıma ait bazı tablolar Ek A'da yer almaktadır.

in this thesis, öne of the most important hail of Türkiye, Grand Hail of Atatürk Culture Center is evaluated according to its acoustic performance in operas and concerts. in the first four chapters, the defınitions about the subject and the theoretical and experimental techniques that has been developed are simply described. (References to books and papers can be seen inside the texts.) in the second chapter, the properties of the sound, and its behaviour in enclosed spaces is described. The first section of the second chapter is about the defınitions essential for understanding the follovving chapters. Sound is the name given to the movements of particles of a sol id ör liquid which are propogated through the medium by reason of its elesticity and it is generated in a medium any process that causes a local movement in any part of the medium. The movement may be impulsive, consisting of a sudden displacement lasting only a short time, ör it may be periodic, consisting of a pattern of displacements indefınately repeated. The number of such repetitions in unit time is known as frequency of the sound. This frequency largely determines the sensation of musical pitch that is assoiciated with such periodic sounds. The wavelength of a frequency is; the distance a wave travels for öne cycle. The wavelength of sound in 20 -lOOOOHz is 17m - 25 mm. The relaitionship between frequency and wavelength is important in acoustical design of auditoriums. The second section of the second chapter describes the behaviour of sound in enclosed spaces. Those are; reflection, absorbtion, diffusion, reflection, reverberation and resonance of sound. The last section of the second chapter is about acoustical requirements and elimination of room acoustical defects which are echoes, focusing of sound coupled spaces, distortion inadequete diffusion, room rezonance, acoustical shadowing, whispering galleries and noise. in the third chapter, the subjective properties of Musical Acoustic Quality are; Intimacy; up to the initial time delay vi gap. Liveness which depend on the reverberation time at mid - frequencies. Warmth, the reverberation times at low frequencies, the loudness of direct and reverberant sound whieh effect the acoustical comfort of the audiance.Diffusion; which has importance in concert halis for the uniformity of sound. Balance blend and ensemble; which describes the relation betvveen the performers. The second section of the third chapter is about the Acoustical Evaluation of Concert Halis and Opera Houses. The general attributes both concert halis and opera houses are preliminary described. These are; the effects of volume and fıguration, kind of productions, designing factors according to the seating area. Then the design properties, private for operahouses, like orchestra pit are described with ör without stage and stage planning the acoustical attributes for concert halis are listed. The fourth chapter describes the theoretical and experimental studies about the subject. First, tthe theoretical studies, including the deşeriptions essential for the calculations and the two main methods; Sabine and Eyring, are present. The first section of the fourth chapter is ended with comparing the methods. The second section describes the experimental studies about the subject. This section stars with the standarts about measuring reverberation times in auditoriums. Next, some methods using for measuring the reverberation time is defined. The last defination from third chapter concerns the Measurment of Sound Pressure Level. in the fourth chapter, the acoustical evahıation of the Grand Hail from Ata-türk Culture Center is carried out, relating to the basic knowledge given in the second and third chapters. The Grand Hail of Atatürk Culture Center was chosen as the subject of this thesis because of its importance in İstanbul 's culturel life, and inere are many reasons for this. First of ali, its located in the center of İstanbul very near to other culturel activities, and it is used so frequently that; it is hardly empty and without an action. its seating and the stage capacity let the b iğ productions of operas, ballets and symphonic concerts take place in the Grand Hail. If Atatürk Culture Center as a whole is described, the Grand Hail 's importance and its place in culturel organizations can easily be understood. in the early 1930 's it had been realized that; a large hail was essential for the culturel capital of Turkey, and the first step for this purpose was taken by organi-zing an international design competition. The expectations from the design was an opera house j üst like the ones in Europe, instead of a multi-purpose culture center. But it was impossible for the \yinning project to be built because of the economical circumstances of the World War II. After a long period of time, the construction was started in the consultation of the Architect Prof. Dr. Hayati Tabanlıoğlu and fınally in 1969, it was completed and opened as"Culturel Palace ". But öne year after the opening, the Grand Hail and the stage was destroyed by the fire. Then a restoration program was undertaken, and the building was opened again in 1978 with the new name: Atatürk Culture Center. Being öne of the biggest culturel complexes of Türkiye, the Center includes the Grand Hail providing 1317 seats, the Concert Hail with the capacity of 530, the Chamber Theater with 215 seats, the Chamber Cinema with 275 seats and the exhibition halis. The Grand Hail includes two balconies över the main floor and it is symmetrical in centerline. Its plan shape looks like a horse-shoe plan which is common for opera houses. But the circularity of the typical horse-shoe plan can not be seen here. Highly diffusive side wall surfaces, extending from nearly 2.5 m.above the side aisles to the ceiling, provide strong lateral reflectors. They have a triangular section empty inside and constructed of 2 cm.of plywood över airspace. The aisles' walls are covered with 0.6 cm.of ceramics 15x15 cm. in size. Each side of the symmetrical plan has 4 entrance doorways in the main floor and öne for each balcony which makes totally 12 doors mat are treated to be highly absorptive inside the hail. The ceiling of the aisles are plastered. The back walls are designed to be highly absorptive and tipped in at the top abaut a certain degree so that the reflections (if ocuured) can be directed to the audience seated at the rear part of the hail. This treatment is useful for echo- control from the rear wall. For the floors; the carpeting was placed in the aisles only and linoleum was used under the seats. Both of the materials were applied directly to the concrete floor without any extra treatments. Under the balconies, suspended ceiling made from painted plywood is used but the front parts are plastered över the construction of the balconies. The ceiling of the hail is suspended to the construction by means of steel profiles. The material used for the ceiling is made from aluminium sheets in the shape of triangular pyramids, and stepped to lower to both front and the sides of the hail. The ceiling which covers a great area, was designed to help the diffusion of sound in the hail and it plays a great role in this. There is a huge panel suspended at the very front part of the ceiling of the hail vvhich covers mostly the proscenium stage, made from plyvvood and has a great affect on useful reflections from stage to the main floor and the balconies. viii The stage consists of 6 movable platforms giving the opportunity of different design facilities to productions and let the orchestra pit become a proscenium stage when necessary. The material for the stage floor finish is thick wood on battens. The panels on each side of the proscenium stage reflects sound to audience and made from 2 cm. plywood over air space. Before starting the evaluation of the Grand Hall in steps, the numerical and physical attributes of the hall is given, using tables and figures. The evaluation can be defined by using three methods supporting each other. Geometrical analysis method is basically used for determining the attributes of the reflections from the surfaces and controlling if acoustical defects like echoes exist in the hall or not. This approach considers the acoustical problem in a similar way to optics, but more rigorous approach called Physical Acoustics is used to determinate the reverberation characteristics of the hall. The existing reverberation time in fundamental frequancies for the hall is calculated in this section. The numerical attributes of the Grand Hall is defined for both opera and concert situations. The third method; which is not considered in the evaluation, deal with small studies such as those generally used for speech programmes in a different manner because the dimensions are usually small when compared with the wavelegths of the sound. This method is not used in the evaluation of the Atatürk Cultural Center's Grand Hall because it is not considered in the large spaces as the dimensions are hardly problem when compared with the wavelengths. The acoustical evaluation of the Grand Hall starts with using the geometrical approach. This approach consists of three steps. Those are;. Analysing of the reflectivity of the surfaces of the hall is done by comparing the shortest dimension of each surface with the wavelengths of the standards frequencies. The results are presented in the Tables 4. 1 (a- f ). The reflection analyses of the surfaces according to direction is carried out in the plans and sections of the Grand Hall by drawing sound rays from the stage is either position of the sound source (both for opera and concert situations) to yhe audiance. So; which surface reflects sound to audiance and how many of them are succesful in reflecting sound can be seen. This process is applied to all of the plans and the sections.. The echo control or long delay reflection controls are made on the illustrations of the Grand Hall by choosings points from the audiance area randomly. This control is made on the main floor, the two balconies and the sections. The results; which describes the time delay between the direct sound and the first reflection in miliseconds. These are shown in tables. IX The statiscal approach to the acoustical evaluation of the Grand Hall is necassary for calculating the reverberation time for standard frequencies. This can be carried but by using either Sabine's or Eyring's methods which are described in third chapter. In this thesis, Sabine's formula for calculating the reverberation times is choosen, as it is more convenient and equally viable to use for lightly damped enclosures. Eyring formula should, therefore, be used for all enclosures with a high average absorbtion coefficient, for example; some special studies. Before starting the calculation of the reverberation time for the Grand Hall, the materials used on the surfaces are described in the tables by using photos, illutrations and sound absorbtion coefficients. The sound absorption coefficients of these materials are choosen from the tables in the acoustical literature but two of the surfaces which covers a great area in the hall are taken with two alternative coefficients for each. And the following calculations were made according to for combinations of these coefficients. So, the calculations are ended with four alternatives of results. Selecting the coefficients from the literature was carried out with giving care to the similarities between the materials used in the hall and the materials described in the literature. Prefering one of the resulting alternatives is difficult as no criteria was found, like measurements to check the results. But through the opinions of the opera singers and the musicians one of the results seem to have true values. Subjective evaluation of the hall, carried out in references to second chapter, by using the prefered resultant reverberation time and opinions of the opera singers and musicians, was ended with cathegorizing. The results, as descibed for the Grand Hall of Atatürk Cultural Center, is not sufficent in acoustical performance, mostly for opera pruductions. Since the main acoustical deficiency in the Hall result from the surfaces near and in the stage both in Geometrical Analyses of the surfaces near the stage (the panels on both sides of the stage and the huge panel over proscenium and the orchestra pit) and through the general idea of the opera singers, it can easily be seen that theese surfaces are not sufficient to send the useful reflections to the audiance and more reflective surfaces are needed in the stage house so as to help the singers' performances.