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v3.0, 20040325, ME

Session Z6 Monday, May 10 09:30 h–11:00 h
Posters: Room and Architectural Acoustics & Musical Acoustics

Room and Architectural Acoustics
Adaptive Room Equalization in the Frequency DomainJorge Leitao1, Gabriel Fernandes2, Aníbal Ferreira1,3
INESC Porto, Porto, Portugal
DEEC, FCTUC, Coimbra, Portugal
3 FEUP, Porto, Portugal
This paper addresses the implementation of a real-time 20-band adaptive digital audio equalizer for room equalization. The system has been implemented on a TMS320C6711 DSP platform and performs adaptive filtering using techniques of fast filtering in the frequency domain that include an adaptation procedure. The paper explains how the structure of a previously designed graphic equalizer has been improved to support adaptivity, describes its operation as well as its functionality based on a graphical user interface, and presents the results of tests that have been conducted to optimize its performance.
Z6-2 Acoustic Reconstruction of Buildings in the Ancient City of OlympiaStamatis Vassilantonopoulos, John Mourjopoulos, Univeristy of Patras, Patras, Greece
Virtual acoustics can assist the aural exploration and the study of the acoustic properties of famous buildings of antiquity. Here, examples of such reconstruction of ritual and public buildings of the ancient Greek city of Olympia are presented, and findings of their acoustic behavior are introduced, especially with respect to the modes of speech communication and general functionality. Examples of these auralizations are presented and are made available in an electronic address.
Z6-3 A Software Application for Estimation of Room Acoustic Behavior by Multisource Excitation—Athanassios Fouloulis, Christos Goussios, Charalambos Dimoulas, George Kalliris, George Papanikolaou, Aristotle University of Thessaloniki, Thessaloniki, Greece
The purpose of this paper is the design and implementation of a software application for the estimation of the acoustic behavior of a rectangular room when a number of sound sources are activated. The room dimensions, the number, and positions of the sources can be selected. Materials are chosen from a library. Sound level distribution is calculated for a desired section of the room, using the image source method. Room modes are calculated for studying the standing waves. Reverberation times are also calculated using statistical formulas. Work has been done for the use of this software in nonrectangular rooms, based on different estimation methods.
Z6-4 The Acoustics of Ancient Greek Odea—Christos Goussios, Christos Sevastiadis, George Kalliris, George Papanikolaou, Aristotle University of Thessaloniki, Thessaloniki, Greece
Apart from the world famous ancient Greek theaters, whose acoustics often attract engineers, smaller closed amphitheatric halls—called odea (plural of the Greek word odeion)—had been constructed and used through the Greek and Roman periods. The acoustical characteristics for most of them and information concerning their location, use, history, and architectural elements are presented. An attempt was made for the modeling and estimation of their acoustics. Results of measurements also carried out are discussed.
Z6-5 On the Acoustics of Old Berlin Studios for Film and RadioErnst-Jo. Voelker, Institute for Acoustic and Building Physics
A certain acoustical environment was always necessary when sound of adequate quality had to reach the audience. That applied both for natural sound and for sound reproduction via loudspeakers by using electrical or mechanical amplification. Long before microphones, amplifiers, and loudspeakers were developed and used; studios in the form of “Glasshouses” were built (e.g., in 1911 in the City of Babelsberg near Berlin), using bright and wide sunlight. For sound recordings, huge horns were connected with wax-plates or wax-cylinders. Sound had to be absorbed by curtains, carpets, and much plush, which was already well known since the first stereophonic transmission during the First Electrical Fair in Paris in 1879. Radio started in the twentieth century, in Berlin, with the Eugin Reiß carbone microphone in an almost over-damped studio on October 29, 1923. Some years later a “Haus des Rundfunks” was opened with many studios of different use and quality including a concert hall. Film and radio went their own ways with multichannel reproduction or, for long time, only with mono transmission. Some acoustical aspects of the first studios will be described.

Musical Acoustics
MPEG-7-Based Low-Level Descriptor Effectiveness in the Automatic Musical Sound Classification—Piotr Szczuko, Piotr Dalka, Marcin Dabrowski, Bozena Kostek, Gdansk University of Technology, Gdansk, Poland
The objective of this paper is to determine which of the MPEG-7 standard low-level sound descriptors are most significant in the process of automatic classification of musical instrument sounds. First, pitch detection is performed. Then, the parametrization stage of musical sounds based on descriptors contained in the MPEG-7 standard is carried out. Next, a thorough statistical analysis of the feature vectors obtained is performed. For the purpose of automatic classification two decision systems, based on artificial neural networks (ANNs) and rough sets, are used. Both decision systems are trained with feature vectors consisting mostly of parameters contained in the MPEG-7 standard, however, their content is reduced after statistical analysis. In addition, a comparison of results obtained by these decision systems with the results derived from the nearest neighbor algorithm is made.
Z6-7 Scale Degree Profiles from Audio Investigated with Machine Learning Techniques—Hendrik Purwins1, Benjamin Blankertz2, Guido Dornhege2,, Klaus Obermayer1
Berlin University of Technology, Berlin, Germany
Fraunhofer FIRST (IDA), Berlin, Germany;
In this paper we introduce and explore a method for extracting low dimensional features from digitized recordings of music performance. The so-called constant Q scale degree profiles are 12-dimensional vectors that reflect the prominence of the 12-scale degrees in respective analyzed parts of music. Here we study the type and amount of information that is captured in those profiles when calculated from whole short pieces of piano music. The analyzed data set includes pieces from Bach’s Well-Tempered Clavier (WTC), part I and II, the sets of preludes that encompass a piece in every key by Chopin (op. 28), Alkan (op. 31), Scriabin (op. 11), Shostakovich (op. 34), and the fugues of Hindemith’s “ludus tonalis” (one fugue for each pitch class, neither major nor minor). For the purpose of investigation we employ supervised and unsupervised machine learning techniques. In a supervised approach we investigated the ability of classifiers to recognize composers from profiles. As unsupervised methods we performed (1) cluster analysis which resulted in one major and one minor cluster, and (2) a visualization technique called Isomap which reveals in its 2-dimensional representation some additional structure apart from the major-minor duality. In summary it is astonishing how much information on a music piece is contained in the 12-dimensional profiles that can be calculated in a straight-forward manner from any digitized music recording.
Z6-8 Automatic Estimation of Reverberation Time—José Vieira, Universidade de Aveiro, Aveiro, Portugal
The correct estimation of the reverberation time of the room acoustics can be an important task for several systems such as sound localizers, hearing-aids, and telephony. These systems are affected by reverberation and need an estimate of this acoustic parameter in order to adapt the algorithms to different environments. This paper presents a method to estimate the reverberation time of a room without using test signals. From the captured signals in the room, the system is able to estimate the reverberation time without any prior knowledge of the sound sources or room geometry. The estimates are obtained from the “tails” of the sounds, and we use a run-length energy integral followed by an algorithm that estimates the decay of the sound energy.

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