Alban Bassuet

Computational and Optimization Design in Geometric Acoustics

The use of 3D computer modeling tools through the 90s has revolutionized the practice of architecture. Coupled with new fabrication processes, these have introduced new territories for architectural design. Such techniques are also available to acoustic designers for the shaping of spaces. With 3D modeling programs such as Rhino3D and Grasshopper incorporating NURBS, geometries can be easily adjusted to meet both aesthetic and functional objectives. Control points of NURBS elements give access to the parameterization of geometries which subsequently can be assigned variables and open the way to computational design optimization. Through several performing arts project examples, this paper gives an overview of processes used today by acousticians to refine designs either through iterative design, auralization, optimization algorithms and real-time computer modeling. Contextualized with design practices from different periods of history, the paper discusses the relevance of computational and optimization tools in the design process of shaping rooms, walls and reflectors and how these methods can support creativity, accelerate solution finding, and interface with complex architectural ideas.

New Acoustical Parameters and Visualization Techniques to Analyze the Spatial Distribution of Sound in Music Spaces

An important factor in our appreciation of music in a hall is the perception of the spatial distribution of sound, influenced by room shape and form. This paper investigates new techniques for visualizing 3D impulse responses and two new spatial indicators are proposed: LH (ratio of low lateral versus high lateral energy), FR (ratio of front lateral versus rear lateral energy). Different room shape characteristics are illustrated from B-format measurements conducted in a selection of famous music spaces such as old and new recital and concert halls, and sacred music spaces.

New implementation of multi-microphone recording technique to simulate music ensembles in room acoustic auralizations

This paper describes a method to record large musical ensembles for use in computer simulations and auralization. The method uses a multi-microphone hemispherical array distributed over an orchestra playing on a hard floor. A ray tracing program models the orchestra as sectors of a hemisphere corresponding to each microphone location. Microphone signals are then mapped to their respective source sectors by convolution with the models outputs. The method permits recording and simulating an entire orchestra with its directivity, including the movement of the musicians while playing. The approach is geared towards achieving a high quality of orchestral musicianship and sense of orchestral ensemble while maintaining high spatial accuracy and quality of timbre while also minimizing recording artifacts such as proximity effect. The method has been implemented with renowned performers and orchestras, and has been used in the auralization of several new concert hall design projects.

Concert Hall Design—Present Practices

Leo L. Beranek1, Anders Christian Gade2, Alban Bassuet3, Lawrence Kirkegaard4, Harold Marshall5 and Yasuhisa Toyota6 1BBN(Now Acentech), Cambridge USA; 2Gade & Mortensen Akustik, Denmark; 3Arup Acoustics, New York; 4Kirkegaard Assoc., Chicago; 5Marshall Day Acoustics, Auckland; 6Nagata Acoustics, Los Angeles. Emailberanekleo@ieee.org, acg@gade-mortensen.dk, alban.bassuet@arup.com, lkirkegaard@kirkegaard.com, harold.marshall@ihug.co.nz and toyota@nagata.co.jp

From the sound up: Reverse-engineering room shapes from sound signatures

Typically, architects and acousticians design rooms for music starting from a model room shape known from past experience to perform well acoustically. We reverse the typical design process by using a model sound signature to generate room shapes. Our method builds off previous research on reconstructing room shapes from recorded impulse responses, but takes an instrumental, design-oriented approach. We demonstrate how an abstract sound signature constructed in a hybrid image source-statistical acoustical simulator can be translated into a room shape with the aid of a parametric design interface. As a proof of concept, we present a study in which we generated a series of room shapes from the same sound signature, analyzed them with commercially available room acoustic software, and found objective parameters for comparable receiver positions between shapes to be within just-noticeable-difference ranges of each other.

Semi-anechoic music recording using multi-microphone technique to simulate orchestra directivity in room acoustic auralizations

Over the last two decades, computer generated auralizations have become increasingly relevant to the design process of new performance spaces. Auralizations are based on anechoic material, and simulation realism is often limited by a small repertoire of recordings and the challenges of simulating an orchestra’s complex sound radiation characteristics. To address some of these issues, this paper describes a method to record—in semi-anechoic conditions—large musical ensembles for use in computer simulations. The method uses a multi-microphone hemispherical array distributed over an orchestra playing on a hard floor. A ray-tracing program models the orchestra as sectors of a hemisphere corresponding to each microphone location. Microphone signals are then mapped to their respective source sector. The method permits to record and simulate an entire orchestra with its directivity, including the movement of the musicians while playing. The paper describes the influence of the radius and angular resolution of the microphone array; it also investigates different source configurations in the computer model. The method has been implemented with renowned performers and orchestras and has been used for auralizations of several new concert hall design projects.

The Acoustical Design of the New National Opera House of Greece

Scheduled to open in 2015 in the city of Athens the Stavros Niarchos Foundation Cultural Center will become the new home for the Greek National Opera and Ballet. This paper presents the acoustical design considerations for the future opera theatre. A retrospective of Greek influence in the history of the opera theatre design is presented with benchmarking and precedents considered for the project. Through presentations of the some of the design thoughts and approaches still in development, including the form, geometry, seating distribution, wall shaping, and materials in the opera theatre, the paper describes how the new design references and incorporates the profound influence of Greek Culture on development of the Opera House as we know it today.