9:00 am

P-1 Directional Radiation Characteristics of Articulating Line-Array Loudspeaker Systems

Mark E. Engebretson, Mark S. Ureda and Douglas J. Button, JBL Professional, Northridge, CA, USA

Directional radiation characteristics of a new form of line array-the articulating line array-are examined. Based upon a single three-way, horizontally symmetrical loudspeaker with variable unit-to-unit vertical splay angles, these components are capable of being configured into straight-line arrays, uniformly and non-uniformly curved arc arrays, progressive arc and J-form arrays. A unique system of suspension hardware provides a continuous baffle surface, and results in rigid array structures that can be flown in any attitude, from one or two points, as required. This paper compares calculated polar responses and polar measurements for various examples of each array type. Conformance between the calculated and measured performance serves to validate the predictive model, confirming the configuration and arrayability of the radiating elements.

No Convention Paper Printed

9:30 am

P-2 J and Spiral Line Arrays

Mark S. Ureda, JBL Professional, Northridge, CA, USA

Straight-line arrays produce highly directional polar response curves in the vertical plane, resulting in high on-axis gain. In many venues, however, it is useful to blend this high on-axis gain with improved response in the near field beneath and in front of the array. To accomplish this the lower section of a straight-line arry is curved. This paper derives the directivity functions of two such arrays, namely, the J array and spiral array.

Convention Paper 5485

10:00 am

P-3 Mixing Techniques for Multi-Channel (Left/Center/Right) Sound Reinforcement Systems

Vance Breshears, Sound Technology Consultants, Alpine, CA, USA

An increasing number of sound system designers are implementing multi-channel (primarily Left/Center/Right) sound reinforcement systems for both permanent installation, touring and show applications. Due to the large size of most performance venues and the speaker locations required to provide a stereo listening environment, the arrival times of the direct sound from primary speaker sources can be widely varying. Mixing techniques will be discussed and demonstrated through the use of auralizations. Basic mixing guidelines will be outlined.

Convention Paper 5486

10:30 am

P-4 Design Requirements for Sound Reinforcement Systems in Serbian Orthodox Churches

Miomir Mijic, Faculty of Electrical Engineering, Belgrade, Yugoslavia

Traditionally, Serbian Orthodox churches were small enough not to require sound reinforcement systems. However, during the last decade larger churches that required use of electroacoustical equipment were erected. They gave rise to the issue of aesthetical and functional requirements church audio systems needed to satisfy. The service in Serbian churches consists of acapela chorus' polyphonic singing coupled with preachers' chant. Results of recent acoustical research based on the analysis of autocorrelation function of signals recorded during the service, as well as subjective evaluation of acoustical quality, led to preliminary conclusions regarding desirable acoustical response in churches. This paper analyzes requirements for sound reinforcement systems in Serbian orthodox churches.

Convention Paper 5487

11:00 am

P-5 Wavefront Sculpture Technology

Marcel Urban, Christian Heil and Paul D. Bauman, L-Acoustics, Gometz La Ville, France

We introduce Fresnel's ideas in optics to the field of acoustics. Fresnel analysis provides an effective, intuitive approach to the understanding of complex interference phenomena and thus opens the road to establishing the criteria for the effective coupling of sound sources and for the coverage of a given audience geometry in sound reinforcement applications. The derived criteria form the basis of what is termed Wavefront Sculpture Technology.

Convention Paper 5488