Spatial audio has been at the core of the multimodal experience at the AlloSphere, a unique instrument for data discovery and exploration through interactive immersive display, since its conception. The AlloSphere multichannel spatial audio design has direct roots in the history of electroacoustic spatial audio and is the result of previous activities in spatial audio at the University of California at Santa Barbara. A concise technical description of the AlloSphere, its architectural and acoustic features, its unique 3-D visual projection system, and the current 54.1 Meyer Sound audio infrastructure is presented, with details of the audio software architecture and the immersive sound capabilities it supports. As part of the process of realizing scientific and artistic projects for the AlloSphere, spatial audio research has been conducted, including the use of decorrelation of audio signals to supplement spatialization and tackling the thorny problem of interactive up-mixing through the Sound Element Spatializer and the Zirkonium Chords project. The latter uses the metaphor of geometric spatial chords as a high-level means of spatial up-mixing in performance. Other developments relating to spatial audio are presented, such as Ryan McGee's Spatial Modulation Synthesis, which simultaneously explores the synthesis of space and timbre.

This article describes a quest for the GRAIL (Giant Radial Array for Immersive Listening), a large-scale loudspeaker system with related hardware and software control equipment. The GRAIL was developed at the Center for Computer Research in Music and Acoustics (CCRMA) at Stanford University, evolving from the need for optimal sound quality in our multichannel concerts. It is also used for teaching and research. The current GRAIL is one step in an ongoing evolutionary process, characterized by the use of off-the-shelf hardware components and custom software–based on free software languages and libraries. While developing our software, we have, as much as possible, aimed to take advantage of existing programs and utilities.

This article offers an alternative for spatializing electroacoustic music using high-density loudspeaker arrays (HDLAs). It describes and contextualizes experimentation with the large array of speakers of the Cube concert hall made during the Spatial Audio Workshop residency at the Moss Arts Center, Virginia Polytechnic Institute and State University in August 2015. The experiments were performed using the implementation of “Granular Spatialisation” (GS), a technique developed by the author for sound diffusion in HDLAs. This is based on the projection of sound using spatial grains of “microdurations,” with ideally one grain individually addressing each speaker of the array. The article focuses on particular aspects of, challenges from, and strategies for using GS for the projection of sound with the Cube's array of 138 loudspeakers, including four independent subwoofers, while composing a new acousmatic piece that was diffused in the Cube at the end of the residency.

This article presents a report on technological and aesthetic practices in the variable-acoustics performance hall, Espace de Projection, at the Institut de Recherche et Coordination Acoustique/Musique. The hall is surrounded by a 350-loudspeaker array for sound-field reproduction using holophonic approaches such as wave-field synthesis and higher-order Ambisonics. First we present the design and implementation of the audio system and discuss the challenges of both hardware and software architectures. This is followed by a discussion of spatial composition techniques, aesthetic approaches, and methodologies for composing computer music for high-density loudspeaker arrays, explored through the paradigmatic examples of pieces produced by two artist-in-research residencies.

Historically, most acousmatic works were composed in stereo and performed, or “diffused”, over loudspeaker orchestras. These systems furnished performers and composers with a wealth of opportunities to enhance the spatial contrast, motion, and musical articulations latent in the music. Although loudspeaker orchestras, stereo diffusion, and—more recently—hybrid performance techniques remain alive, especially in Europe, there is a trend towards fixed installation, high-density loudspeaker arrays (HDLAs), which I will call permanent HDLAs to differentiate them from loudspeaker-orchestra HDLAs. Permanent HDLAs (P-HDLAs) stimulate alternative approaches to musical space and pose challenges in both spatial composition and performance, encompassing both technology and aesthetics. This article consolidates many of the technical and aesthetic approaches that I have found specific to P-HDLAs with an emphasis on the application of higher-order Ambisonics (HOA) at fourth-order 3-D and above—what I will call V-HOA (“very high-order” Ambisonics) as distinguished from lower orders, or L-HOA (lower than fourth-order HOA). These approaches are guided by spatial-audio research, and then developed in a musical context. The study is divided into three sections: a description of musical and technical approaches that I have found to function over different P-HDLA installations; reflections on the compromises of lower-order monitoring during the compositional process; and presentation of the “Virtualmonium”: an instrument for the performance of stereo works that benefits from the growing popularity of P-HDLA installations.

The Cube is a recently built facility that features a high-density loudspeaker array. The Cube is designed to support spatial computer music research and performance, art installations, immersive environments, scientific research, and all manner of experimental formats and projects. We recount here the design process, implementation, and initial projects undertaken in the Cube during the years 2013–2015.