Letters

The use of multichannel playback for sound diffusion has a long and bifurcated history in electro-acoustic music. A decidedly European approach (acousmatic diffusion) imagined collections of speakers distributed across stages and audiences to diffuse sounds within contained spaces. Speakers became “instruments” in an orchestra of loudspeakers. Spatial positioning was secondary to color, timbre, and size. A decidedly American approach conceived of equally spaced loudspeakers that are the boundary for a virtual acoustic world beyond its edges.

The challenge for both of these approaches is reproducibility: How can composers be sure their works will sound the same whether performed in Baton Rouge, Bowling Green, or Birmingham? This challenge is only exacerbated by the move towards building very large, massively multiple speaker arrays for acousmatic works, surround sound, and wave-field synthesis. For a creative field that cherishes the finest details of sound, this appears to be an unsolvable problem.

Forget about reproducibility. Unless you recreate an HDLA or standardize an HDLA configuration, it is indeed an impossible dream. It is better to embrace HDLAs as we do the grand organs of Europe. Each one has similar capabilities and registrations, but no one is in fact the same. I’m sure that Bach or Saint-Saens organ sonatas sound different on different organs in different cathedrals. Yet those performances are still of the same piece, and we accept that without reservation.

We should move away from reproducibility towards producibility. Focus on how we perform works in different arrays and spaces. Focus less on the exactitude of our musical renderings and more on the articulation of musical ideas. Focus on the technologies that will allow us to diffuse sounds through idiosyncratic environments with virtuosity and control. Embrace the ephemera of the moments that define our musical experiences.

Stephen David Beck
Baton Rouge, Louisiana, USA

The advantage of being able to break up the perspectival field into a higher spatial resolution of sound sources (loudspeakers) makes HDLAs very useful for complex textural topographies, where sound exists simultaneously in multiple localities of the listening environment. Some of the potentials that I see with HDLAs include: greater ability to establish complex spatial zones of activity; designing dynamic multidimensional textures; working with multiple spatial foci; and increasing textural density without losing clarity. To a work that has no rigorous spatial aesthetic reasoning behind it, however, an HDLA is likely to make a trivial difference at best.

Technically, I view composition and performance for HDLAs as a challenge related to synthesis of spatial texture. I currently work with real-time textural processes whose localized constituents are individual across a variable quantity of channels across areas of the speaker system, meaning that the mass of sound in the texture expands with the number of channels. Channels also have a role in the algorithms that structure the texture, so complexity of spatial behaviors and patterns can also be affected by the size and configuration of the system. The spatial integrity of a texture is determined through balancing global coordination (correlated properties) and localized differentiation (uncorrelated properties) across spatially distributed streams of sound. This involves identifying how temporal and spectral morphological aspects are relatively structured among channels. Motion is usually achieved indirectly through relative spectral and temporal properties creating biases of density, and emergent trajectories, patterns, or entropic behaviors. Spatiality thus becomes a by-product of multidimensional sound design.

I currently try to take advantage of the differences between speaker systems by making each performance as site-specific as possible, keeping works real time rather than fixed media, so the material remains adaptable, in that synthesis processes can be optimized for different configurations and controlled live. Thus my approach is not so much about spatially orienting already composed sounds, as in, for example, conventional manual diffusion or Ambisonic distribution, but more about allowing the texture synthesis design to integrate as much as possible with the potentials of the specific system at hand.

Erik Nyström
Birmingham, UK

The notion of technical systems designed to accommodate mass sound structure is highly appealing to many artists, whether one is preoccupied with large-scale sonification installations or the diffusion...