Cistern Simulation at EMPAC

Prepared By braasj for xsead

Cistern Simulation at EMPAC

This project was first carried out at EMPAC and later presented at the Bang on a Can Marathon in 2012. Pauline Oliveros, Stuart Dempster and Brian Perti were the main performers in this project. Jonas Braasch, Anne Guthrie, and Sam Clapp and Todd Vos were involved with the Simulation Technology.


Concert with simulated cistern acoustics

The first concert with the live system was conducted at Rensselaer's Experimental Media and Performing Arts Center (EMPAC) in May 2013. Pauline Oliveros, Stuart Dempster, and Brian Perti were the main performers in this concert.


CAD simulation

The initial attempt to create an impulse response was made using a CAD model and auralization software. It turned out that the detailed imprint of the early reflections produced by the CAD model were not the best solution, when the Cistern was reproduced via loudspeakers. The addtional early reflections produced by the physical venue (e.g., EMPAC) are fully sufficient in conjuction with a smooth, extended reverberation tail. The latter was produced using octav-filtered, exponentially decaying Gaussian noise signals. The reverberation times in each frequency bands were adjusted to the specifications of the measured cistern impulse response.





Simulation Software in Max/MSP

The simulation software was written in Max/MSP using a Liquid Sonic Convolution Reverberator. Four channels of audio were sufficient to create a diffuse sound field, if these channels were distributed over 32 loudspeakers.


Acoustical Parameters

The green and red curves show the T20 reverberation times for the measured Cistern. For these measurements, the values below 200 Hz might be biased by the high noise floor at low frequencies. The blue curve shows the reverberation times for the Cistern CAD simulation, the magenta line for the reverberation times measured at EMPAC. The black curve, shows the reverberation time of EMPAC without the cistern simulation, the lowest value is too high, due to the noise floor.

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Prepared By braasj on behalf of XSEAD

Acknowledgements & Credits

Pauline Oliveros (V-Accordion, voice, cong shell), Stuart Dempster (Trombone, voice cong shell), Brian Perti (Tibetan Horn, voice, cong shell), Jonas Braasch, Sam Clapp, Anne Guthrie, Todd Vos (cistern simulation technology), Argeo Ascani (curator), Johannes Goebel (EMPAC director).

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