1. An Experimental Evaluation of Regular Polyhedron Loudspeakers as Omnidirectional Sources of Sound Sarah Rollins Timothy W. Leishman Acoustics Research Group Department of Physics and Astronomy Brigham Young University November 11, 2003

2. Introduction Architectural AcousticsArchitectural Acoustics Omnidirectional source Omnidirectional source Dodecahedron loudspeaker Dodecahedron loudspeaker Regular PolyhedronsRegular Polyhedrons Regular Polyhedron Loudspeakers (RPLs)Regular Polyhedron Loudspeakers (RPLs) What about other RPLs besides the dodecahedron? What about other RPLs besides the dodecahedron?

3. Regular Polyhedron Loudspeakers Built all 5 RPLsBuilt all 5 RPLs 2 categories2 categories Equal Volume per Driver (EV) Equal Volume per Driver (EV) Equal Midradii (EM) Equal Midradii (EM)

4. Experimental Setup

5. Current Standard

8. Standard Deviation Formulation Standard deviation of directivity balloon valuesStandard deviation of directivity balloon values Advantages over current methodsAdvantages over current methods Visualization Visualization Full sphere Full sphere DisadvantagesDisadvantages More time consuming More time consuming More equipment More equipment

9. Standard Deviation Plots

10. Figure of Merit Table PPL 4 kHz, σ(dB) 8 kHz, σ(dB) Tetrahedron*1.562.29 EM Hexahedron 1.802.28 EV Hexahedron 1.962.35 EM Octahedron 2.032.44 EV Octahedron 2.26 2.262.60 EM Dodecahedron 1.61*2.19 EV Dodecahedron 1.992.32 Icosahedron2.122.46 Average1.922.37 * Indicates the lowest value for the given frequency range

11. Conclusions Best omnidirectional sourceBest omnidirectional source Depends on bandwidth Depends on bandwidth TetrahedronTetrahedron 0-4 kHz octave band 0-4 kHz octave band Contradicts ISO 3382 Contradicts ISO 3382 DodecahedronDodecahedron 0-8 kHz octave band 0-8 kHz octave band More power output More power output

12. Further Research Higher resolution measurementsHigher resolution measurements High frequency information High frequency information Impulse response measurementsImpulse response measurements Compare measurements for different RPLs and different orientations Compare measurements for different RPLs and different orientations Further comparison of standard deviation with current methods to quantify omnidirectivityFurther comparison of standard deviation with current methods to quantify omnidirectivity Analytical and numerical calculationsAnalytical and numerical calculations Different size RPLs Different size RPLs

13. Acknowledgments Funding: NSF REU programFunding: NSF REU program Advisor: Dr. Timothy W. LeishmanAdvisor: Dr. Timothy W. Leishman Gordon DixGordon Dix Kent GeeKent Gee Todd KitchenTodd Kitchen Wesley LifferthWesley Lifferth Jacob RobinsonJacob Robinson