an experimental evaluation of regular polyhedron loudspeakers as omnidirectional sources of sound
DESCRIPTION
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. Introduction. Architectural Acoustics - PowerPoint PPT PresentationTRANSCRIPT
An Experimental An Experimental Evaluation Evaluation
of Regular Polyhedron of Regular Polyhedron LoudspeakersLoudspeakers
as Omnidirectional as Omnidirectional Sources of SoundSources of Sound
Sarah RollinsSarah RollinsTimothy W. LeishmanTimothy W. Leishman
Acoustics Research GroupAcoustics Research GroupDepartment of Physics and AstronomyDepartment of Physics and Astronomy
Brigham Young UniversityBrigham Young UniversityNovember 11, 2003November 11, 2003
IntroductionIntroduction• Architectural AcousticsArchitectural Acoustics
• Omnidirectional sourceOmnidirectional 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?
Regular Polyhedron Regular Polyhedron LoudspeakersLoudspeakers
• 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)
Experimental SetupExperimental Setup
Current StandardCurrent Standard
63 125 250 500 1000 2000 4000 8000-12
-8
-4
0
4
8
12
Frequency (Hz)
Dev
iatio
n (d
B)
ISO 3382-Equal Volume per Driver RPLs
ISO 3382 Tetrahedron Hexahedron Octahedron Dodecahedron Icosahedron
Standard Deviation Standard Deviation FormulationFormulation
• Standard deviation of Standard deviation of directivity balloon directivity balloon valuesvalues
• Advantages over Advantages over current methodscurrent methods• VisualizationVisualization• Full sphere Full sphere
• DisadvantagesDisadvantages• More time consumingMore time consuming• More equipmentMore equipment
n
ii xx
n 1
2)(1
1
n
mmxn
x1
1
)log(102
Hx
Standard Deviation PlotsStandard Deviation Plots
125 250 500 1000 2000 4000 80000
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Frequency (Hz)
Sta
ndar
d D
evia
tion
(dB
)
(10log(|H|2))
TetrahedronEM HexahedronEV HexahedronEM OctahedronEV OctahedronEM DodecahedronEV DodecahedronIcosahedron
Figure of Merit TableFigure of Merit Table
PPLPPL 4 kHz, σ(dB)4 kHz, σ(dB) 8 kHz, σ(dB)8 kHz, σ(dB)
TetrahedronTetrahedron *1.56*1.56 2.292.29
EM HexahedronEM Hexahedron 1.801.80 2.282.28
EV HexahedronEV Hexahedron 1.961.96 2.352.35
EM OctahedronEM Octahedron 2.032.03 2.442.44
EV OctahedronEV Octahedron 2.262.26 2.602.60
EM DodecahedronEM Dodecahedron 1.611.61 *2.19*2.19
EV DodecahedronEV Dodecahedron 1.991.99 2.322.32
IcosahedronIcosahedron 2.122.12 2.462.46
AverageAverage 1.921.92 2.372.37
* Indicates the lowest value for the given frequency range
ConclusionsConclusions
• Best omnidirectional Best omnidirectional source source • Depends on bandwidthDepends on bandwidth
• TetrahedronTetrahedron• 0-4 kHz octave band0-4 kHz octave band• Contradicts ISO 3382Contradicts ISO 3382
• Dodecahedron Dodecahedron • 0-8 kHz octave band0-8 kHz octave band• More power outputMore power output
Further ResearchFurther Research
• Higher resolution measurements Higher resolution measurements • High frequency informationHigh frequency information
• Impulse response measurementsImpulse response measurements• Compare measurements for different RPLs Compare measurements for different RPLs
and different orientationsand different orientations• Further comparison of standard Further comparison of standard
deviation with current methods to deviation with current methods to quantify omnidirectivityquantify omnidirectivity
• Analytical and numerical calculationsAnalytical and numerical calculations• Different size RPLsDifferent size RPLs
AcknowledgmentsAcknowledgments
• 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