acoustics of a planetarium micah shepherd, timothy w. leishman, utami sentagi acoustics research...
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Acoustics of a Planetarium
Micah Shepherd, Timothy W. Leishman, Utami Sentagi
Acoustics Research GroupDepartment of Physics and Astronomy
Brigham Young University
150th Meeting of the Acoustical Society of America
20 October 2005
Summerhays Planetarium Located on the Brigham Young
University campus Recently renovated Serves as a planetarium and classroom Seating capacity: 119 Dome radius: 38’ Ziess zkp3 star projector Good classroom acoustics?
Overview
Motives: Astronomy faculty and Summerhays Planetarium supervisor desired good classroom acoustics
I. Acoustic recommendations given and implemented
II. Room acoustic measurements taken after construction completed
Acoustic Modeling CAD drawings made in
EASE®
Dome modeled using 303 Planar faces
Dome treatments: Hard surface 2.68” BASWAphon®
smooth, even finish Side wall treatments:
Gypsum board Alternating absorptive
panels RPG diffusors
Room parameters T30, C50, STI calculated and analyzed
Predicted Results
Outline of dome
front
Source 1
Source 2Seat aisles
Star projector
Omnidirectional Source
Other parameters STI results very similar to C50 results Average T30
1.8 sec no dome treatment 1.1 sec dome treatment
Listening tests using auralizations Room treatment found to be necessary
for good intelligibility Dome treatment and alternating
absorptive/ reflective wall panels were recommended, accepted and implemented
Room Measurements 23 receiver locations 2 source locations
Lecture podiums in front and back of room
Dodecahedron source Single driver active All drivers active
PA system 2 EAW dsa-250
(digitally steerable arrays)
Directional source with microphone
Other parameters
STI again very similar to C50 Average T30: .90 sec Fair to good agreement with
predicted parameters
Conclusions BASWAphon can partially control unwanted
reflections from a planetarium dome while providing an excellent projection surface
Directional loudspeaker arrays keep sound out of the dome and therefore improve speech intelligibility
With appropriate acoustical planning, planetariums can also function as classrooms
Planetarium users are very pleased with the acoustics of the Summerhays Planetarium