acoustics of a planetarium micah shepherd, timothy w. leishman, utami sentagi acoustics research...

20
a Planetarium Micah Shepherd, Timothy W. Leishman, Utami Sentagi Acoustics Research Group Department of Physics and Astronomy Brigham Young University 150 th Meeting of the Acoustical Society of America

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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

C50 no dome treatment, diffusers

Source 1Source 1

C50 dome treatment, diffusers

Source 1

C50no dome treatment, diffusers

Source 2

C50dome treatment, diffusers

Source 2

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

Measured C50 (Omni source)

Source 1

Measured C50 (Dir source)

Source 1

Measured C50(PA system)

Source 1

Measured C50 (Omni source)

Source 2

Measured C50 (Dir source)

Source 2

Measured C50(PA system)

Source 2

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

Thank you