An Acoustical Study of An Acoustical Study of the the

Salt Lake TabernacleSalt Lake TabernacleSarah RollinsSarah Rollins

Timothy W. LeishmanTimothy W. Leishman

Acoustics Research GroupAcoustics Research GroupDepartment of Physics and Department of Physics and

AstronomyAstronomyBrigham Young UniversityBrigham Young University

147147thth Meeting of the Meeting of the Acoustical Society of AmericaAcoustical Society of America

May 25, 2004May 25, 2004

OverviewOverview

BackgroundBackground MeasurementsMeasurements ResultsResults ConclusionsConclusions Further WorkFurther Work

MotivationsMotivations

Characterize the acousticsCharacterize the acoustics Modern equipment and techniquesModern equipment and techniques Benchmark measurementsBenchmark measurements

Spatial variation of parametersSpatial variation of parameters Hall geometryHall geometry Spatial statisticsSpatial statistics

MeasurementsMeasurements SourcesSources

Dodecahedron loudspeakerDodecahedron loudspeaker Sound reinforcement systemSound reinforcement system

ReceiversReceivers Omnidirectional microphoneOmnidirectional microphone Multi-pattern microphoneMulti-pattern microphone KEMARKEMAR

MeasurementsMeasurements Maximum Length SequenceMaximum Length Sequence

Source PositionsSource Positions

Early Decay TimeEarly Decay Time

Color Range Beg. Range End Percent 2.00 2.25 0.0 2.25 2.50 0.0 2.50 2.75 0.1 2.75 3.00 0.2 3.00 3.25 2.8 3.25 3.50 12.3 3.50 3.75 12.4 3.75 4.00 16.8 4.00 4.25 23.9 4.25 4.50 14.5 4.50 4.75 5.5 4.75 5.00 3.8 5.00 5.25 3.1 5.25 5.50 3.3 5.50 5.75 1.3 5.75 6.00 0.0

Average: 4.10Average: 4.10 Std: Std: 0.680.68

Clarity Factor (CClarity Factor (C8080))

Color Range Beg. Range End Percent -11.00 -10.00 1.5 -10.00 -9.00 3.1 -9.00 -8.00 4.7 -8.00 -7.00 5.6 -7.00 -6.00 13.1 -6.00 -5.00 13.6 -5.00 -4.00 14.7 -4.00 -3.00 19.1 -3.00 -2.00 9.9 -2.00 -1.00 5.1 -1.00 0.00 4.0 0.00 1.00 2.8 1.00 2.00 1.8 2.00 3.00 0.8 3.00 4.00 0.2 4.00 5.00 0.0

Average: Average: -- 4.52 4.52 Std: 2.92Std: 2.92

Dietsch Echo Criterion for MusicDietsch Echo Criterion for Music

Color Range Beg. Range End Percent 0.00 0.13 0.0 0.13 0.25 0.0 0.25 0.38 0.0 0.38 0.50 0.0 0.50 0.63 0.6 0.63 0.75 12.5 0.75 0.88 20.7 0.88 1.00 16.7 1.00 1.13 17.3 1.13 1.25 12.9 1.25 1.38 12.4 1.38 1.50 3.0 1.50 1.63 1.9 1.63 1.75 1.5 1.75 1.88 0.4 1.88 2.00 0.0

Average: 1.00Average: 1.00 Std: Std: 0.290.29

Lateral FractionLateral Fraction

Color Range Beg. Range End Percent 0.00 0.03 0.1 0.03 0.06 3.7 0.06 0.09 10.3 0.09 0.12 13.3 0.12 0.15 16.1 0.15 0.18 14.1 0.18 0.21 9.2 0.21 0.24 9.0 0.24 0.27 9.3 0.27 0.30 7.7 0.30 0.33 4.8 0.33 0.36 2.0 0.36 0.39 0.4 0.39 0.42 0.0 0.42 0.45 0.0 0.45 0.48 0.0

Average: 0.17Average: 0.17 Std: Std: 0.090.09

Binaural Quality IndexBinaural Quality Index

Color Range Beg. Range End Percent 0.00 0.06 0.0 0.06 0.12 0.0 0.12 0.18 0.1 0.18 0.24 0.5 0.24 0.30 2.1 0.30 0.36 6.2 0.36 0.42 7.8 0.42 0.48 7.8 0.48 0.54 8.6 0.54 0.60 12.2 0.60 0.66 13.1 0.66 0.72 18.9 0.72 0.78 15.1 0.78 0.84 6.2 0.84 0.90 1.5 0.90 1.00 0.0

Average: 0.59Average: 0.59 Std: Std: 0.180.18

StatisticsStatistics

ParameterParameter AverageAverage Standard DeviationStandard Deviation

EDTEDT 4.104.10 0.680.68

C80C80 -4.52-4.52 2.922.92

Dietsch MusicDietsch Music 1.001.00 0.290.29

LFLF 0.170.17 0.090.09

BQIBQI 0.590.59 0.180.18

ConclusionsConclusions

Hall geometry affects parametersHall geometry affects parameters Values show focusing effectsValues show focusing effects

EDT, CEDT, C80 80 more uniform over main floor more uniform over main floor

than in the balconythan in the balcony Higher LF in the very center of the roomHigher LF in the very center of the room

Further WorkFurther Work

ProcessingProcessing More detailed statisticsMore detailed statistics Computer Modeling (CATT, EASE)Computer Modeling (CATT, EASE)

Current acousticsCurrent acoustics Historical acousticsHistorical acoustics

No BalconyNo Balcony No Choir LoftNo Choir Loft Smaller Organ CaseSmaller Organ Case Pine TreesPine Trees

AcknowledgementsAcknowledgements

Timothy W. LeishmanTimothy W. Leishman BYU Acoustics Research GroupBYU Acoustics Research Group