Sound Analysis of an Amphitheatre

Importing Model to Ecotect Anaysis.

.3ds geometry--Ecotect

.3ds geometry--Ecotect

Conclusion: Analysis will retard or take long time.

Revit and Ecotect

Tag the object carefully in Revit for gbxml filetype!

Revit model tagged as shaded part and untagged as un-shaded part.To import gbxml format from revit for analysis, whole part should be completely tagged

Conclusion: Analysis will work but cylindrical geometry will be a mess as ecotect converts it into triangular components.

Cylinder computed by Ecotect becomes more complex triangular geometry

Avoid Complex Geometry as far as possible.

Carefully deleted the outer cylindrical from imported xml file and created cylinder surface on ecotect so that analysis is done smoothly.

More Simplified geometry for Ecotect Model

Acoustical Analysis

Set Sound Source and Reflectors (ceilings)

Generate Rays

Reflector position and orientation calculationAcoustical Analysis

Trial 1Default

Trial 1

12m

dia=30m

Trial 1Default

12m

dia=30m

Trial 1Default

12m

dia=30m

Trial 1Default

dia=30m

12m

Conclusion of Trial 1

• More REVEB sound was detected.• Hence need to modify

-Geometry -Orientation (incident angle etc.)

• Material quality is kept as default.• Hence parameters to control in the analysis

are Reflectors (ceilings) property.

Trial 2Lowering ceiling

Decreased by 3m

9m

dia=30m

Trial 2Lowering ceiling

Decreased by 3m

9m

dia=30m

Decreased by 3mTrial 2

Lowering ceiling

9m

dia=30m

Trial 3Increased by 3m

15m

dia=30m

Trial 3

15m

dia=30m

Conclusion of Trials 2 and 3

• As we change the heights of the ceiling, just above the stage, quality changes drastically

• As we lower more noise is observed• As we higher the ceiling good quality is

observed for same directed ray generated.

Material assignment to the Reflectors at height of 12m

Acoustical Analysis

Assigning all reflectors as Acoustical Tile.

Table to feed different NRC Values

Feeding different Absorptive value for different frequency.

Adding Material-NRC.03

dia=30m

12m

Adding Material-NRC.03

12m

dia=30m

Adding Material-NRC.61

dia=30m

12m

Adding Material-NRC.85

dia=30m

12m

Conclusion of different NRC Values

• For Higher Noise Reduction Coefficients (NRC 0.6 and above) most of the sound waves are observed that leads to Dryness of Sound which seems to be bad of an amphitheatre.

• For lower NRC(0.3) we have variety of sound variation which is not desired

• Hence selected NRC 0.56 which is 12 mm Mineral Fiber Material which is also fire resistant.

Adding Material-NRC.56

12m

dia=30m

Adding Material-NRC.56

12m

dia=30m

Results or Output from Ecotect Analysis.Acoustical Analysis

Acoustical Response

Sound Decay for different frequency

Reverberation Graph

TOTAL SABINE NOR-ER MIL-SEFREQ. ABSPT. RT(60) RT(60) RT(60)------- -------- ------- ------- ------- 63Hz: 104.349 3.35 2.80 4.87125Hz: 110.039 3.21 2.70 1.70250Hz: 206.346 1.53 1.39 1.13500Hz: 519.030 0.86 0.68 0.57 1kHz: 579.543 0.80 0.60 0.49 2kHz: 485.506 0.86 0.71 0.62 4kHz: 390.240 1.04 0.90 0.82 8kHz: 390.551 1.02 0.90 0.8216kHz: 308.554 1.14 1.07 0.99

STATISTICAL ACOUSTICS - 18 Room

Volume: 4070.390 m3Surface Area: 761.794 m2Occupancy: 680 (850 x 80%)Optimum RT (500Hz - Speech): 0.99 sOptimum RT (500Hz - Music): 1.65 s

Volume per Seat: 4.789 m3Minimum (Speech): 5.329 m3Minimum (Music): 9.129 m3

Most Suitable: Norris-Eyring (Highly absorbant)Selected: Sabine (Uniformly distributed)