Hello,
I created a simple room (10*10*3 meter) in Ecotect to compare the reverbaration time (Ecotect) with the logarithm of SABINE RT60=0,163*V/A*alpha) at 500Hz.
Material from the libary: BrickPlaster

The calculated reverbaration time (Ecotect) is not the same as the reverbaration time calculated with the logarithm of SABINE at 500Hz.

my calculation:

Logarithm of SABINE:
RT60=0,163*300/(320*0,02)=7,64 sec

Ecotect:
STATISTICAL ACOUSTICS - Zone 1
Model:

Volume: 300.000 m3
Surface Area: 320.000 m2
Occupancy: 0 (0 x 50%)
Most Suitable: Sabine (Uniformly distributed)
Selected: Sabine (Uniformly distributed)

TOTAL SABINE NOR-ER MIL-SE
FREQ. ABSPT. RT(60) RT(60) RT(60)
------- ------- ------- ------- -------
63Hz: 32.000 1.49 1.41 1.41
125Hz: 22.400 2.02 1.96 1.96
250Hz: 9.600 3.27 3.23 3.23
500Hz: 6.400 3.41 3.39 3.39
1kHz: 6.400 1.49 1.49 1.49
2kHz: 6.400 0.70 0.70 0.70
4kHz: 9.600 0.50 0.50 0.50
8kHz: 6.400 0.15 0.15 0.15
16kHz: 9.600 0.21 0.21 0.21

Thanks!

Reiner