AFMG Network Forum

Bartek Zdeb · Member

Hi everyone,
I design the acoustic adaptation of the existing multi-functional hall. First, in the model, I optimized the calculation parameters so that they did not affect the results in Aura v.4 (number of particles = high, length = long, scattering = auto S-curve 10% -40%, 2 sources, 5 receivers). I needed a shorter RT reverberation time at 250 Hz, so I used a material with an absorption coefficient higher by 0.50 for this frequency, area share ~ 23%. After the calculations, I was very surprised as the calculated RT was the same or higher at 250 Hz instead of lower (the RT in Optimize RT at 250 Hz is 0.12 sececond shorter). I tried several times, the results were similar. In the remaining frequencies, the RT behaved predictably. How can this be explained? Have you had such experiences?

Agustín Arias · Member

Hi bartek
It will be difficult to give you an adequate answer without exploring your model. But, first of all, did you check the statistical reverberation time (Sabine/Eyring)? Did you see the same effect at 250 Hz?

Bartek Zdeb · Member

Hi Agustin,
The answer is in my post. The difference of 0.12 seconds is 30% of the statistical reverberation time.

Agustín Arias · Member

Hi bartek,
In that case, it will be very difficult (at least for me) to give you an adequate answer without inspecting the model...

matthew.g.easlon · Member

I've had a similar issue with AURA where I add more absorption (several thousand square feet of NRC 0.95) and the T20 value across a wide band of frequencies increases by a factor of 10-20% or more rather than decreases. I haven't figured out a solution yet.