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Predicted vs measured STI variation in small room
PostPosted: Mon Feb 20, 2023 3:01 pm Reply with quote
coliseum8299
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Joined: 12 Feb 2023
Posts: 4




Trying to get used to STI predictions in EASE Jr 4.4

I've created a model of my living room in EASE Jr 4.4. Placed a listened seat where the sofa is, and an NTi Talkbox in the model. The model of the living room is a simple box - I haven't included furniture, windows etc because this should be irrelevant (I think).

In my real living room, I've placed a Class 2 mic and NTi XL2 at my listener seat position, and measured the NTi Talkbox with the Pink Noise file included, set to be 70dBA at 1m (this really measures around 73-74dBA at 1m, which concurs with the Talkbox data in GLL Viewer). This measures 66.6dBA at 3.12m where my listener seat is, which taking into account loss over distance and the effect of the total SPL from the room, makes sense.

Separately, I've measured the RT60 of the room with the XL2 and inserted the figures into the EASE model (very short RT, 0.6s in the 125Hz octave band, 0.42s at 500Hz, 0.4s at 2k) alongside the background noise (very low levels around 18dBA).

I've then measured STIPA in the real room (using edn 5 STIPA signal in the Talkbox and measuring with the XL2 at my listener seat position). I get a figure of 0.81 and 67.4dB - again, to be expected.

The calculation at my listener seat in EASE, yields a direct SPL of 62.1dBA, and a total SPL of 66.9dBA (both broadband), which is very close to my real world measured results of the pink noise signal. However, the EASE model only yields an STI of 0.69, much lower than the real STI. I've selected Eyring and Male STIPA in the options, and although my version of EASE is still using edn4 of STIPA and I need to update, there shouldn't be such a huge difference (I also used edn4 STIPA in the Talkbox in the real living room and got pretty much identical measurements).

All my surfaces in the EASE model are set to be absorbers - does this matter, as I've told it the real measured RT values from the real room? I've used Pink Noise as an excitation signal in the Room Edit option. I must have done something wrong along the way - if anyone would be able to help please.
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PostPosted: Wed Feb 22, 2023 10:24 am Reply with quote
AFMG Silke Bögelein
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Joined: 14 Jul 2020
Posts: 44




First of all, I would like to point out that simulations in small rooms in EASE are only reliable above the Schroeder frequency, because below this frequency there are low-frequency effects, such as room modes, which are currently not covered by a simulation in EASE.

There are several options why a difference might occur.
Would it be possible to send us your packed project (select "Pack Project" from the EASE Main windows File menu) to support@afmg.eu ?
We will then take a closer look at your selections.

Regards,
Silke
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PostPosted: Fri Feb 24, 2023 9:30 pm Reply with quote
coliseum8299
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Joined: 12 Feb 2023
Posts: 4




Hello Silke, thank you very much for your kind offer to look at my project file. I will send it over.
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