STI measurements

In the meanwhile, I did the STI processing using "my" set of 4 WAV files, which I linked in my previous message.
First I imported them in Audacity:

As you see, I selected all 4 of them (CONTROL-A).
Then I invoked Tools - Aurora STI and selected the Fullscale Calibration label.
Here I choose which of the 4 files contains the calibration recording, I specify the calibration level in dB (68 dB in this case, but usually it is 94) then I press the button "Calibrate" and here is what I get:

Now I go to the next label, titled SNR Calculation. Here again I specify the file names for the background noise and for the Signal+Noise WAV files:

And I click on the "Compute Levels" button. A popup window appears, showing the computed spectra of Background Noise, Signal and Signal+Noise:

As you see the levels are NOT zero... And after closing this popup window, the new SPL value for Background Noise, Signal and Signal+Noise levels are shown in the table.
Finally I go on the Room Impulse Response label, and again I select the file name containing the IR:

Now the plugin has all the data required for computing STI. So I click on the "Compute STI" button, and the final window showing the STI calculation results is shown:


If you give me access to your 4 WAV files, I can repeat the same processing with them, and see what is wrong...

I got access to the 4files and checked if they works.
I could not complete the STI calculation, as you did not post the IR, just a sine sweep, which cannot be processed without its own matched Inverse Filter signal..
I assumed the calibration was done with a 94 dB standard calibrator (the calibration WAV file name usually always contains the explicit indication of the calibration level in dB !!!)
After calibrating at 94 dB (the Full Scale value resulted 111 dB) I did the SPL analysis of your WAV files.
The levels, indeed, are low, very low, so something seems to be wrong in your measurement setup. Perhaps you did change sone gain between the calibration and the recording...
Of course you should not change anything after recording the calibration signal!
But the results are NOT negative dB. so you Windows system is badly misconfigured.
I looked in the images you sent me, and possibly I did find the problem: you appears to be using an horrible and unstable FRENCH version of Audacity, and possibly also using a terrible FRENCH version of Windows, with FRENCH international parameters (comma instead of decimal point, etc.)....
EVRUTHING UST BE IN ENGLISH for scientific programs to work reliably !!!
As a starting point, set the International Parameters of Windows to English-UK mode, so that the decimal dot is used, and try again.
But I warmly recommend that everyone always employs always and only native English version of the operating system and of any program employed.