Here is the projection in Hrec of acoustic noise of CEB, DLAB, NEB, WEB, MCB derived from white noise injections done on Aug 28 (CEB, DLAB - 39322) on Aug 30 (NEB, WEB - 39334) and Sept 20 (MCB - 39521). Attached figures show the projected noise (in blue is the upper limit  meaning where we injected acoustic noise at least  a factor 2 above quiet condition, in red is where also Hrec sensed an excess noise of at least a factor 2 above quiet). Also attached are .txt files which contain for each frequency: f, fft_Hrec_quiet, fft_Hrec_injection, fft_MIC_quiet, fft_MIC_injection, from which the "transfer function" can be recomputed as tf = fft_Hrec_injection./fft_MIC_injection.

For Mode Cleaner and terminal halls we do not find evidence of coupling to Hrec in the probed frequency region that is from 50Hz to 2kHz, we just measured an upper limit, as shown in the projections:

• Figure 1, injection location NEB hall: just upper limit, roughly a factor 20 below O2 sensitivity, measured from about 40Hz to 2kHz.
• Figure 2, injection location WEB hall: just upper limit, roughly a factor 20 below O2 sensitivity, measured from about 40Hz to 2kHz.
• Figure 3, injection location MCB hall: just upper limit, roughly a factor 5 below O2 sensitivity, measured from about 70Hz to 2kHz.

For CEB it is evidenced a weak coupling of acoustic/vibration noise in the region between 200Hz and 500Hz, and the noise is actually limiting at some peaks around 250-270Hz and 400-450Hz. This confirms the result found with the acoustic sweep. At these peaks the acoustic noise in the CEB hall seems more coupled than the acoustic noise in DET lab. This is shown in the projections:

• Figure 4, injection location CEB hall NORTH terrace (above DET lab)
• Figure 5, injection location CEB hall S-E corner on towers' floor (just below CEB_MIC)
• Figure 6, injection location inside DET Lab.