Noise projections are attached: Figure 1 and Figure 2 (zoom in the 400-450Hz region). Respect to before the baffling when both the 250-270Hz region and the 400-450Hz region were limited by acoustic noise, now only the 400-450Hz region remains affected. This is consistent with the disappearence of 250-270Hz peaks.

While before baffling acoustic  noise coupled mainly at the 409 and 441Hz peaks,  now it couples mainly at the 420 and 452Hz peaks. This supports the hypothesis that it is the same peaks that moved consequently to SDB1 interventions.

After yesterday tappings we know these peaks excite when seismically exciting SDB1 vacuum walls.