V3.7 Acoustic Enhancements

The original single-stud assembly (12.5mm gypsum · 70mm studs · RWA45 · 12.5mm gypsum) achieved STC 48 — exactly the theoretical minimum needed to reduce a 80 dBA studio production level to the Editing Suite's NC-25 ambient target (~40 dBA). That left zero margin. Any flanking path, low-frequency bleed, or stud resonance would push audible noise above the NC-25 threshold during simultaneous use.

The upgrade adds a second 12.5mm gypsum layer on the Studio side with Green Glue compound between the two sheets. Green Glue converts sound energy into heat through constrained-layer damping, adding approximately 8 dB across mid and high frequencies where single-stud walls are weakest. The partition now delivers 5 dB of headroom above the NC-25 requirement, making simultaneous Studio recording and Editing Suite use genuinely viable.

A partition's acoustic performance is governed by its weakest element. Even after upgrading Wall 7 to STC 48, a STC 48 door in the same wall would have remained the limiting factor — the entire partition would effectively perform at STC 48 in the door zone. The Studio→Editing isolation gain from the wall upgrade would have been partially negated.

Upgrading D4 to STC 48 matches the door to the upgraded wall, creating a balanced partition with no weak link. At the door position, Studio 80 dBA now transmits at approximately 32 dBA into the Editing Suite — 8 dB below NC-25, compared to exactly NC-25 with the previous STC 48 door. A single door replacement before installation is significantly cheaper than retrofitting after handover.

The previous Control Room treatment spec — bass traps in all four corners, QRD diffusers on the rear wall, Rockfon ceiling cloud — achieved the RT60 target of 0.30s without any flat absorption panels on the side walls. The RT60 number was correct. However, RT60 does not capture early reflections.

In a nearfield monitoring environment, the primary acoustic concern after RT60 is the first reflection points — the spots on the left and right walls where direct sound from the monitors bounces once before reaching the mix position. Untreated, these reflections arrive 5–15 ms after the direct sound, causing comb filtering that colours the frequency response and compromises stereo imaging. This is audible on every mix as a smeared centre image and unreliable low-mid decisions.

Two panels — one per side at the first reflection point (~120 cm AFF, positioned by mirror method from the mix position) — eliminate this artefact without over-damping the room. The resulting RT60 of approximately 0.23s sits in the preferred range for broadcast monitoring (slightly dry, tight transient response). Four panels were considered but rejected: that would reduce RT60 to ~0.20s, making the room indistinguishable from the VO booth and losing the natural reverb tail needed for music mixing judgment.