Two flight simulator doors, measured before and after. The difference is 6 to 8 decibels and it’s audible the moment you walk past.

Client Civil Aviation Authority of Singapore	Location Singapore Aviation Academy
Service Acoustic Testing & Treatment	Completed 2025
Scope Simulation Room Door Acoustic Seals

+8 dB

Measured improvement at the corridor-to-simulation-room door, STC 11 to STC 19

+6 dB

Measured improvement at the simulation room to pilot console room door, STC 11 to STC 17

1 Week

From pre-construction baseline test to seal installation to post-construction verification

The Situation

The Civil Aviation Authority of Singapore engaged Soundzipper to improve sound isolation at the Singapore Aviation Academy’s flight simulation facility. Two doors were the focus: the door between the corridor and the simulation room, and the door between the simulation room and the pilot console room. In a flight training environment, what happens inside the simulator needs to stay contained, and what happens in the corridor outside cannot be allowed to interfere with a training session in progress. The brief was narrow and specific: measure how the doors were currently performing, install acoustic seals to close the gap, and verify the improvement with the same tests repeated afterward.

What We Found

Pre-construction testing established a baseline using Apparent Sound Transmission Class (ASTC) measurements, taken in accordance with ASTM E336. Both doors measured STC 11, a low rating that meant normal corridor noise was readily audible inside the simulation room and vice versa. A SoundCam acoustic camera was used alongside the standard sound level measurements to visually pinpoint exactly where sound was leaking around the door frame. The resulting sound map showed leakage spread broadly across the entire door perimeter, with overall sound intensity levels measured between 64.2 and 68.2 dB concentrated along the door edges. The cause was clear: the doors themselves were adequate, but without proper perimeter sealing, sound was finding its way around them rather than through them.

What We Designed

Soundzipper specified and installed a full acoustic seal system at both doors: bronze anodised perimeter seals, Batwing seals along the door edges, and drop seals at the threshold. No structural changes were made to the doors themselves. Post-construction testing, conducted with the air conditioning running normally to reflect real operating conditions, measured the same two doors again. The corridor-to-simulation-room door improved from STC 11 to STC 19, an 8 dB gain. The simulation-room-to-console-room door improved from STC 11 to STC 17, a 6 dB gain. A 6 to 8 dB improvement is large enough to be clearly audible, not just measurable on paper. The follow-up SoundCam scan confirmed why: sound leakage that had previously spread across the full door perimeter was now concentrated only at the centre meeting point of the double doors, with intensity levels reduced to between 61.3 and 65.6 dB. The perimeter seal had done exactly what it was specified to do. For CAAS, the result is two simulation room doors that now properly contain what happens on each side of them, achieved without touching the doors themselves.