Sound transmission class (STC), explained
STC is a single number describing how well a building element, usually a wall, blocks airborne sound in a laboratory. It is the most quoted figure in the office pod category and it is the wrong one, for reasons worth understanding before you compare two quotations.
What it measures
A sample of wall is built into an opening between two laboratory rooms. Sound is played on one side, measured on the other, and the difference is recorded across sixteen frequency bands. That curve is then compared against a standard reference contour, and the single STC number is read off where the curve fits. Higher is better. A domestic stud wall is around 33, a good office partition around 45, and a recording studio wall well above 60.
Why it is the wrong number for a pod
Three reasons, and they compound.
STC rates a panel, not a product. A pod is an assembly with a door, seals, a ventilation path and joints, and every one of those is a weaker point than the panel itself. A pod built from STC 40 panels does not perform at 40, because sound does not politely go through the wall when there is a door beside it.
STC ignores low frequencies. The rating starts at 125 Hz, which excludes most of the rumble that travels best through a building. It was designed that way for walls between apartments and it flatters small enclosures.
And STC is a laboratory installation with no ventilation running. A pod has to move air, and the duct that moves it is a hole in the acoustic envelope. A figure measured with that switched off is not the product you are buying.
So when a supplier quotes a panel STC for a pod, they are quoting a real number about the wrong thing.
What to ask for instead
Ask for speech level reduction measured on the assembled pod under ISO 23351-1, with ventilation running. That standard exists precisely because the building standards were being misapplied to furniture.
FocusPod is laboratory tested at greater than 29 dB speech level reduction under ISO 23351-1, measured assembled, ventilation on. Our accessible model tests at 30 dB, which is Class A under that standard.
Where FocusPod stands
Greater than 29 dB speech level reduction across the range, laboratory tested under ISO 23351-1, measured on the assembled pod with the ventilation running. The accessible model tests at 30 dB, Class A, with reverberation under 0.4 seconds. Test reports are available on request for any model you are specifying.
The rest of the terms
Every acoustic term you will meet in a pod quotation, explained the same way.