Why “STC 35” doesn’t mean what you think it does

If you’ve been shopping for soundproof booths, you’ve probably seen labels like “STC 35” or “35dB reduction.”

Here’s a secret: a booth that claims “STC 35” might actually only block about 20 to 22 dB of real sound in your office.

Why? Because they are using the wrong ruler.

STC measures a wall, not a room

STC (Sound Transmission Class) is a lab test originally made for permanent building walls. It tests a single flat panel in perfect lab conditions. But a booth has doors, vents, and seams. Every little gap lets sound leak out.

The real standard for booths is ISO 23351-1. This tests the entire assembled booth in real-world conditions. It literally just asks: “If I talk normally in here, how much can you hear outside?”.

What is Class A?

We explain this in detail on our FAQ page, but basically:

Class B (28–29 dB): Good for normal work.
Class A (30 dB+): Totally private. You can’t understand the words from the outside. Perfect for HR chats or sensitive calls.

The PC Phone Booth difference

If you want absolute privacy, look at the PC Phone Booth. It’s built with an aluminum honeycomb core to hit 45 dB+ of real sound reduction. It’s not just thick panels; it’s smart acoustic engineering.

You can compare it with our other models on the Office Pods overview page.

Don’t just trust a random “STC” number. Ask if it’s tested as a complete unit (ISO 23351-1). The PC Series gives you the proof, not just a pretty number.

Check out all our specs