The number of panels depends on three things: the room's volume, how much its surfaces already absorb, and how short you want the echo to be. Here is the calculation for a typical podcast room, step by step.
Step 1: the room
A typical podcast room of 12 × 10 ft with a 9 ft ceiling has a volume of about 1,080 ft³. With typical surfaces (drywall, a rug and some furniture), its echo time is about 0.83 seconds. The target for podcast rooms is 0.30 seconds.
Step 2: how much absorption is missing
Sabine's formula says RT60 = 0.161 × V ÷ A, with V in cubic meters and A, the total absorption, in square-meter sabins. To reach 0.30 s, the room needs about 177 ft² sabins of absorption in total. It already has about 64 from its surfaces, so the panels must add the rest.
Step 3: what one panel adds
A 24 × 21 in hexagon panel, 2 in thick has about 2.6 ft² of face. At NRC 1.00, and allowing for the surface it covers, it adds about 2.3 sabins.
Step 4: the answer
About 49 panels bring the room from 0.83 s to 0.30 s.
| Thickness | NRC | Panels needed | Echo time after |
|---|---|---|---|
| 1 in | 0.8 | 63 | 0.30 s |
| 2 in | 1 | 49 | 0.30 s |
| 4 in | 1.15 | 42 | 0.30 s |
| Room | Size | Volume | Echo time now | Panels needed |
|---|---|---|---|---|
| Small | 9 × 8 × 9 ft | 648 ft³ | 0.71 s | 27 |
| Typical | 12 × 10 × 9 ft | 1,080 ft³ | 0.83 s | 49 |
| Large | 18 × 15 × 11 ft | 2,970 ft³ | 1.15 s | 154 |
These are estimates for speech frequencies (500–1,000 Hz). Use the room calculator with your own measurements, then load the result into the designer.