Thicker panels absorb lower frequencies. The right thickness depends on what you are trying to control in gyms: mostly crowds, balls and the PA.
| Thickness | NRC | 125 Hz | Best for |
|---|---|---|---|
| 1 in | 0.80 | 0.08 | Speech and high-pitched noise |
| 2 in | 1.00 | 0.24 | Most rooms, all-round |
| 4 in | 1.15 | 0.70 | Bass, music, theaters |
Our pick for gyms: 2 in. It handles the full range of speech and some of the low-mid build-up without taking up much space.
An air gap behind a panel acts like extra thickness at low frequencies. A 2 in panel mounted with a 2 in gap behaves a bit like a 3–4 in panel for bass.
More detail: how thickness changes what a panel absorbs.