Thicker panels absorb lower frequencies. The right thickness depends on what you are trying to control in bedrooms: mostly voices, the TV, and noise from outside the room.
| 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 bedrooms: 1 in. Speech is the main concern, and thinner panels sit tight to the wall, cost less and resist damage.
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.