Slat panels: decoration or acoustics? How they really work

Slat panels – vertical wooden battens on felt – have become one of the most popular wall features of recent years. They are often sold as "acoustic panels". Sometimes that is true; sometimes only to a small degree. In this guide we explain what decides whether a slat panel will actually improve the acoustics of a room.

What a slat panel is made of

A typical slat panel has three layers:

• slats – narrow strips of wood or board, set with gaps between them,
• felt – usually polyester, about 1 cm thick, to which the slats are glued or screwed,
• whatever is behind the felt – and this is where the differences begin.

Many off-the-shelf slat panels have nothing behind the felt: the panel is glued or screwed straight to the wall. Better solutions put a layer of mineral wool behind the felt, and the whole thing has a frame or is mounted on battens with a gap from the wall.

What the slats do, and what the felt does

The slats themselves reflect sound – they are hard wood. Sound only gets inside the panel through the gaps between them. The larger the share of the surface that is gaps, the more sound reaches the inside. In our panels the slats are 27 mm wide and the gaps 13 mm, so the gaps make up roughly a third of the front.

Felt about 1 cm thick is a thin porous material. It absorbs high frequencies, but in the speech range – and even more so below it – it does little. So if the wall comes straight after the felt, a slat panel improves the acoustics about as much as a thin layer of fabric would: it reduces sharp echo a little, but changes little about the reverberation you hear on calls and at the table.

The real work is done by what lies further in: a thick layer of wool, or an air space behind the felt. Sound passes through the gaps and the felt, then loses its energy in the wool. That is why the most important question when choosing slat panels is: what is underneath?

What to watch for in technical data

Makers of slat panels often quote impressive absorption figures. It is worth checking how they were measured. Sometimes the measurement was made with a layer of mineral wool behind the panel, or with a gap from the wall, while the panel is sold to be mounted straight onto the wall with nothing behind it. The same panel in those two set-ups absorbs very differently.

If the product sheet does not say what was behind the panel during the measurement, treat the result with caution.

How our slat panel is built

Inside, our slat panel is the same panel as the fabric version: a solid wood frame, 5 or 10 cm of stone wool and a veil on the face. Instead of fabric on the front there is 9 mm felt and 27 × 12 mm slats with 13 mm gaps, screwed through the gaps into the top and bottom rails of the frame. The sides are raw, sanded frame wood.

In the speech range and below, the wool decides, so here the slat panel behaves much like a fabric panel of the same thickness. In the high frequencies the slats reflect and scatter some of the sound. That is not a flaw: it means a room with many panels does not sound dead but keeps its natural brightness. We do not yet have our own laboratory measurements of the slat panels – we describe how they work from how they are built, and will add measurements once we have them.

The slats come in natural oak, walnut, black and white; the felt in black or grey. We make the panels in ready-made sizes: 60 × 120, 60 × 180 and 120 × 120 cm, 5 or 10 cm thick. You will find them all on the slat panels page.

Slat panel or fabric panel

Both absorb similarly in the speech range. They differ in looks and in what happens to the high frequencies.

Choose a fabric panel when:

• you want maximum absorption across the whole range, for example for voice recording or a voice-over corner,
• you want a colour matched to the wall, or a contrast in a particular shade,
• you want your own artwork or logo on the panel.

Choose a slat panel when:

• the panel should be a clear part of the interior, like a piece of furniture – in a living room, bedroom or reception,
• many panels will go into the room and you do not want it to sound too dry,
• you like wood and want the wall to go with the floor, the table or the cabinet fronts.

In practice a mix works well: slat panels where they are on show, fabric panels at the first reflection points and wherever the most absorption is needed. We explain how to plan the whole room in the guide to panel placement.

How many slat panels

Count the same way as for fabric panels: what matters is the total area, and the floor area is the starting point. For a living room or bedroom, panels covering 15–25% of the floor area are usually enough; for an office, 25–35%. You will find details and examples in how many acoustic panels do I need.

Remember that slat panels – like all acoustic panels – improve the sound inside a room but will not soundproof it from the neighbours. We explain the difference in soundproofing vs acoustic treatment.