Good acoustics with Troldtekt

Choose an effective acoustics solution.

Photo: Tommy Kolsior

Sounds in a room are reflected off the walls and ceilings, and these reflections make up most of the sounds we hear. If we want to be able to talk and clearly hear what others are saying, it is vital that the reverberation time in the room is short – that the sound in the room ‘dies out’ quickly.

You can significantly reduce reverberation time by choosing a Troldtekt acoustic solution. While a concrete ceiling absorbs only 1–2 per cent of the sound, a Troldtekt ceiling will typically absorb 80–90 per cent.

Design matters

The different structures with Troldtekt acoustic panels yield different results for reverberation time.

For the best possible acoustic effect in residential properties, install Troldtekt acoustic panels directly beneath the 200–300 mm mineral wool and vapour barrier ceiling structure. However, installing Troldtekt under an existing ceiling may also be a viable solution.

In project buildings such as large offices, schools, institutions and other premises with special acoustic requirements, the optimum solution is usually to install a suspended Troldtekt ceiling in a profile system which hangs 200–300 mm below the fixed ceiling, so that there is a cavity above the acoustic ceiling.

Easy installation with two-layer panel

If you choose Troldtekt Plus, the mineral wool is glued to the back of the actual panel, making it much easier for tradespeople to handle compared to loose mineral wool.

Troldtekt Plus acoustic panels have an installation height of only 43 mm, and provide very effective sound absorption in rooms which do not have space for a 200–300 mm cavity between the acoustic panels and the ceiling.

See sound measurements for different constructions with Troldtekt 

Paint your panels without compromising acoustics

Troldtekt acoustic panels can be painted again and again with a paint sprayer without compromising their acoustic properties. This can help extend the lifetime of the panels – for example during renovations, and if a building changes owner or tenant.

Photo: Tommy Kosior, Troldtekt A/S

See how big a difference Troldtekt makes

Daniel Boje and his family moved to a brand new house south of Aarhus. Shortly after moving in, they realised there was something wrong with the acoustics. Sounds were bouncing around the rooms, even though there were sound-absorbing plasterboard ceilings many places in the house.

This example shows how, after installing Troldtekt acoustic panels on the ceilings, the family got the house they dreamed of. Professional sound measurements before and after show that the reverberation time in the kitchen/family room and bathroom have decreased by up to 60 per cent. And it has made a difference you can hear.

Read more about the home in Solbjerg

Recommended reverberation times

The reverberation time in a room should suit both the size and purpose of the room. For example, in classrooms short reverberation times are needed to ensure that pupils can hear what the teacher is saying – on the other hand, the sound shouldn’t fade away so quickly that not everyone in the room can hear what the teacher is saying.

The reverberation time should ideally be about the same across the entire frequency range. In concert halls designed for classical music, however, a slightly longer reverberation time for the lower frequencies is preferable.

The table shows Troldtekt’s recommended reverberation times for different room types.


Room type

Reverberation time in seconds

Sound control rooms

0.2–0.3 sec.

Sound studios

0.4–0.6 sec.

Kitchen/living rooms

0.4–0.5 sec.


0.4–0.8 sec.

Daycare institutions

0.4 sec. (requirement)


0.6 sec. (requirement)

Small offices/meeting rooms

0.6 sec.

Larger offices

Absorption area (A) should be greater than 1.1 x floor area

Patient and treatment rooms

0.6 sec.


0.6 sec.

Rock music venues

0.7–1.0 sec.


1.1–1.4 sec.

Opera houses

1.5–1.7 sec.

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