The house is bright, open and exactly as you dreamed of. But when the family gathers for dinner, every voice, every piece of cutlery and every chair being pulled out fills the entire room. Conversations require more energy, and after a dinner party, you are tired in a way that is hard to put into words. This is reverberation, and it is one of the most widespread sound problems in newer and renovated Danish homes.
The good news is that reverberation is a problem that can be solved without remodelling. It simply requires understanding why it occurs and where in the room it is most effective to address it.
What is reverberation?
Reverberation is the sound that remains in a room after the sound source has stopped, because the sound is reflected back and forth between the room's hard surfaces. When someone speaks, the sound first hits the ceiling, walls and floor, and if the surfaces are hard, it is sent on instead of being absorbed. The reflections overlap with each other and with new sound, resulting in a room where everything sounds slightly louder and slightly muddier than it should.
Reverberation, reverberant sound and echo are often used interchangeably, but there is a difference. Reverberant sound is essentially the same as reverberation, meaning the overall sound that rings out in the room. An echo is a single, distinct repetition of sound, typically heard in large rooms or outdoors, when the reflection arrives so late that the ear perceives it as an independent sound. In an ordinary home, it is almost always reverberation that is the problem, not echo.
If you want to know more about how an acoustic ceiling works with sound, our article on what an acoustic ceiling is explains the principle behind absorption.
Why do newer houses reverberate more?
What makes modern homes beautiful is often the same thing that makes them acoustically harsh. Large glass sections provide light and views, but glass reflects almost all the sound that hits it. Plank flooring, tiles and microcement are durable and attractive, but they have the same effect. Smooth plasterboard ceilings and white walls create a calm look, but they send sound directly back into the room.
An open floor plan amplifies the problem because sound no longer stops at a wall. The kitchen, dining area and living room become one large sound space, where the dishwasher, conversation and television blend together. High ceilings and vaulted ceilings make the room larger, and the greater the air volume, the longer it takes for sound to die away. We have written more about the special conditions of acoustic ceilings for vaulted ceilings, where sloping surfaces send sound in unpredictable directions.
Finally, the interior design also plays a role. The Nordic, minimalist style with few textiles, bare floors and open surfaces looks fantastic in pictures, but there is very little in the room that can absorb sound. In a newly built standard house in Silkeborg, the family experienced precisely that combination, where hard plasterboard ceilings and high ceilings in the open-plan kitchen and living area created significant reverberation that made everyday life unsettled.
How to tell whether your room has too much reverberation
You do not need measuring equipment to assess whether reverberation is a problem. There are a couple of simple tests you can do yourself.
The clap test is the quickest. Stand in the middle of the room and clap your hands hard once. Listen to what happens afterwards. In a room with pleasant acoustics, the sound dies away almost immediately. In a room with a lot of reverberation, it hangs in the air, and you can often hear a faint, fluttering trailing sound between parallel surfaces such as the floor and ceiling.
The conversation test is the most relevant for everyday life. Notice whether you unconsciously raise your voice when several people are talking at the same time at the dining table, or whether you have difficulty following a conversation at the other end of the room. If dinner parties feel more exhausting in your home than at a restaurant, reverberation is a likely cause.
You can also record a short conversation with your phone in the middle of the room and listen to it afterwards. The microphone does not distinguish between sound and reverberation in the same way as the brain does, so reverberation often becomes clearer in the recording than it is in reality.
Reverberation time and what is a good value in a home
Reverberation is measured as reverberation time, which is the time it takes for sound to decrease by 60 decibels after the sound source has stopped. The shorter the reverberation time, the clearer and calmer the sound is perceived in the room.
As a rule of thumb, a reverberation time of around half a second is perceived as comfortable in an ordinary living space. A sparsely furnished room with hard surfaces can easily exceed one second, and that is when you start to notice that conversations become tiring. The exact figure depends on the size and use of the room, so the values should be read as a guideline, not as a definitive answer.
Reverberation time is also part of the building regulations. BR18 requires that reverberation time be taken into account when planning new construction, that homes must comply with sound class C in the DS 490 standard, and that rooms' reverberation time must be regulated according to their use. The building regulations therefore set a framework for construction, but they are no guarantee that a finished and furnished room with glass, hard floors and smooth ceilings feels comfortable to spend time in. This is largely something you can influence yourself.
Where in the home is reverberation most pronounced?
The open-plan kitchen and living area is almost always the room where reverberation is worst. It is the home's largest room, has the most hard surfaces, and is where the most sound sources are active at the same time. The living room typically comes right after, especially if it has an open connection to the kitchen or extra ceiling height.
Entrance halls and stairwells are small rooms, but they often have stone floors, bare walls and no furniture, and can therefore reverberate surprisingly much. The bathroom is acoustically the harshest room in the house, but because you rarely spend long periods there or hold conversations, it bothers very few people.
We have created a more detailed review of which rooms benefit most from a solution, and how much coverage each room typically requires, in our guide to acoustic ceilings in the home.
How to reduce reverberation
Reverberation is reduced by adding surfaces to the room that absorb sound instead of reflecting it. The question is simply how much absorbing surface is needed and where it does the most good.
Textiles are the first thing most people think of. A large rug, thick curtains and an upholstered sofa all help, and in a room with slight reverberation, that may be enough. The problem is that they rarely cover a sufficient surface area to make a real difference in a large, open room with high ceilings. Curtains only cover the windows when they are drawn, and a rug only covers part of the floor.
The ceiling is therefore the most effective place to do something. It is the largest uninterrupted surface in almost all rooms, it is not used for furniture or pictures, and it is located above the entire area where sound occurs. By covering 30 to 50 percent of the ceiling surface with acoustic panels, you can noticeably reduce reverberation without changing the room's layout or function.
ARKU’s acoustic panels in PET felt are developed for precisely this task. The panels weigh around 2 kg per m², are 12 mm thick and are glued directly onto the ceiling you already have. They require no acclimatisation and can be installed as soon as they are unpacked, and most people can complete an ordinary room in an afternoon. Read more about installation on an existing ceiling, or see formats and colours in our range.
Reverberation is not the same as noise from the neighbour
It is important to distinguish between sound that occurs in the room and sound that comes from outside. Reverberation is about how sound behaves inside the room where it occurs. If what bothers you is impact noise from the floor above, voices from the neighbour or traffic from the street, it is a question of sound insulation, and it cannot be solved with acoustic panels. We explain the difference in the article about acoustics and sound insulation.
