How to Improve Interior Acoustics | DAMPA

DAMPA® is a Danish company specialised in the development and production of acoustic steel and aluminium ceilings, as well as acoustic wall panels for the building industry, with sales exclusively in the European market.

Good acoustics are critical to the experience of interior spaces, but many buildings have not been designed with this factor in mind. There are several solutions to improve the acoustics in a space. However, the most optimal solution depends on the use of the space and whether it is a new construction or an adjustment to an existing building.

How can we achieve good acoustics in existing buildings?

• There are three different options for improving acoustics: ceiling, wall, and furnishing
• The best solution depends on the current situation and needs
• DAMPA users can install a brand-new acoustic ceiling or try to upgrade the current acoustic ceiling with new/extra acoustic batts.
• Installing acoustic wall panels is often the most cost-effective solution.
• Furnishing with porous materials such as carpets and curtains only works to a limited extent.
• The higher the acoustic class is, the fewer acoustic elements are needed

Users can choose acoustic elements, which have been tested, and get expert advice, so you are assured that the investment in acoustic optimization pays off.

What are good acoustics?

• The Sound

Acoustics is an expression for, how sound moves and reflects in a room. Sound consists of pressure waves which move across the air. Good acoustics are characterized by how quickly the pressure waves abeyance. The pressure waves are calmed by the help of sound-absorbing materials. When DAMPA has a room only consisting of hard surfaces, as brick walls and concrete floor, the sound waves will be thrown around in the room for a long time before settling. When that happens, we talk about a long reverberation time, also known as echo.

• Reverberation Time

Theoretically speaking, when we talk about good or bad acoustics, we look at the reverberation time. The reverberation time is decided by how many seconds it takes for the sound to fall with 60 dB after the sound source has stopped. For example, if you are talking with a person in a room with a long reverberation time, the first spoken words will not die out before the next words come. It will therefore be hard to have a conversation. However, if enough absorbing materials are in the room to create optimal acoustics, users will get good speech comprehension.

• Sound-absorbing Materials

To regulate and lower the reverberation time we need elements, which can absorb sound so that it does not reflect in the room. The ability of elements to absorb sound is denoted by the absorption coefficient and is indicated by Alpha (a). As a starting point, it is desired that the sound-absorbing elements have an Alpha value as close to 1 as possible since the value 1 means that all sound sent towards the element is absorbed.

The closer to 1 the alpha value for a sound-absorbing element is, the fewer elements are needed in the room. It is important to create synergy between the function of the room and the sound-absorbing elements. For example, acoustic ceilings cover a large area, which is why many elements with a low alpha value can be ideal, to ensure that the reverberation time does not become too low.

Examples of Sound Absorbing Materials

Sound-absorbing materials can be incorporated into a room in various ways. DAMPA users can use both vertical and horizontal surfaces to create suitable and optimal acoustics.

Acoustic Ceilings: The ceiling is often ideal to use as a sound-absorbing element, as there is a large disposable surface, where sound-absorbing materials can be added.
Acoustic Wall Panels: In many cases, an acoustic ceiling is ideal, but when DAMPA has a room with a high ceiling, the sound-absorbing material will be far from the sound source.
Interior Design: Curtains, carpets, and upholstered furniture, along with other interiors, can also help reduce the reverberation time.

However, this will rarely be enough to achieve optimal acoustics, but it will supplement walls and ceilings. There are different acoustic needs depending on which room we are in. The reverberation time is an expression of, how quickly the sound falls by 60 dB.

To lower the reverberation time, users need to have acoustic elements in the room. Their ability to absorb sound is denoted by the absorption coefficient (alpha). The closer the alpha is to 1, the better the element is at absorbing the sound. The rule of thumb says that if you use acoustic wall panels, the walls must be covered corresponding to 20% of the floor area.

Three Ways to Improve the Acoustics

When talking about “bad” acoustics, it is usually caused by a long reverberation time, due to hard and sound-reflecting surfaces in the room. When the sound hits the surfaces, it will be reflected back and forth between the hard surfaces in the room, therefore, users will hear the echo and discover the bad acoustics.

To solve this problem, it is crucial to add sound-absorbing elements or materials to the room. In this case, the ceiling and walls are ideal to implement in the acoustic upgrade, while it is also often on these surfaces, you will get the best results.

1. Optimize the Acoustics Through the Ceiling

The ceiling is a big surface, which, specifically when talking about a suspended ceiling, is close to the sound source e.g., people talking. Therefore, this is an excellent surface to implement sound-absorbing elements. When talking about ceilings there are three possibilities:

• A New Comprehensive Acoustic Ceiling: Suppose the current ceiling is not an acoustic ceiling. In that case, the whole ceiling’s surface reflects the sound waves, which creates a long reverberation time and contributes to undesirable acoustical conditions. A new acoustic ceiling is an extensive cost-intensive solution when adjusting to an existing building. However, this is where you will get the best results.
• Upgrade Your Current Acoustic Ceiling: Suppose you have an acoustic ceiling, but it does not live up to the present acoustical requirements, it can be ideal to examine whether it is possible to make acoustical improvements to the existing ceiling. Such improvements can be e.g. done by placing extra sound-absorbing materials in the space above the acoustic ceiling. However, be aware to keep a part of the space above the ceiling, as this is essential when lowering the reverberation time in the lower frequencies.
• Use Acoustics Baffles: An acoustic baffle is a sound-absorbing element that hangs down from the ceiling. This is especially ideal in rooms that need acoustical improvements in specific areas. This could be a meeting room, where you add an acoustic baffle over the meeting table, to make it more comfortable and easier to hear, what the other people are saying. The acoustic baffle will not only have a positive effect on the acoustics around the meeting table but also the rest of the room.

2. Use the Walls to Upgrade the Acoustics

If it is not sufficient or possible to install an acoustic ceiling, acoustic wall panels can advantageously be installed. There are many acoustic solutions for the walls, which are easy to install and for a low cost.

The rule of thumb when creating optimal acoustic is that the walls must be covered with sound-absorbing material corresponding to approx. 10-20% of the floor area – the actual percentage does however depend on the location of the sound absorbers, their absorption class, and the composition of the room. The walls are often close to the sound source, especially in narrow spaces, and will thus provide an improving and noticeable effect.

3: Furnishing

It will have a positive effect on the acoustics when furnishing a room with porous materials e.g., carpets and curtains. However, the sound-absorbing effect is only a fraction of the effect achieved when using acoustic ceiling or wall panels.

Finally, optimizing the acoustics of a room can seem like a major renovation and cost-intensive. But it does not have to be. For example, sound absorbers can be added to ceilings and walls on an ongoing basis, depending on the specific needs.

There are many parameters to consider when it comes to optimizing the acoustics. It is therefore important that users get expert advice, so users are assured, that the solution solves the acoustics needs and to ensure that you do not end up with an incorrect placement of the wall panels or more sound-absorbing elements than a user needs.