How many sound absorbers do you need?

Creating a pleasant acoustic environment is about understanding how much sound-absorbing material is needed to effectively reduce reverberation and unwanted sound reflections. By using the right amount of sound absorbers, you can improve the acoustics in everything from offices and schools to restaurants and home environments. With our reverberation time calculator, you can easily determine how much surface area should be covered to achieve a more comfortable and subdued acoustic environment.

The goal of sound absorption is to reduce echoes and noise without creating an overly muffled sound environment. A good guideline is to cover at least 20–30% of the room’s total surface area, but in some cases, more may be needed depending on the room’s size, choice of materials, and sound issues. The ceiling is often an ideal place to start with sound absorption, as it is a large, unobstructed surface where sound waves are highly reflected. Walls and corners are also important areas to focus on to achieve even sound distribution.

The installation of sound absorbers can be tailored to the room’s needs and aesthetic requirements. For a visible installation, brackets and mounts can be used on both walls and ceilings. If you prefer a more discreet solution, there are hidden mounting options that blend into the room. Wire systems offer a flexible solution for ceiling mounting, while Velcro strips can be a convenient option for walls where you want a removable solution. For corner mounting and diagonal placements, there are specially designed brackets that help create effective and balanced sound absorption throughout the room.

By carefully planning the placement and quantity of sound absorbers, you can create harmonious and pleasant acoustics that improve both the work environment and well-being. Use our calculator to get an exact estimate of how many sound absorbers you need for your specific room.

Calculate the reverberation time in your room and optimize the acoustics

Understanding the reverberation time in a room is crucial for creating an optimal acoustic environment. Reverberation time describes how long a sound continues to be heard after the sound source has fallen silent. By calculating this time, you can get a clear picture of how much sound absorption is needed to reduce echoes and improve the room’s acoustics.

With our tool, you can easily calculate the reverberation time and tailor sound-absorbing measures to the room’s specific needs. By optimizing the acoustics, you create a more pleasant environment where speech intelligibility is improved and sound levels are better balanced. This is particularly important in office environments, conference rooms, schools, and homes, where a clear and comfortable sound environment is crucial for productivity and well-being.

How much sound absorption is needed?
To achieve balanced acoustics, it is recommended that at least 20–30% of the room’s surface area be covered with sound absorbers. The ceiling is an ideal place to start with sound absorption, as it often offers the largest surface area free of furniture or other obstacles. Installing sound absorbers on the ceiling significantly reduces reverberation, leading to a more subdued and pleasant sound environment.

If you want to further improve the acoustics, the walls can also be covered with sound absorbers. Strategic placement where sound reflections are strongest provides the most effective sound attenuation. By combining ceiling and wall absorption, you can create a more controlled sound environment without disruptive echoes.

Installation Options for Sound Absorbers
To ensure a smooth installation that suits various room environments, we offer several mounting options. Ceiling absorbers can be installed using a wire system, visible brackets, or vertical brackets for suspended ceilings. If a more discreet installation is desired, wire mesh baskets can be used to create a stylish and functional solution.

For wall mounting, sound absorbers can be attached using visible brackets or concealed mounting hardware for a minimalist look. Velcro strips can also be used for flexible and easy installation. If you want to cover corners or diagonal surfaces between the ceiling and wall, special brackets and diagonal mounting options are available to maximize sound absorption in hard-to-reach areas.

Improve the sound environment with the right acoustic solution
By calculating the reverberation time and adjusting the room’s sound absorption, you can create a more comfortable and functional environment where sound levels are balanced and echoes are minimized. Whether you’re optimizing an office, a home environment, or a larger public space, it’s important to choose the right combination of sound absorbers and mounting solutions.

With our flexible mounting options and high-performance sound absorbers, you can easily tailor the acoustics to your needs. By covering the right surfaces and using a well-planned installation, you can create a harmonious sound environment that improves both productivity and well-being.

Calculate the reverberation time

Acoustic Test: Before and After with PES Sound Absorbers

The test was conducted in a 24 m² studio measuring 4 x 6 meters. A total of 4.026 m² of SilentDirect PES sound absorbers were installed in the room, which corresponds to approximately 16.8% of the floor area. The absorbers were placed on both the ceiling and the walls to reduce echo, reverberation, and harsh sound reflections.

Products used in the test:

1 unit SilentDirect PES Ceiling, 800 x 800 mm
2 SilentDirect PES Wall, 800 x 800 mm
6 SilentDirect PES Wall, 592 x 592 mm

What is reverberation time, and why is it important?

Reverberation time is a measure of how long a sound continues to be heard in a room after the sound source has fallen silent. It is defined as the time it takes for the sound level to decrease by 60 decibels and is measured in seconds. Reverberation time plays a crucial role in how we perceive the sound environment and affects everything from speech intelligibility to musical experiences.

A room with a long reverberation time can create an echoing and unbalanced sound field, making it difficult to understand speech clearly. This can be particularly problematic in classrooms, conference rooms, and work environments where communication needs to be clear and distinct. On the other hand, a reverberation time that is too short can make the sound experience feel muted and lifeless, which can be undesirable in, for example, concert halls where a certain amount of reverberation is desirable to give the music a richer tone.

What factors influence reverberation time?

The reverberation time in a room is influenced by several factors, with the room’s size, shape, and choice of materials being crucial. Larger rooms with high ceilings tend to have longer reverberation times because sound waves have more space to reflect before they are dampened. The room’s surfaces also play a major role—hard materials such as concrete, glass, and tile reflect sound, which prolongs the reverberation time. Soft and porous materials such as carpets, curtains, and sound-absorbing panels, on the other hand, help reduce reverberation by absorbing sound waves instead of reflecting them.

The room’s furnishings also affect the acoustic environment. A minimalist room with many hard surfaces will have a longer reverberation time compared to a room with plenty of textiles, upholstered furniture, and sound-absorbing elements. By strategically placing sound absorbers on ceilings, walls, and in corners, the reverberation time can be optimized to create a more pleasant and balanced acoustic environment.

Optimal reverberation time for different rooms and spaces

Reverberation time is a crucial factor in the acoustic environment of various types of rooms and spaces. By adjusting the reverberation time to suit the room’s intended use, you can improve speech intelligibility, reduce distracting noise, and create a more pleasant atmosphere.

Office Environments – Creating a Productive Work Environment
In offices and meeting rooms, the reverberation time should be kept relatively short, typically between 0.4 and 0.8 seconds. A reverberation time that is too long can lead to increased noise levels, which negatively affects concentration and productivity. In open-plan offices where sounds from conversations, keyboards, and other sources easily spread, it is particularly important to maintain a controlled reverberation time. By using sound absorbers on ceilings and walls, you can reduce reflections and create a more focused work environment.

Educational Environments – Improved Speech Intelligibility and Learning
In classrooms, lecture halls, and auditoriums, a reverberation time of 0.4 to 0.6 seconds is optimal. A shorter reverberation time improves speech intelligibility and reduces distractions from background noise, making it easier for students to focus. Excessively long reverberation times can make it harder to hear the teacher’s voice, which impairs learning. By combining ceiling absorbers and wall panels, acoustics can be optimized for clear communication.

Residential – Create a Cozy and Calm Atmosphere
In living rooms, dining rooms, and bedrooms, a reverberation time between 0.5 and 0.9 seconds is often ideal. This level contributes to a pleasant sound environment without making the sound feel too muffled or lifeless. In kitchens and bathrooms, where hard surfaces such as tile and stone dominate, a slightly shorter reverberation time of 0.5 to 0.8 seconds can reduce harsh sound reflections and create a more harmonious sound environment.

Public Spaces – Balance Between Liveliness and Clarity
In airports and train stations, the reverberation time should be between 0.9 and 1.5 seconds. This level ensures that announcements and communication are heard clearly while the soundscape remains natural. Shopping centers should have a reverberation time between 1.3 and 2.0 seconds to create a pleasant atmosphere where the sound level is kept at a manageable level.

Healthcare Facilities – A Calming Acoustic Environment for Patients and Staff
In patient rooms, a short reverberation time of 0.4 to 0.6 seconds is preferable to minimize disruptive noise and create a calming environment. Hallways and waiting rooms can have a slightly longer reverberation time, between 0.6 and 1.0 seconds, to balance the acoustic environment without creating a feeling of isolation. In treatment and examination rooms, the reverberation time should be between 0.4 and 0.8 seconds to ensure clear communication between healthcare staff and patients.

Industrial Environments and Warehouses – Safety and Clear Communication
In warehouses, a reverberation time between 0.6 and 1.0 seconds is appropriate to reduce noise levels and improve speech intelligibility among staff. In industrial environments where machinery generates high noise levels, it is especially important to control the reverberation time—typically between 0.6 and 1.0 seconds—to protect workers’ hearing and create a more ergonomic work environment.

Studios and Movie Theaters – Precise Sound Control
In podcast and radio studios, the reverberation time should be between 0.4 and 0.6 seconds to ensure that speech remains clear and distinct without unwanted reflections. Music studios used for recording instruments and vocals should have a reverberation time between 0.6 and 1.2 seconds, depending on the musical style. Mixing and mastering studios require shorter reverberation times, between 0.2 and 0.5 seconds, to provide an accurate reproduction of the sound.

Theaters, movie theaters, and concert halls – Create an optimal listening experience
In theaters and movie theaters, the reverberation time should be between 0.9 and 1.2 seconds to balance speech intelligibility and the overall sound experience. Concert halls used for classical music should have a reverberation time of 1.6 to 2.2 seconds to give the music a rich, full sound. Pop and rock music benefit from a shorter reverberation time, between 1.0 and 1.5 seconds, to maintain a clear and dynamic sound image.

Churches and Chapels – Amplification of Music and Speech
In larger churches, a reverberation time between 1.8 and 4.0 seconds is common, depending on the room’s design and use. A longer reverberation time enhances choral singing and organ music, but excessively long reverberation times can make speech difficult to understand. By balancing sound absorption and diffusion, an optimal acoustic environment can be created.

Summary and Acoustic Optimization
The optimal reverberation time varies depending on the room’s purpose and the activities carried out there. By using sound absorbers in strategic locations, you can adjust the reverberation time and create acoustics tailored to the room’s needs. Ceiling absorbers, wall panels, and corner absorbers can all play a crucial role in optimizing the acoustic environment.

Reverberation Time in Rooms Without Sound Absorbers – Why Sound Becomes a Problem

When a room lacks specific sound-absorbing materials, sound waves tend to be reflected to a high degree. The absorption capacity of the room’s surfaces is low, especially if they consist of hard materials such as concrete, glass, or untreated wood. These materials generally have very low absorption coefficients, which means they absorb almost no sound at all. Instead, sound bounces back and forth between the surfaces, creating a long reverberation time and a sound environment that feels echoey and noisy.

In rooms where no sound absorption is installed, the reverberation time can be significantly longer than is desirable for a comfortable acoustic environment. The longer the reverberation time, the more difficult it becomes to hear and understand speech, which affects both concentration and well-being. This is particularly problematic in workplaces, schools, and public spaces where clear communication and focus are essential.

Common Materials and Their Low Absorption Capacity
Hard and smooth materials reflect sound rather than absorbing it, causing sound to bounce between walls, floors, and ceilings. Here are some examples of typical absorption coefficients for common surfaces in a room without sound absorbers:

Concrete walls
Concrete walls have a sound absorption coefficient of about 0.01 to 0.10, which means they reflect almost all sound.

Glass windows
Glass windows absorb only about 0.05 of the sound waves, making them ineffective at reducing reverberation.

Hardwood
Hardwood, such as untreated wooden floors or wall panels, has an absorption coefficient between 0.05 and 0.15, making it slightly better than concrete but still insufficient for a good acoustic environment.

Brick walls
Brick walls absorb sound even less effectively, with a coefficient of about 0.02 to 0.05.

Painted drywall
Painted drywall has an absorption coefficient between 0.05 and 0.10, meaning it contributes only marginally to sound attenuation.

These figures clearly show that a room without sound-absorbing materials will have a very long reverberation time and a poor acoustic environment. This means that speech becomes difficult to make out, sound levels can feel stressful, and echoes become a source of disturbance.

Consequences of a Long Reverberation Time in Rooms Without Sound Absorbers

In a room where all surfaces consist of hard materials and no sound absorption has been installed, the reverberation time can become extremely long. This means that sound continues to bounce around the room for several seconds after the sound source has fallen silent. Such an acoustic environment affects productivity, well-being, and health.

Reduced concentration and work performance
In work environments, it becomes harder to focus when noise levels are high and echoes amplify distracting sounds. Sounds from conversations, keyboards, and other office noises can overlap and create a stressful soundscape.

Impaired communication
In schools and meeting rooms, it becomes harder to understand speech due to reflected sound waves. This negatively affects students’ learning and can also lead to misunderstandings in work meetings.

Increased stress and fatigue
A long reverberation time can create a stressful acoustic environment that contributes to mental fatigue and increased stress levels. Prolonged exposure to a noisy environment can also negatively affect hearing.

Poor sleep quality
In homes, echoing sounds can make it harder to relax and sleep. This is especially true in bedrooms with hard surfaces, where sounds from other rooms can be amplified.

How to Improve the Acoustic Environment in a Room Without Sound Absorbers
To reduce reverberation time and create a more pleasant acoustic environment, the room needs to be equipped with sound-absorbing materials. An effective solution is to install sound absorbers on the ceiling, walls, and other strategic surfaces. The ceiling is particularly important because it constitutes a large reflective surface and often has ample space for sound-absorbing materials. Another important measure is to cover at least 20–30% of the room’s surfaces with sound absorbers. This significantly reduces echoes and creates a more controlled acoustic environment. Wall panels, acoustic ceilings, carpets, and textiles can also help dampen sound waves and create more pleasant acoustics. By understanding how hard surfaces affect the acoustic environment and taking steps to absorb sound reflections, you can create a more comfortable space that is optimized for communication, work, and well-being.

Placement of Sound Absorbers – Optimizing Acoustics for a Better Sound Environment

Placing sound absorbers in the right spots in a room is crucial for creating pleasant and well-balanced acoustics. Once you’ve identified how much surface area needs to be covered to reduce reverberation and disruptive noise, the next step is to determine where to place the sound-absorbing materials. By strategically choosing the right locations, you can maximize the effectiveness of sound absorption and create an environment where the sound is clear, pleasant, and free of echoes. One of the most effective places to start is the ceiling, as it is often an unused surface where sound can reflect freely. Installing sound absorbers on the ceiling helps reduce reverberation and creates a more controlled acoustic environment. In addition to the ceiling, corners and walls are important areas for sound absorption, especially if the room has many hard surfaces such as concrete, glass, or wood.

Ceiling Sound Absorption—The Most Effective Placement

Installing sound absorbers on the ceiling is one of the most effective ways to reduce sound reflections and create a controlled acoustic environment. There are several different installation methods depending on the room’s conditions and desired aesthetics. Ceiling mounting with brackets is a common solution where sound absorbers are attached directly to the ceiling, either flush-mounted or with a small gap to improve sound absorption. An alternative is diagonal mounting, where absorbers are placed between the ceiling and the upper part of the wall. This method is particularly effective for absorbing low-frequency sound waves that often accumulate in these areas. For even better sound absorption, sound absorbers can be suspended from the ceiling using wires. The lower the absorbers are placed, the more effective the sound absorption becomes, as they capture sound waves from multiple directions. Another effective method involves vertically suspended absorbers, where sound-absorbing panels hang freely in the room. This is a highly effective solution for reducing reverberation and creating more balanced acoustics. In environments where sound absorbers are subject to wear and tear or risk of damage—such as industrial or public spaces—wire mesh baskets can be used. These protect the sound absorbers while providing effective sound absorption.

Corner Absorbers – Ideal for Managing Low-Frequency Sound

Sound absorbers placed in corners—also known as bass traps or corner absorbers—are particularly effective at managing low-frequency sound waves. Since corners are often areas where sound is reflected and accumulates, a properly placed bass trap can reduce resonances and create a more balanced acoustic environment. Bass traps are not only effective but also space-saving, as they are placed in areas that are otherwise rarely used. For rooms with significant bass issues, such as music studios and movie theaters, corner absorbers are an essential measure for achieving optimal acoustics.

Wall-mounted sound absorbers—improve the sound environment and reduce reflections

Wall-mounted sound absorbers are one of the most flexible solutions for reducing reverberation and creating a quieter, more pleasant sound environment. There are several mounting options depending on the room’s needs and aesthetic preferences. For a traditional installation, brackets can be used to attach the absorbers directly to the wall. For a more discreet installation, hidden mounting brackets can be used, providing a seamless and stylish finish. Another practical solution is to use Velcro strips, which make it easy to adjust or replace absorbers as needed. In certain environments, such as industrial facilities or public spaces, sound absorbers can be placed in wire baskets and screwed to the wall. This provides extra protection and prevents the absorbers from being damaged or worn down. To maximize the effectiveness of wall-mounted sound absorbers, they should be placed on strategic surfaces where sound is most likely to be reflected. This includes areas near sound sources, such as speakers and workstations, as well as parallel walls where sound waves easily bounce back and forth.

Strategic Placement for Maximum Effect

By placing sound absorbers on ceilings, walls, and in corners, you can optimize the acoustic environment and reduce disruptive reverberation. The ceiling is one of the most effective places to start, as it is often a large reflective surface that can contribute to a long reverberation time. Wall-mounted absorbers help dampen sound reflections and improve acoustics, while corner absorbers are one of the best solutions for managing low-frequency sound.

By choosing the right mounting method and placing the absorbers in strategic locations, you can create a more balanced and pleasant sound environment, whether in an office, a studio, a public space, or a private home.

Did you know that…

Can a room have perfect sound insulation but still sound bad? Many people believe that if no sound gets in or out, the acoustics are good—but the reverberation time, that is, how long the sound bounces around the room, can be the real culprit behind an unbalanced sound environment.

Reverberation time is affected not only by the room’s size but also by its shape and the materials inside it. A small room with hard surfaces can have a longer reverberation time than a larger room with textiles and furniture. This is because sound waves that aren’t absorbed continue to bounce back and forth, creating a metallic, echoing sound.

You can calculate the reverberation time using a simple formula! Sabine’s formula, used in acoustic calculations, shows that the reverberation time (RT60) depends on the room’s volume and the amount of sound-absorbing material. The more sound-absorbing surfaces there are, the shorter the reverberation time—but too much absorption can instead make the room feel “dead” and unnaturally quiet.

So if you find that the sound in a room feels unpleasant, keep in mind that it’s not always about reducing the sound level—sometimes it’s the reverberation that needs to be controlled. And the right placement of absorbers can make all the difference!