{"id":2737,"date":"2026-07-21T12:16:01","date_gmt":"2026-07-21T10:16:01","guid":{"rendered":"https:\/\/stage.dekozell.de\/?p=2737"},"modified":"2026-09-25T12:23:52","modified_gmt":"2026-09-25T10:23:52","slug":"reverberation-time","status":"publish","type":"post","link":"https:\/\/dekozell.de\/en\/reverberation-time\/","title":{"rendered":"Reverberation Time"},"content":{"rendered":"

<\/p>\n

\n
Fundamentals & Standards<\/div>\n

Reverberation time and DIN 18041 explained clearly<\/h1>\n
\n
\nAuthor:<\/strong> Thomas Neubauer, Managing Director of DEKOZELL, has 20 years of experience in the development and application of acoustic plaster. He personally reviews and takes responsibility for every article.<\/div>\n
\n21 July 2026<\/span>
\n<\/span>
\n9 min read<\/span><\/div>\n<\/div>\n
\"\"<\/p>\n

Good room acoustics means one thing above all: hearing better.<\/figcaption><\/figure>\n

When it comes to professional acoustics, two terms come up again and again: reverberation time and DIN 18041. They may sound technical, but they are easy to understand. Even the seemingly mysterious decibel is actually quite simple once explained.<\/p>\n

Decibels in brief<\/b>Decibels express a ratio, which means a small numerical change can represent a large difference. Around 10 decibels less sounds roughly half as loud. Doubling the sound energy, on the other hand, increases the level by only around 3 decibels. Once understood, the principle is surprisingly simple.<\/div>\n

With our DEKOZELL\u00ae Acoustic Calculator<\/a> you can skip all the logarithmic charts in DIN 18041: with just a few inputs, you can go directly from room volume to the required acoustically open window and the appropriate reverberation time. These two values provide concrete acoustic targets for every type of room, from schools to concert halls.<\/p>\n

Once you understand the principle, you gain much more freedom when planning future projects. Architecture should be designed for the ears as well as the eyes.<\/div>\n
<\/span><\/p>\n

What reverberation time actually means<\/h2>\n<\/div>\n

<\/p>\n

Reverberation time describes how long a sound continues to linger in a room. It is measured as the time it takes for the sound level to fall by 60 decibels, hence the abbreviation T or RT60. The longer this value, the more reverberant the room.<\/p>\n

\"Reverberation
Reverberation time is the time it takes for the sound level to fall by 60 decibels after the source has stopped. The flatter the curve, the longer the reverberation remains in the room.<\/figcaption><\/figure>\n
Try it yourself<\/b>Clap your hands loudly once and count the seconds: \u201cone, two, three\u201d. If the reverberation only fades away around \u201cthree\u201d, the reverberation time is roughly 3 seconds \u2013 already very reverberant, like a large church. As a rule of thumb, from around 0.7 seconds upwards we usually perceive a room as noticeably reverberant; below that it tends to sound calm and clear. Try clapping your way through everyday spaces for a few days, from the bathroom to the stairwell. You will be surprised how quickly you develop a feel for how reverberant a room is. And don’t worry: if you ever find yourself travelling with a group of room acousticians, they all clap.<\/p>\n<\/div>\n

\"\"<\/p>\n

A reverberation time that is too long makes speech difficult to understand, while one that is too short can make a room sound \u201cdead\u201d. The aim is therefore not to eliminate reverberation entirely, but to achieve the right value for the intended use.<\/p>\n

<\/span><\/p>\n

Why the right reverberation time matters<\/h2>\n<\/div>\n

Reverberation time directly affects speech intelligibility. In a classroom or meeting room with excessive reverberation, listeners have more difficulty understanding individual words, concentration drops and speakers have to strain their voices more. In a concert hall, by contrast, a certain amount of reverberation is desirable so that music sounds full and warm. The right value therefore depends on what the room is intended for.<\/p>\n

From our experience<\/b>Design the permanently installed absorption \u2013 in other words, the acoustic plaster \u2013 so that on its own it already brings the room at least to the slightly more lively reverberation time suitable for music. Furnishings will then reduce the reverberation further, creating a pleasant living environment. Anyone who simply hopes that furniture alone will solve the problem later may be in for an unpleasant surprise and end up having to retrofit visible acoustic panels that interfere with the design concept. Aesthetics and acoustics are best planned together from the outset.<\/div>\n
<\/span><\/p>\n

What DIN 18041 specifies<\/h2>\n<\/div>\n

DIN 18041 is the key standard for audibility in rooms. It distinguishes between two basic groups and derives target values according to room volume and intended use.<\/p>\n

In the standard, these target values are read from logarithmic diagrams, matching a specific room volume with the corresponding reverberation time. A much easier way is to use our DEKOZELL\u00ae Acoustic Calculator<\/a>: it uses the same DIN 18041 formulas in the background, but directly returns the required acoustically open window \u2013 in other words, the area that needs to absorb the sound.<\/p>\n

Where this absorption area ultimately comes from \u2013 acoustic plaster or another solution \u2013 is up to you as the designer. Our calculator is deliberately manufacturer-neutral. Freely available tools like this are rare, because most online calculators are tailored to a particular supplier’s products and therefore restrict planning freedom. What matters most is that acoustics are considered from the very beginning, regardless of which solution ultimately provides the absorption.<\/p>\n

Group A: Rooms for communication<\/h3>\n

This group includes rooms where speech and communication are the priority, such as classrooms, meeting rooms, lecture halls or courtrooms. For these spaces, the standard defines a target reverberation time based on room volume and type of use. As a general rule, the more important speech intelligibility is, the shorter the required reverberation time.<\/p>\n

Group B: Rooms requiring noise control<\/h3>\n

This group includes rooms where the main concern is not presentations but limiting noise, such as open-plan offices, canteens, foyers or workshops. Instead of specifying an exact target reverberation time, the standard defines requirements for the amount of absorbing surface relative to the room.<\/p>\n

Special case: Sports halls and swimming pools<\/h3>\n

DIN 18041 treats sports halls and swimming pools as a special case: large volumes, many hard surfaces and often several groups using the space at the same time create particular acoustic demands. If events with an audience take place, the hall is acoustically treated as a speech space because announcements need to remain intelligible. Without an audience, the standard distinguishes between different types of use, shown in the DEKOZELL\u00ae Acoustic Calculator as Sport 1 and Sport 2:<\/p>\n