Reverberation: what is it and how do you resolve it?
Many people confuse the words "reverberation" and "reverberation time". However, they do not mean the same thing. Reverberation is what you hear. Reverberation time is what you measure. In this blog, the acoustic we, the experts from EASY Noise Control, explain exactly what reverberation is, how you recognise it, and which solutions ensure a pleasant acoustic environment.
Birgit Brinks
What is 'reverberation'?
Reverberation occurs when sound hits hard surfaces and reflects multiple times. Think of walls, ceilings, windows, or a concrete floor. The sound waves continue to travel through the space and accumulate. As a result, the noise level increases in a room and the space sounds lively. Conversations overlap, words become indistinct, and a room quickly feels busy or noisy.
You often recognise echo in situations such as:
- Difficulty understanding during meetings
- A noisy restaurant despite a limited number of guests
- A classroom where pupils have trouble understanding each other
- A living room with many hard materials
- An office where phone conversations tend to linger
The more hard and smooth materials present, the greater the effect of reverberation.
What is the difference between reverberation and reverberation time?
Sleep onset latency and REM sleep latency are closely related, but they do not mean the same thing.
Reverberation is the experience
Reverberation is what people hear and experience. A space sounds hollow, loud, or echoey. It's therefore about the subjective perception of sound.
Examples:
- You need to speak louder to remain understandable
- Conversations feel tiring
- Environmental sounds attract a lot of attention
- Concentrating and focusing is difficult
Sleep duration is the measurement.
Reverberation time is a technical measurement. This value indicates how many seconds a sound takes to decrease by 60 decibels after stopping.
Acoustic specialists express reverberation time in seconds.
A short reverberation time often results in:
- Better speech intelligibility
- More calm
- Higher concentration
A long reverberation time often causes:
- More echo
- Poor intelligibility
- A higher experienced sound pressure level
In brief: Echo is what you hear and reverberation time is what you measure.
Why Is Too Much Reverb a Problem?
Many people think that reverberation only sounds annoying. In practice, poor acoustics have much more significant consequences.
Reduced concentration: In a space with a lot of echo, sound remains present for longer. The brains have to work harder to distinguish important information from background noise. As a result, concentration decreases.
Poorer communication: When words overlap, miscommunication occurs more quickly. People more often ask for repetition and conversations take more energy.
More stress and fatigue: A noisy room constantly provides stimuli. This often leads to mental fatigue and irritation.
Less comfort: Even when people do not exactly know what is wrong, they often perceive a space with a lot of echo as restless and less pleasant.
How does echo occur?
Sound is usually caused by a combination of sound waves colliding against hard material and thereby reflecting. In short, there is a lack of sound-absorbing material.
Common causes include:
- Concrete ceilings
- Large glass partitions
- Hard floors
- Bare walls
- Open spaces
- High ceilings
- People and/or machines that produce noise
Modern buildings often contain a lot of glass, steel, and concrete. These materials suit a sleek design well but hardly absorb sound. As a result, the chance of reverberation increases significantly.
In which rooms does reverb often occur?
Offices: open office environments contain many conversations, phone calls, and foot traffic sounds. Without acoustic measures, disquiet quickly arises.
Meeting Rooms: good communication is central during meetings. Echoing makes conversations less clear and reduces the effectiveness of a discussion.
Schools: pupils and teachers benefit from clear speech intelligibility. A calm acoustic environment supports the learning process.
Horeca: guests want to relax, eat, and chat. Good acoustics provide greater comfort and a pleasant atmosphere.
Healthcare Facilities: silence plays an important role in recovery and wellbeing. Sound absorption contributes to a comfortable environment for visitors, staff, and patients.
Residences: Regular echo also occurs at home, especially in new-build houses with hard floors, smooth walls, and lots of glass.
How Do You Measure Reverberation Time?
A professional acoustic measurement provides insight into the reverberation time of a space.
During the measurement, our acoustic consultants analyse:
- The volume of the space
- The materials used
- The noise level
- The frequencies of the sound
The results show whether the acoustics meet the function of the space.
For example, a classroom requires a different reverberation time than a restaurant or production hall.
Conclusion: Addressing the problem begins with insight
Reverberation occurs when sound is reflected too often in a space. This affects concentration, communication, and comfort. Reverberation time is the technical measure that indicates how strong this effect is.
The difference is simple:
- Sound is what you hear.
- Reverberation time is what you measure.
With the right acoustic solutions, you create a space where people can work, learn, live or gather comfortably.
Want to know how to reduce noise in your space? The specialists at EASY Noise Control are happy to assist with suitable acoustic advice and a solution that delivers immediate results.
FAQ
What is reverberation?
Reverberation occurs when sound waves reflect off hard surfaces and repeatedly re-enter the space. This is also known as echo. You hear the sound lingering longer, which increases noise in the room and makes voices less clear. By reducing reverberation, the sound becomes quieter and voices are easier to understand.
How do you recognise reverberation, hollow sounds, and echoes in a space?
Reverberation, hollow sounds and echoes are recognisable by a sound that lingers after you've spoken. In a space with reverb, your voice sounds less sharp and the sound appears to "float" for a moment. With hollow sounds, you hear a dull, empty noise, especially when you walk, talk, or clap. An echo occurs when the same sound clearly bounces back from a hard wall or ceiling.
Spaces with many hard materials, such as concrete, glass or tiles, will exhibit these effects more quickly. You also often notice that conversations are harder to follow and that you become fatigued more quickly.
How can I reduce reverberation in a room?
Reverberation is most effectively reduced by providing hard, reflective surfaces with sound-absorbing materials. Think of acoustic wall panels, ceiling panels, or other solutions that absorb sound rather than reflect it. Which approach delivers the best results depends on various factors. The current and desired reverberation time are important starting points. Additionally, the size and shape of the space, the location of sound sources, the position of listeners, and the usage of the space all play a significant role. With an acoustic analysis, you gain insight into the situation and can precisely determine where and how much sound absorption is needed for a calm, comfortable, and clearly intelligible environment.
What is sound?
To understand what acoustics means, it is important that you first know what sound is. Sound is a vibration that travels through a medium, such as air, water or metal. You perceive sound with your hearing. Your ear is especially tuned to sound that travels through the air. How does sound occur? To produce sound, you need a source. This source causes the air to vibrate with enough energy. Through that vibration, the air pressure changes locally:
- Air particles compress together (higher pressure)
- Then they move apart again (lower pressure)
This alternation creates pressure waves. These waves travel through the air and reach your ear. That’s how you hear sound.
What is acoustics?
Acoustics are different for everyone. This is because everyone experiences sound differently. The characteristics of the sound in a space determine how you perceive that sound. Someone who is used to spaces with a lot of reverberation often finds a similar space pleasant and may describe the acoustics as good. Someone who is accustomed to spaces with little reverberation might find that same space uncomfortable and may describe the acoustics as poor. You might experience the acoustics as good, while someone else might find it less pleasant. In short: acoustics are your personal perception of sound in spaces and environments, and that perception varies from person to person.
What Is Sound Absorption?
Sound absorption means that a material absorbs sound waves instead of reflecting them back. An absorbing material removes the energy from the sound wave. As a result, echo and reverberation are reduced, and a space sounds quieter and clearer. Materials such as felt, wool, acoustic foams, and acoustic panels have an open structure. Sound waves penetrate and weaken within them. This causes the sound to return less loudly into the space. This has several advantages:
- Better speech intelligibility: conversations sound clearer and people need to speak less loudly.
- More concentration: there is less distraction from background noise, making it easier to maintain focus.
- Higher productivity: in quiet spaces, people work faster and make fewer mistakes.
- Less fatigue: a room with less echo feels calmer. Your brain has less effort to filter sound. This prevents listening fatigue.
In short: sound absorption provides more calm, clarity, and comfort in any space.
