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The Resonics Guide to Reverberation Time
Reverberation time (RT) is one of the most important concepts in interior acoustics — and for a good reason.
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Guide
Reverberation time plays a key role in diagnosing and solving noise issues in almost any type of space.
But what is Reverberation Time (RT)?
Simply put, RT measures how long it takes for sound to drop by 60 decibels after the original sound source has stopped.
Why is RT important?
Understanding a room’s RT gives us a clear indication of how sound behaves within that space and how much it lingers.
This is crucial when identifying the severity of a noise problem and selecting the right acoustic treatments. Different rooms serve different purposes and each one will require a tailored level of sound absorption to achieve optimal acoustic comfort.
Why is RT the main metric we focus on?
Rooms with long RTs typically suffer from excessive echo and background noise. In these environments, sound waves reflect off hard surfaces, travelling and overlapping, rather than being absorbed. This results in poor speech intelligibility and low acoustic comfort, making it harder to concentrate, communicate or relax.
Whether it’s a restaurant where conversations become muddled, a classroom where students struggle to hear their teacher or an office filled with distracting echoes, high RT is often the root cause.
Despite the importance of reverberation time, there is still limited guidance on acceptable levels across different room types.
After years of working in a range of interior spaces, from open-plan offices to auditoriums, we’ve developed our own set of recommended RT ranges. These act as a reliable baseline for achieving acoustic comfort and clarity, ensuring each space is treated appropriately for its intended use.
| Room Type | Suggested RT |
| Open Plan Office | <1.0 second |
| Enclosed Office | <0.6 seconds |
| Meeting Room | 0.6 – 0.8 seconds |
| AV/VC Room | <0.5 seconds |
| Primary/Nursery Classroom | <0.6 seconds |
| Secondary School | <0.8 seconds |
| Lecture Hall | <1.0 second |
| Theatre/Auditorium | 1.5 – 2.0 seconds |
| Assembly Hall | 0.8 – 1.2 seconds |
| School Corridor/Stairwell | <1.5 seconds |
| Dining Room/Canteen | <1.0 second |
| Restaurant | <1.0 second |
| Church/Village Hall | <1.5 seconds |
| Library | <1.0 second |
| Swimming Pool | <2.0 seconds |
| Call Centre | <0.8 seconds |
| Cinema | 0.8 – 1.2 seconds |
| Sports Hall | <1.5 seconds |