The ideal RT60 is the reverberation time that supports a room’s main purpose without making speech unclear or music unnaturally dry. RT60 is measured in seconds and describes how long a sound takes to decay by 60 dB after the source stops.
There is no single ideal value for every room. The right target depends on room volume, frequency, audience, sound source and whether the space is used mainly for speech, music, recording or sound reinforcement.
What RT60 tells you
RT60 describes the decay of a room’s sound field, not the loudness of the room and not the quality of a reverb plugin. A long decay generally creates more spaciousness, while a short decay usually improves definition and speech intelligibility.
You can estimate a room’s reverberation time with the RT60 calculator or review the underlying methods in the RT60 formula guide.
RT60 and perceived room character
- A short RT60 can sound controlled, dry and precise.
- A moderate RT60 can provide natural warmth and useful support.
- A long RT60 can sound spacious, but may blur words, transients and fast musical passages.
These descriptions are listening cues, not a replacement for measurement. A room can also have uneven decay at different frequencies.
Common RT60 starting ranges
The ranges below are practical starting points rather than universal standards. The final target should be adjusted for room size, frequency and the actual use of the space.
| Main use | Common starting RT60 range | Main priority |
|---|---|---|
| Speech, classroom or meeting room | About 0.4–0.8 seconds | Clear words and low overlap |
| Small rehearsal or recording room | About 0.4–0.8 seconds | Control with enough liveliness |
| Studio control room | About 0.2–0.5 seconds | Accurate monitoring and detail |
| Small music room | About 0.8–1.2 seconds | Natural support without excessive blur |
| Larger music or performance space | About 1.2–2.0 seconds or more | Blend, fullness and musical sustain |
These values are not design specifications for every project. A qualified acoustician, measurement standard and the room’s intended use should guide final decisions for critical spaces.
How to choose an ideal RT60
Start with the room’s primary use
Choose the main task first. A lecture room needs speech clarity, while a chamber-music room may benefit from more sustained sound. If a room has several uses, select a practical compromise or use variable acoustic treatment.
Consider room volume
Larger rooms often need a longer decay to feel supported, but volume alone does not determine the target. Shape, absorption, seating, occupancy and surface distribution also affect the result.
Set targets by frequency
Do not judge a room from one broadband RT60 number only. Bass, midrange and high-frequency decay can behave differently. A room that has an acceptable average may still sound boomy if low-frequency decay is much longer than the midrange.
Account for occupancy and furniture
People, seats, curtains and other porous materials absorb sound. A room can therefore have a different RT60 when empty than when occupied. Decide whether the target applies to an empty, furnished or normally occupied condition.
Ideal RT60 for different spaces
Speech rooms
Speech spaces usually need a relatively short and even decay. Excess reverberation allows one syllable to overlap the next, reducing intelligibility. Prioritize control in the midrange and high frequencies where consonants carry important information.
Recording and mixing rooms
Recording spaces often use shorter, controlled decay so microphones capture fewer unwanted reflections. A mixing room also needs a predictable response so balance decisions are not dominated by the room.
For a practical production context, compare this target with the DAW reverb settings guide and mixing reverb guide. Those pages address artificial reverb; this page addresses the acoustic decay of a physical or simulated space.
Music and performance rooms
Music rooms may need more reverberation than speech rooms because sustained decay can add blend and fullness. The appropriate value depends on the ensemble, repertoire, room size and whether amplified sound is used.
Home studios and practice rooms
Small rooms often become problematic when low-frequency decay is long but mid and high frequencies are heavily absorbed. Treat the room for a balanced decay rather than simply adding more high-frequency absorption.
How to reduce or increase RT60
To reduce a long RT60
Use broadband absorption, soft furnishings and correctly placed acoustic treatment. Focus on the frequency range where decay is excessive, and avoid treating only the highest frequencies if the room still has a low-frequency problem.
To increase a very short RT60
Reduce excessive absorption or add suitable reflective or diffusive surfaces. The goal is controlled reflection, not random echo or flutter echo.
To keep the decay balanced
Use absorption with known, frequency-dependent performance. Review the absorption coefficients guide before estimating how a material will affect the room.
RT60 measurement and calculation limits
Calculated RT60 is an estimate based on assumptions about volume, surface area and absorption. Real rooms can differ because of non-diffuse sound fields, uneven material placement, room geometry, furniture, leakage and frequency-dependent absorption.
For a real room, measure decay from multiple positions and inspect separate frequency bands when possible. Treat a calculator result as a planning estimate, not a guarantee of the finished acoustic response.
Frequently asked questions
What is a good RT60 for speech?
A relatively short, even decay is usually preferred. About 0.4–0.8 seconds is a practical starting range for many speech rooms, but the correct target depends on room size, frequency and the required intelligibility.
Is a longer RT60 always better for music?
No. Longer decay can add blend and warmth, but too much reverberation can reduce definition and mask fast passages. The ideal target depends on the music and room.
Should RT60 be the same at every frequency?
Not necessarily, but large differences between bands can create audible problems. Inspect the frequency-dependent decay instead of relying only on one average number.
Does room size determine ideal RT60?
Room size influences the target, but it is not the only factor. Use, occupancy, materials, geometry and sound source also matter.
Can I calculate ideal RT60 with a formula?
You can estimate reverberation time with the Sabine formula or Eyring formula. These formulas estimate decay from room and absorption data; they do not decide the best target for the room’s purpose.
Noah Bennett is an audio engineering writer and acoustics specialist at Reverb Calculator. He focuses on reverb time calculation, room acoustics, studio sound design, and music production tools for producers, audio engineers, musicians, and home studio creators.