Current RT60
RT60 describes the time for a room’s sound level to decay by 60 dB under stated conditions. This tool estimates it from room volume, surface area and an assumed average absorption.
Estimate reverberation
early in the design
Use the room dimensions, intended use and an assumed average absorption to obtain an indicative RT60 estimate and discuss the need for acoustic treatment.
What this estimate tells you.
Use the result to start an acoustic discussion and compare early design options. The calculation does not measure the room or establish final product quantities.
Room target
The selected room type provides a planning target for comparison. Review the appropriate project target with an acoustic specialist.
Treatment area
Additional equivalent absorption area is an acoustic quantity. It is not the physical face area of a panel or a final purchase quantity; product performance and mounting determine the treatment required.
Engineering fundamentals
Questions about Archiphonic
Key concepts in architectural acoustics, preliminary estimation formulas and the questions to address before design begins.
Preliminary RT60 estimateRT60 = 0.161 × V / AV — room volume, m³
A — equivalent sound absorption area, m²
A — equivalent sound absorption area, m²
01 · Sound physics
What happens to sound energy at a surface?
Incident energy is divided into reflected, absorbed and transmitted components:
1 = R + A + TArchiphonic increases the absorbed share: air movement through the fibrous structure creates friction, converting part of the acoustic energy into heat.
How are frequency and wavelength related?
c = f × λHere c is the speed of sound, f is frequency and λ is wavelength. At 20 °C, sound travels through air at approximately 343 m/s. The lower the frequency, the longer the wavelength and the more difficult it is to address with a thin porous material.
How do absorption, diffusion and sound insulation differ?
Absorption reduces reflected sound energy within a room. Diffusion redirects reflections. Sound insulation limits transmission between rooms and depends on the complete multilayer construction.
02 · Calculation and design
What is RT60 and how is it estimated?
RT60 is the time required for the sound level to decay by 60 dB after the source stops. Sabine’s formula is used for a preliminary estimate:
RT60 = 0.161 × V / AThe result is indicative. Room geometry, surface distribution, furniture and measured material coefficients must be reviewed during acoustic design.
How is the required absorption area estimated?
First define the target reverberation time, then estimate the required equivalent absorption area:
A = 0.161 × V / RT60Each surface contributes Sᵢ × αᵢ, and the total is the sum of these contributions:
A = Σ(Sᵢ × αᵢ)Why do material thickness and the air gap matter?
Thickness and mounting determine the effective frequency range. An air gap behind a porous absorber increases the sound path and can improve absorption at lower frequencies. Final performance must be confirmed against data for the specific product and installation.
Why can baffles outperform flat lining of the same plan area?
Several faces and edges of a freely suspended element remain exposed. A baffle interacts with sound arriving from different directions and helps control ceiling reflections without completely concealing building services.
Where should panels, baffles and screens be placed?
Placement follows early-reflection paths and room use: baffles in the ceiling zone, panels on reflective wall areas, and screens or acoustic furniture close to work and conversation zones.
03 · Ratings and measurement
What is the difference between α, αw and NRC?
α is the absorption coefficient at a specific frequency. αw is a single weighted value defined by ISO 11654. NRC is an average of several frequency-band coefficients. Products should only be compared using the same test method and mounting arrangement.
What do STI, NC and Rw describe?
STI describes speech intelligibility, NC describes background-noise level, and Rw describes the sound insulation of a building element. They address different requirements and are not interchangeable.
How does ISO 354 differ from ISO 3382?
ISO 354 is used to measure material sound absorption in a reverberation room. ISO 3382 covers measurements of reverberation time and other acoustic parameters in completed rooms.
How is the absorption coefficient measured in a laboratory?
Decay times in a reverberation room are compared before and after the specimen is installed. The reference relationship is:
α = (55.3 × V / c × S) × (1/T₁ − 1/T₂)V is chamber volume, c is the speed of sound, S is specimen area, and T₁ and T₂ are reverberation times without and with the specimen. The measurement is performed by an accredited laboratory.
Let’s shape
the sound
Tell us how the room is used, its approximate area and where reflected sound is a problem. We will discuss a suitable product family and the next assessment step.