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Room acoustics calculator: reverberation, room modes and isolation
Type your room's dimensions and what is on the floor, the walls and the ceiling. It tells you how long it rings in each frequency band, which notes the room resonates at, how many square metres of treatment you are short, and at what frequency a double wall resonates.
The coefficients come from 245 materials with real manufacturer data sheets, 77 of them sold in the United States, each one citing its source. No generic table averages with nobody behind them.
Your room
Inside dimensions, wall to wallLa cuenta toma la sala vacía: muebles, ropa, cortinas y las personas que estén dentro bajan el resultado real, sobre todo en medios y agudos. Si tienes cortinas o alfombra, modélalas en el piso o en las paredes para acercarte. 245 materiales con curva de absorción de ficha técnica, la mayoría conseguibles en Latinoamérica. Este se ensayó según ASTM C423 Montaje A.
Reverberation time
35.7 m³ · 67 m² de superficieRT60 at 500 Hz
1.63 s
Target
0.20–0.30 s
Bands on target
0 de 6
La sala es reflectante (α media ≤ 0,20); Sabine y Eyring casi coinciden y se usa Sabine. Objetivo según EBU Tech 3276 — Tm = 0,25·(V/100)^(1/3).
La EBU pediría 0.18 s, pero está pensada para salas de escucha grandes: en 36 m3 ese número exige forrar casi media sala y deja un cuarto muerto. Se usa 0.25 s, que es lo que se busca en la práctica en salas de control pequeñas.
En 125 Hz se admiten hasta 0,3 s por encima del objetivo: ninguna norma exige el mismo tiempo en graves que en medios, porque bajar los graves cuesta espesor, no metros cuadrados.
How much treatment is missing
Sized at 500 Hz, at the top of the rangeFaltan 14.6 m² de Black Theater 50.8 mm 48 kg/m3 (Isover), que son unos 21 paneles de 60 × 120 cm.
La cuenta descuenta lo que ya absorbía la pared que queda tapada: sumar la absorción del panel sin restar la de la superficie es la forma habitual de calcular de más. Además se dimensiona contra el límite alto del rango y no contra el centro, porque apuntar al centro pide casi el doble de material y deja la sala muerta: siempre es más fácil colgar un panel más que devolverle vida a un cuarto sobre-tratado.
| Band | Current absorption | Needed | m² faltantes |
|---|---|---|---|
| 125 Hz | 1.0 | 9.6 | 66.4 |
| 250 Hz | 1.8 | 14.4 | 19.0 |
| 500 Hz | 3.5 | 19.2 | 14.6 |
| 1 kHz | 8.8 | 19.2 | 9.7 |
| 2 kHz | 11.0 | 19.2 | 8.3 |
| 4 kHz | 11.8 | 16.4 | 4.9 |
Room modes
Transition at 357 HzPor debajo de 357 Hz la sala no tiene un campo sonoro parejo: manda cada modo por separado, y ahí es donde el bajo se oye distinto según dónde te sientes. Por encima, el promedio del RT60 ya describe bien lo que pasa.
Las proporciones caen dentro de la zona recomendada de Bolt y reparten bien los modos graves.
Proporciones 1.68 : 1.36 : 1 (largo : ancho : alto).
Double wall: what frequency does it resonate at?
Mass-spring-massTwo leaves separated by air make a spring. Below its resonance frequency a double wall isolates worst than a single layer would. If that frequency falls inside the music, the wall gives back exactly what you were trying to contain.
60 Hz
f0 en 60 Hz: aceptable para voz y para música sin subgraves fuertes, pero un bombo de reggaetón la va a encontrar.
Con la cámara vacía subiría a 84 Hz: rellenarla de lana no es opcional, es lo que baja la resonancia.
Hasta aquí llega la cuenta rápida
Esta calculadora supone que la absorción está bien repartida y no mira dónde te sientas, dónde están los monitores ni por dónde se cuela el ruido del vecino. Eso ya es un diagnóstico, y es lo que hace el reporte.
How this is calculated, no mystery
Reverberation time is how long sound takes to drop 60 dB after the source stops. Sabine's formula estimates it as RT60 = 0.161 · V / A, where V is the volume in cubic metres and A is total absorption: every surface multiplied by its coefficient in that frequency band. Because the coefficient changes with frequency, so does the result — which is why you get six numbers here and not one.
Sabine assumes sound is spread evenly through the room. In a small, well-treated room that stops being true and the formula returns a longer time than reality. When the average coefficient goes above 0.20, this calculator switches to Eyring, which corrects that bias. It tells you which one it used and why, instead of handing you a number and staying quiet.
In the bass neither formula describes what actually happens, because down there geometry rules: the modes. The boundary is the Schroeder frequency, f = 2000·√(RT/V). In a typical studio room it lands between 100 and 200 Hz, and below that an average means nothing.
What this calculator cannot know
It is for sizing the problem and understanding it, not for signing off a build. It assumes absorption is spread evenly, and it almost never is: putting all the material on one wall gives the same number in the formula and a very different result in your ears. It also does not know where you sit or where the monitors are, which is what decides which modes hit you and where the early reflections land.
And it says nothing about noise getting in or out: that is isolation, a different problem solved with mass, airtightness and decoupling, not with panels. The double wall block above is only the first question of that other problem.
Frequently asked questions
Will acoustic panels stop my neighbour hearing me?
No, and this is the most expensive misunderstanding in the whole field. Panels change how the room sounds on the inside — that is treatment. Keeping sound from getting in or out is isolation, and it is solved with mass, airtightness and decoupling, not with foam. A room covered in panels can still be perfectly audible next door.
What RT60 should a home studio have?
For a small control or mix room, roughly 0.2 to 0.3 seconds, and — more important than the number — reasonably even across bands. A room that measures 0.25 s at 1 kHz and 0.7 s at 125 Hz is not a 0.25 s room: it is a room with a bass problem that a single average number hides.
How many acoustic panels do I need?
It depends on the volume of the room, what the surfaces already absorb and what you use the room for — which is what this calculator works out. Be wary of rules of thumb like 'cover 40% of the walls': the same percentage in two rooms with different floors gives completely different results.
Is NRC enough to choose a material?
No. NRC averages the 250, 500, 1000 and 2000 Hz bands and ignores 125 Hz entirely, which is precisely where a small room's problems live. Two materials with the same NRC can behave very differently in the bass. Look at the full octave-band curve, and at the mounting it was tested with.
Does the mounting really change the numbers that much?
Yes. The same panel flat against the wall and spaced 100 mm off it are two different curves, and the difference shows up mostly in the low mids, where it matters. A data sheet that does not state the mounting is giving you half the information.
Want someone to look at your room?
This sizes the problem. A remote design turns it into a plan: scale drawing, every panel specified, materials list and build order, delivered in four business days.
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