The Science of How Rooms Sound
Every room has a voice. A cathedral wraps sound in seconds of echoing reverberation; a recording studio absorbs it almost instantly. Architectural acoustics — the science founded by Wallace Clement Sabine in 1898 — explains why. Sabine discovered that reverberation time depends on just two things: the volume of the room and how much sound its surfaces absorb. His equation, RT60 = 0.161V/A, remains the foundation of acoustic design today.
The Sabine Equation
RT60 measures how many seconds it takes for sound to drop by 60 decibels — roughly from conversational volume to silence. The formula is elegantly simple: multiply room volume (m³) by 0.161, then divide by total absorption (surface area × absorption coefficient). Hard surfaces like concrete (α ≈ 0.02) reflect almost all sound; soft materials like heavy curtains (α ≈ 0.55) absorb over half. The simulation lets you adjust materials and see RT60 change instantly.
Designing for Purpose
The ideal reverberation time depends entirely on what happens in the room. Speech intelligibility requires short RT60 — classrooms should aim for 0.6 to 1.0 seconds so that consonants don't blur into reverberant mush. Orchestral music needs longer decay — 1.8 to 2.2 seconds — to blend instruments and create warmth. The great concert halls of the world (Vienna Musikverein, Boston Symphony Hall) were designed to hit these targets precisely.
Beyond Sabine: Modern Acoustic Design
The Sabine equation assumes sound energy is evenly distributed — a simplification that fails in long, narrow rooms or spaces with uneven absorption. Modern acousticians use ray-tracing software to simulate thousands of sound reflections, predicting exactly how a room will sound before it is built. Yet the fundamentals remain: volume, surface area, and absorption. This simulator gives you the tools Sabine used to revolutionize how we design spaces for the human ear.