What is reverberation and why it turns a venue into a sound trap
Have you ever noticed that in certain bars it is impossible to hear what the person sitting opposite you is saying? That is reverberation — and it can be measured with scientific precision.
How reverberation turns a venue into a noise chamber
When someone speaks in a room, the sound does not travel only towards the listener: it bounces off the walls, ceiling, floor and windows. Every bounce adds a delayed copy of the original sound. This effect is called reverberation.
In spaces with many hard surfaces — typical of modern bars and restaurants with concrete floors, exposed brick walls and high ceilings — reverberation can last 2–3 seconds. This means every sound continues to fill the room for that entire time, overlapping with the next sound. Speech becomes unintelligible, people raise their voices and the overall sound level rises exponentially.
This mechanism is known as the cocktail effect: every pair of people raises their voices to be heard, forcing those nearby to do the same. In a full venue, levels of 85–100 dB are easily reached even without any music.
RT60: the parameter that measures reverberation
RT60 (Reverb Time) is the fundamental parameter of architectural acoustics. Defined by the ISO 3382 standard, it measures the time — in seconds — required for the sound level to fall by 60 dB after the sound source stops.
In practice: once you stop speaking, how long does your voice take to fade from the room?
Sources: ISO 3382; UNI 11532; Sabine, Wallace C. (1900)
What determines the reverberation of a venue
The physicist Wallace Clement Sabine demonstrated in the late nineteenth century that reverberation time depends on only two factors: the volume of the room and the absorption capacity of the materials within it.
📐 Room volume
The larger the room, the more space sound has to propagate. A venue with 4–5 metre ceilings will naturally have more reverberation than one with low ceilings, all other materials being equal.
🧱 Surface materials
Concrete, glass, ceramics and metal reflect almost all sound. Carpet, curtains, acoustic panels and upholstered seating absorb it, reducing reverberation.
👥 Occupancy
Human bodies and clothing absorb sound. A venue at half capacity behaves acoustically very differently from the same venue when full. FANA surveys account for real-world usage conditions.
Acoustic absorption coefficients — common materials
The coefficient α ranges from 0 (total reflection) to 1 (total absorption). Values at 500 Hz — the central frequency of human speech.
| Material | Coefficient α (500 Hz) | Effect on reverberation |
|---|---|---|
| Glass / windows | 0.03 | 🔴 Highly reflective |
| Concrete / plastered brick | 0.03–0.05 | 🔴 Highly reflective |
| Wood (parquet) | 0.05–0.10 | 🟡 Moderately reflective |
| Upholstered seating (occupied) | 0.55–0.75 | 🟢 Good absorption |
| Carpet / rugs | 0.30–0.50 | 🟢 Good absorption |
| Certified acoustic panels | 0.80–1.00+ | 🟢 Excellent absorption |
| Heavy curtains | 0.35–0.55 | 🟢 Good absorption |
How to correct the reverberation of a venue
Reverberation is correctable in any venue, regardless of the existing architecture. A full refurbishment is not always required: often simple, minimally invasive measures are sufficient.
The FANA acoustic adjustment process involves:
- Instrumental acoustic survey of the venue (RT60 measurement by frequency band)
- Calculation of the absorption deficit needed to reach the target class
- Technical proposal specifying material types and positioning
- Choice of contractor (the venue’s own or one suggested by FANA)
- Final verification and issue of certification