Acoustics
Hall acoustics
The acoustics gate separates isolation from treatment, and reads RT60 with frequency, volume, and use instead of one number pasted on every hall.
A hall’s acoustics are three different questions: whether sound stays in the room, how it behaves inside, and whether speech is understood. Folding them into one line item produces a specification that cannot be measured.
Definition
This gate gathers sound isolation, internal treatment, and reverberation time. Isolation deals with energy that crosses the wall, the door, and the duct. Treatment changes absorption and diffusion inside the same volume. RT60 describes how fast energy dies, and it is a function of frequency, not a decor figure.
The sound system comes after the room is described. A clearer loudspeaker does not close a door gap, and it does not shorten a long decay into speech intelligibility. STI, from IEC 60268-16, is the question when speech must be understood, not when the hall only needs to “feel quiet”.
Common mistakes
One RT60 for the whole project — Writing one second for every space deletes the difference between a lecture, a sports hall, and a music room.
Foam on the wall instead of the door and the duct — Internal treatment does not repair a flanking path. Isolation fails at the opening, not at the wall colour.
Copying a coefficient from a catalogue — An α without a frequency, a mounting, and an ISO 354 report is not a calculation input. This gate does not supply that coefficient.
When needed
- Before the form is frozen — While volume, openings, the HVAC path, and surface build-ups can still change. After that, treatment becomes a patch.
- When the complaint is specific — Echo, hearing the hall in the corridor, or speech that stays unclear when the gain is raised. Each complaint points at a different question.
- Before buying the sound system — So the budget is not spent on a Line Array in a room whose clarity is still set by RT60 and the noise floor.
Published now
- Sound isolation — The gap between a laboratory Rw or STC and what reaches the next room after flanking, doors, and HVAC.
- Acoustic treatment — Absorption versus diffusion, and why a thin porous panel is weak at low frequency unless it is thicker or spaced off the surface.
- RT60 — Reading the time with frequency band, volume, and use, and the limit of Sabine when absorption is high.
- What the gate does not decide — No product absorption coefficient, no field isolation result, and no RT60 target imposed on every hall type.
Questions
Are isolation and treatment one service?
No. Isolation stops transmission. Treatment changes behaviour inside the room. A hall may need one or both, and the specification says which.
Does a short RT60 mean clear speech?
Not by itself. Noise lowers STI even when the decay is short. IEC 60268-16 describes the speech index. RT60 does not replace it.
Do we start with loudspeakers or with the room?
With the room: volume, isolation, decay, and HVAC noise. The sound system is designed on that result, not instead of it.
Is the Rw on the wall what I will hear?
No. Rw and STC are laboratory numbers. The site adds flanking, doors, and penetrations. Do not carry the figure across as a field result.
Where are the details?
The isolation, treatment, and RT60 pages under this gate, then the measurement standard itself. The page does not replace the standard.