How to Improve Conference Room Speech Clarity with Acoustic Panels
Glass on two sides, a hard ceiling, a large table, and a whiteboard. That is the standard modern meeting room, and acoustically it is close to the worst arrangement you could design on purpose.
Every surface reflects. The parallel glass walls bounce sound between themselves. The table throws speech straight up into the ceiling, which sends it back down. Someone at the far end asks for a point to be repeated, the remote participants hear a hollow room, and the meeting runs ten minutes longer than it needed to.
None of that requires much absorption to fix. Conference rooms are small, which means a modest area of well-placed panels changes the room completely. The money is wasted only when it goes on the wrong surfaces.
This article covers which surfaces matter and why. PRANCE manufactures acoustic perforated board systems used in commercial office interiors.
What Speech Clarity Depends On
Two measurable things, and they are not the same.
Reverberation time, RT60, measures decay. In a small room it governs whether speech syllables overlap each other.
Speech Transmission Index, STI, measures how much of a spoken message survives the room. Values above approximately 0.60 are generally considered good, and above 0.75 excellent. Below roughly 0.45 listeners start working to follow the conversation, which is exhausting over an hour.
A room can be quiet and still unintelligible. Reverberation smears consonants into each other, and consonants carry most of the meaning in speech, which is why people in reverberant rooms hear that something was said without catching what it was.
Targets for Meeting Rooms
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Small meeting room, up to 50 cubic meters: RT60 approximately 0.4 to 0.5 seconds
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Medium conference room, 50 to 150 cubic meters: approximately 0.5 to 0.6 seconds
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Large boardroom, above 150 cubic meters: approximately 0.6 to 0.8 seconds
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Video conference room, any size: toward the lower end of its range
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Untreated glass-and-plasterboard room: commonly 0.8 to 1.2 seconds
Typical ranges. Volume drives the figure more than seat count does.
Video rooms want tighter targets than in-person rooms because a microphone picks up the reverberant field along with the direct voice, and it cannot distinguish between them the way a human listener partly can.
Conference Room Acoustic Panels: Where They Go
Three locations carry almost all the benefit in a room this size.
1. The Ceiling
Same logic as every other room type. Largest uninterrupted surface, faces every reflection path, out of reach of people and furniture.
In a conference room the ceiling also sits directly above the table, which is the main reflecting surface in the room. Sound goes table to ceiling to listener as a strong early reflection, and absorbing that path does more for clarity than any wall panel.
An absorptive ceiling across the full room area, delivering NRC 0.70 or above, resolves most small-room problems before a single wall panel is considered. The mechanism behind an absorptive ceiling explains why the backing rather than the perforation does that work.
2. First Reflection Points on the Walls
These are specific locations rather than general wall coverage, and finding them is straightforward.
A first reflection point is where sound from a speaker bounces off a wall once before reaching a listener. In a rectangular room with a central table, those points sit on the side walls roughly level with the middle third of the table, at seated head height.
Treating a panel of absorber at each of those points removes the strongest early reflections. In a room with one glazed side wall, treating the opposite solid wall becomes more important, since the glass cannot be treated and keeps sending energy across.
3. The Wall Behind the Display
Modern meeting rooms put a screen at one end and the camera with it. The wall behind and around that screen reflects sound from everyone in the room straight back toward the microphone.
Treating the display wall improves what remote participants hear more than almost anything else. It is also usually the easiest wall to treat, since nobody sits against it and the screen already breaks up the surface.
Acoustic Panels for Video Conference Rooms
Hybrid meetings changed the requirement, and plenty of rooms built before 2020 were never designed for it.
A human listener in the room performs a remarkable amount of unconscious processing, separating a voice from its reflections. A microphone does not. It captures direct sound and reverberant energy together, and whatever it captures is what remote participants receive.
That has three consequences for treatment.
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Tighter RT60 targets, toward 0.4 to 0.5 seconds even in medium rooms
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Priority on the display wall, since it reflects toward the camera position
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Attention to the table surface, which reflects upward into ceiling microphones
Where ceiling microphone arrays are used, the ceiling treatment around them matters more. An array mounted in a reflective ceiling plane picks up reflections from that plane before anything else.
Parallel hard surfaces also produce flutter echo, which a microphone renders as a metallic ring on consonants. Treating one surface of each parallel pair removes it.
Speech Privacy Is a Different Problem
Worth separating clearly, because the two requirements pull in opposite directions and get confused constantly.
Absorption inside the room improves clarity for the people in it. It does nothing to stop a confidential conversation being heard in the corridor or the adjacent office.
That is a containment question, measured as Ceiling Attenuation Class, tested to ASTM E1414, with values of CAC 30 to 40 typical for ceiling systems. It depends on panel mass, backing, and edge sealing, and crucially on whether sound can travel over the partition through the plenum.
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For clarity inside the room: maximize NRC, typically 0.70 to 0.90
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For privacy from outside: run the partition to the structural slab, seal penetrations, and specify a higher CAC ceiling
A highly absorptive perforated ceiling is a poor acoustic barrier, since the holes that admit sound to the absorber also admit it to the plenum. Where a boardroom genuinely needs confidentiality, taking the partition to the slab is far more reliable than asking the ceiling to do both jobs.
Coverage and Panel Performance
Small rooms need less absorption than people assume, and the area required falls as panel performance rises.
| Room volume | Typical RT60 target | Indicative treated area |
|---|---|---|
| Up to 50 m³, 4 to 6 people | 0.4 to 0.5 seconds | Full ceiling, no wall panels often sufficient |
| 50 to 150 m³, 8 to 14 people | 0.5 to 0.6 seconds | Full ceiling plus first reflection points |
| Above 150 m³, boardroom | 0.6 to 0.8 seconds | Full ceiling, side walls, display wall |
| Video-enabled, any size | Lower end of range | Full ceiling plus display wall as priority |
Indicative only. An acoustician should calculate against actual volume, surface materials, and furnishing.
Panel performance matters as much as area:
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Solid metal or plasterboard: NRC around 0.05
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Perforated metal, 16% to 22% open area with fleece: NRC 0.70 to 0.90
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Micro-perforated metal: NRC 0.60 to 0.85, visually solid at normal distance
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Perforated with mineral wool at greater plenum depth: NRC up to 0.95 typical
Micro-perforation suits boardrooms and client-facing rooms specifically, because it delivers real absorption while the ceiling reads as a clean plane from the table.
Material Choice in an Office Environment
Conference rooms are gentler than restaurants or gyms, which widens the options.
Fabric-wrapped absorbers work well on walls, come in a wide range of finishes, and are common in office and boardroom fitouts. They mark over time, particularly at chair-back height, and cannot be cleaned easily.
Perforated metal handles the ceiling plane, delivers comparable absorption, cleans, and is non-combustible, typically achieving Class A under ASTM E84 and A1 or A2-s1,d0 under EN 13501-1. On a ceiling the durability argument is less about impact and more about plenum access, since meeting rooms carry lighting, sensors, and AV cabling that get adjusted regularly.
A practical split puts metal on the ceiling where access and fire classification matter, and allows fabric on wall panels where appearance leads and contact is limited.
What Usually Goes Wrong？
Treating a small room like a large one. A 40 cubic meter room needs very little absorption, and over-treating makes it feel oppressive and unnaturally dead.
Covering walls while leaving the ceiling hard. The table-to-ceiling reflection path is the strongest one in the room.
Confusing clarity with privacy. Absorption inside the room does nothing for containment, and a highly perforated ceiling actively reduces it.
Ignoring the display wall in a video room. It reflects toward the camera and microphone position.
Specifying acoustic without a number. A ceiling described as acoustic can deliver NRC 0.05 and comply with what was written.
Getting a Meeting Room Right
Treat the ceiling across the full area, find the first reflection points on the side walls, and deal with the wall behind the display if the room carries a camera. Keep the target modest, because a small room over-treated feels worse than one slightly under-treated.
Then stop. Meeting rooms are the one application in this set where restraint produces a better result, unlike dining rooms that defeat conversation, tiered spaces with a performer and an audience, or sports halls and the reverberation they generate.
PRANCE manufactures perforated and micro-perforated aluminum ceiling and wall panels with custom open area, acoustic backing, and tested NRC and CAC data for the configuration supplied. Send your room dimensions and whether the space is video-enabled and request panel options.
Frequently Asked Questions
1. How many acoustic panels does a conference room need?
Fewer than most people expect. A small room of up to 50 cubic meters is often resolved by an absorptive ceiling alone at NRC 0.70 or above. Larger rooms add first reflection points on the side walls and the wall behind the display.
2. Do acoustic panels help with video call audio quality?
Yes, substantially. A microphone captures reverberant energy along with the direct voice and cannot separate them the way a listener partly can, so reducing reverberation directly improves what remote participants hear. Video rooms should target the lower end of the RT60 range for their size.
3. Will acoustic panels stop people outside hearing the meeting?
No. Absorption improves clarity inside the room and does nothing for containment. Speech privacy depends on partition construction, sealing, and plenum path, so the partition should run to the structural slab rather than stopping at the ceiling.
4. Should panels go on the ceiling or the walls in a meeting room?
The ceiling first. It is the largest uninterrupted surface and it intercepts the strong table-to-ceiling reflection path that carries most of the problem. Wall panels come second and should target first reflection points rather than covering area generally.
5. What reverberation time should a conference room have?
Approximately 0.4 to 0.5 seconds for small rooms, 0.5 to 0.6 for medium, and 0.6 to 0.8 for large boardrooms, with video-enabled rooms at the lower end of their range. Untreated glass-and-plasterboard rooms commonly measure 0.8 to 1.2 seconds.