How Much Soundproofing Does a Shared Office Booth Actually Need?
Most shared office phone booths need roughly 25 to 32 dB of speech reduction to keep private calls confidential. Here is how acoustic ratings work and what to look for.
In this article
- Key takeaways
- How much noise does a standard phone call generate?
- What acoustic rating should you look for?
- Where do phone booths lose their soundproofing?
- What is the honest trade-off with high soundproofing?
- Can you build your own booth or should you buy prefabricated?
- How many phone booths do you actually need?
A coworking phone booth needs between 25 and 32 decibels of total speech reduction to protect member privacy. You do not need absolute silence, because normal ambient chatter in an open office does the rest of the masking work for you.
If your space runs at an average hum of 45 to 50 dB, knocking a 60 dB speaking voice down by 30 dB makes private conversation completely unintelligible to someone sitting four feet away.
Key takeaways
- Aim for an acoustic reduction level between 25 dB and 32 dB for routine calls and video meetings.
- Acoustic rating standard ISO 23351-1 evaluates speech level reduction specifically for office phone booths and pods.
- Complete soundproofing is unnecessary and counterproductive, as sound traps stifle passive airflow.
- Glass thickness, door seals, and ventilation baffles determine performance far more than outer wall panels.
How much noise does a standard phone call generate?
A normal speaking voice sits between 60 and 65 dB at a distance of one meter. A raised voice or an animated pitch during a presentation easily hits 70 to 75 dB.
In a coworking space, your goal is not to make the booth user disappear from reality. The goal is speech privacy, often called acoustic comfort. Speech privacy occurs when surrounding coworkers can hear a faint murmur, but they cannot distinguish individual words or sentences. When words become unintelligible, the brain stops trying to process them, and distraction drops to near zero.
What acoustic rating should you look for?
Look for products tested against ISO 23351-1, which measures speech level reduction ($D_{S,A}$) for furniture ensembles and phone pods. Under this testing standard, units fall into distinct acoustic classes based on how well they reduce vocal frequencies.
| ISO 23351-1 Class | Speech Level Reduction ($D_{S,A}$) | Privacy Level in a Typical Office |
|---|---|---|
| Class A | 30 dB or greater | High speech privacy; safe for confidential and financial calls |
| Class B | 27 dB to less than 30 dB | Standard privacy; normal voices are muffled and hard to understand |
| Class C | 24 dB to less than 27 dB | Mild privacy; suitable for quiet calls if ambient noise is above 45 dB |
| Below Class C | Under 24 dB | Poor isolation; adjacent desks will clearly hear phone conversations |
Class A or Class B ratings are what you should look for in a professional workspace. Anything below 24 dB will lead to complaints from both the caller and the person working outside the glass.
Where do phone booths lose their soundproofing?
Sound behaves like water: it escapes through the path of least resistance. You can build panels with dense structural materials, but if you cut corners on the assembly joints, sound leaks out immediately.
First, inspect the door seals. Magnetic seals or drop-down mechanical bottom sweeps are essential. A half-inch gap under a glass door can leak enough acoustic energy to ruin a 30 dB wall build.
Second, check the glass specification. Single-pane standard glass resonates and carries high frequencies directly into the room. Reliable office booths use laminated acoustic glass, typically between 8 mm and 10 mm thick, containing a transparent sound-dampening interlayer.
Third, look at the ventilation channels. A person generates heat and carbon dioxide rapidly inside a 10-to-15-square-foot enclosure. Booths need electric intake and exhaust fans moving air at roughly 30 to 40 cubic feet per minute. Because air channels create direct holes through the ceiling or walls, the manufacturer must use internal acoustic baffles, which are lined labyrinths that force sound waves to bounce off absorbent materials before reaching the outside room.
What is the honest trade-off with high soundproofing?
The honest drawback of aggressive soundproofing is thermal discomfort.
The more acoustic material and baffles you layer over the ventilation paths, the harder fans must work to pull fresh air into the cabin. Highly isolated booths get stuffy fast during 45-minute sales calls. If the manufacturer increases fan speed to fight the heat, fan motor noise creeps into the user microphone, destroying call clarity. You are always balancing acoustic containment against fresh air and internal noise.
Can you build your own booth or should you buy prefabricated?
Small operators often think building a phone booth out of regular stud drywall and acoustic rockwool will save them money. Drywall booths soundproof reasonably well if built with double-layer gypsum and green glue, but they create two major operational problems.
Permanent drywall structures count as architectural alterations. In most commercial leases, you cannot take them with you when you move, and local building codes often require you to extend commercial sprinkler systems and HVAC supply ducts into the ceiling of any permanent room.
Prefabricated pods avoid this headache. They are classified as commercial furniture, draw power from an ordinary 110V or 220V wall plug, roll on casters or flat-pack during an office move, and sit beneath existing overhead fire suppression without requiring dedicated pipework. If you only operate a single room, a DIY booth can work, but a commercial pod saves thousands in permitting delays.
How many phone booths do you actually need?
For hot-desk open plans, place one single-person booth for every 10 to 15 desks. If your space caters heavily to remote software salespeople, account managers, or legal consultants, tighten that ratio down to one booth for every 7 to 8 desks.
If members consistently wait in line to take unexpected calls, they will take those calls straight from their open desks, defeating the entire purpose of having soundproofing in the building. Keep booths situated within a quick 10-second walk of your busiest desk banks, set clear 30-minute usage guidelines, and you will maintain a calm, functional workspace.
