Sound Masking

Definition

Sound Masking

Adding sound to make a space feel quieter, which is less contradictory than it first appears.

Sound masking adds a low-level, engineered background sound to a space so that speech from further away becomes unintelligible. It does not reduce noise — it raises the noise floor so that conversations blend into the background sooner. It is distinct from soundproofing, which blocks sound, and from acoustic absorption, which reduces reflections. Typical systems run at 42 to 48 dBA, shaped to match the frequency profile of human speech.

How it works

Raising the noise floor

Speech becomes unintelligible when the background level is close enough to it. Sound masking exploits this by adding a continuous, engineered sound — usually through ceiling speakers — that sits just below conscious attention but high enough to obscure conversation from a few desks away.

The sound is shaped to match the frequency profile of speech, which is what makes it effective at low levels. It is not white noise, though it is often described that way. White noise has equal energy at all frequencies and is noticeably hissy; masking sound is filtered to cover the speech range specifically.

Well-tuned masking is not consciously noticeable. People typically only detect it when it is switched off, at which point the room feels oddly exposed.

What it does and does not do

Boundaries

It does reduce distraction from conversations two or three desks away, increase the effective distance at which speech becomes unintelligible, and improve subjective concentration in open-plan floors.

It does not make a space quieter. Measured decibel levels go up, not down. It does not stop someone at the next desk being heard, and it does not deliver confidentiality — a masked open-plan floor is still a place where private conversations should not happen.

It is also not a substitute for enclosure. If the requirement is that a conversation cannot be overheard at all, masking is the wrong tool and no amount of tuning will make it the right one.

Where it fits

Alongside, not instead of

Sound masking works best as one layer of three. Absorption reduces reverberation and makes the space comfortable. Enclosure — rooms and booths — handles conversations that need to be private. Masking covers the middle ground, reducing distraction from ambient speech across an open floor.

Getting the order wrong is expensive. Installing masking on a reverberant floor with no private spaces treats the symptom while leaving both underlying problems in place.

Practical considerations

Before specifying

Levels are typically set between 42 and 48 dBA. Below about 40 dBA the effect is negligible; above about 50 dBA people notice it and complain.

It needs commissioning by someone with a meter, not just installing. An untuned system is either useless or irritating, and both outcomes are common.

It runs continuously, which means an ongoing energy cost and a system that has to be maintained. Some acoustic booths include their own local masking; most do not, and generally do not need it because the enclosure is doing the work.

Common questions

What is sound masking?

Sound masking adds a low-level engineered background sound to a space so speech from further away becomes unintelligible. It does not reduce noise; it raises the background level so conversations blend in sooner. Systems typically run at 42 to 48 dBA, shaped to match the frequency profile of speech.

Is sound masking the same as white noise?

No, though it is often described that way. White noise has equal energy across all frequencies and sounds noticeably hissy. Masking sound is filtered specifically to cover the speech frequency range, which lets it work effectively at lower and less intrusive levels.

Does sound masking make an office quieter?

No. Measured sound levels increase, not decrease. What changes is intelligibility — conversations from a few desks away become harder to make out, which reduces distraction even though the room is technically louder.

Does sound masking provide speech privacy?

Not confidentiality. It increases the distance at which speech becomes unintelligible, which helps with distraction, but someone nearby can still hear a conversation. If a conversation must not be overheard, that requires an enclosed space rather than masking.

Do office pods need sound masking?

Generally not. A Class A booth already reduces speech by around 30 dB, so the enclosure is doing the work masking would otherwise attempt. Some premium booths include local masking as a feature; it is an addition rather than a requirement.

Related: NRC rating · reverberation time · acoustic booths · full glossary

Specifying an acoustic booth?

We publish airflow, speech level reduction and weight figures for every model, and we will send the test report references if you ask.

See the rangeBuyers guide