What is a sound masking system?

In general, the purpose of a sound masking system is to provide for greater conversational privacy (and therefore improved productivity for those not involved in the conversation) in an open office environment by adding ambient noise and shaping the noise signal to mask speech. The noise signal is fed from a specially designed generator and amplifier to the sound masking (SM) speakers. Typically, these speakers are positioned out of sight above ceiling tiles in plenum space, although speakers are sometimes used in open architecture truss type ceilings. Sound masking speakers, generators and amplifiers are typically sold separately.

How does sound masking work?

Many people believe electronic sound masking systems cancel unwanted sounds but that’s not the case. Unlike technology used in some headphones (which cancels unwanted sounds in the confined space of an ear muff), that technology does not work on the scale of an open room. Instead electronic sound masking systems add ambient noise to an open area. A specially filtered audio signal, described by the NC-40 Contour, increases ambient noise to effectively mask speech, making it more difficult to be understood.

What’s sound masking noise?

Electronic sound masking systems are often called “white noise systems” or “pink noise systems” but neither term is technically correct. White noise (for audio use) is defined as “equal sound energy at each frequency over the usable audio spectrum.” Pink noise is defined as “equal sound energy per octave over the usable audio spectrum.” By definition an octave is a doubling of frequency, so between 20Hz and 40Hz is an octave, between 40Hz and 80Hz is an octave, and so on. That means that compared to white noise, pink noise has much less energy in higher frequencies than it does at lower frequencies. Since human ears work in a logarithmic manner, pink noise sounds flat to the human ear, while white noise sounds overly bright. In other words, because of the nature of human hearing, to us it sounds like pink noise has as much energy in low frequencies as high frequencies even though that is really not the case. A sound masking system doesn’t use white or pink noise but instead incorporates a very specific filtered noise (described by the NC-40 Contour) that has been proven scientifically to produce the maximum speech-masking effect.

What does SM noise sound like?

Most people say it sounds like an air conditioning unit blowing.  In fact, office workers have been known to put on sweaters and other extra clothing when a sound masking system is introduced to an office area because they think that the air conditioning unit is constantly running.

More information?

Download the white paper Sound Masking System Design for the Integrator