Simply put, speech privacy is the inability of an unintended listener to understand another person’s conversation. Sound masking systems improve speech privacy through the use of an unobtrusive background sound that is not unlike airflow from the HVAC system. It is delivered by an electronic grid of speakers either in the ceiling or beneath the raised floor. Sound masking specifically targets the frequency range of typical human speech and increases speech privacy by reducing intelligibility to the degree that speech is only heard by intended listeners. In legal environments, speech privacy is critical in maintaining confidentiality. All lobbies and corridors need sound masking to prevent reception of unintended speech. Sound masking can reduce the risk and possible danger of overheard words. An additional benefit of sound masking is the reduction of distractions in the workplace which will increase focus and productivity. Law Firm Offices Law firms require the ability to have confidential conversations in nearly every square foot of their building. This includes small offices, meeting rooms, surrounding corridors, and lobbies. Even when private offices have floor to deck wall and heavy doors, this is commonly not enough to guarantee 100% privacy. Some construction techniques and building materials can reduce sound transmission, but gaps under doors, metal window frames (mullions), HVAC ducts, and plenums will allow speech transmission between these spaces.  Courthouses Some of societies most confidential conversations take place in courthouses. Jury deliberation areas cannot afford to lack speech privacy in either direction. Just as jurors need their conversations to “stay in the room,” they should likewise not be able to overhear any conversations from outside areas. Bench meetings and sidebar discussions during courtroom proceedings are made private when masking is used at the areas where the jury and audience are located. Judges are typically given a switch that will turn the masking on while also muting all microphones. Law Enforcement & Correctional Facilities These facilities are host to conversations that must be private. Meetings between lawyers and clients must remain confidential. Interrogation rooms need an “acoustic seal” around them when close to lobbies and corridors. While suspects need privacy when in holding rooms, witnesses are more likely to share information with law enforcement when they know they have speech privacy. Other areas that require confidentiality are administrative in nature. Payroll, HR, and office areas all require speech privacy throughout the day. Police stations, correctional facilities, and other municipal, county, state, and federal facilities will benefit from sound masking. 

To answer this question, you must first understand the ABC’s of masking sound which are explained in a previous blog that can be read HERE. Most Effective Once you understand the differences between Absorbing (A), Blocking (B), and Covering (C) sound, we can get into the differences in more detail. For example, methods of absorbing sound such as acoustic ceiling tiles, acoustic wall panels, and carpet are 73% effective in increasing the privacy index. Blocking methods such as cubicle partitions and constructing walls are 81% effective. But covering sound with a sound masking system is the most effective at 87%. Now, you might think that combining methods would further increase privacy and you’d be correct. But at what cost? Most Affordable Adding physical materials to absorb sound (acoustical tiles, wall panels, carpet, etc…) generally costs between $2 and $4 per square foot. Cubicles and walls not only create visually unappealing obstructions, they are an expensive method of creating speech privacy at $3 - $5 per square foot. So even if you were to use both methods as a hybrid solution, it is a fair assumption that your overall privacy index may average out to around 77%. In comparison, with a privacy index of 87%, an AtlasIED sound masking system costs around $1 - $2 per square foot. Sound masking systems are the most effective, most affordable, and most versatile solution for creating speech privacy, reducing noise distractions, increasing productivity, and improving employee comfort and satisfaction. The CBA Method So while we talk about the ABC’s of sound masking, CBA may be a better approach. First, cover the sound with the most effective and least expensive method, a sound masking system. Then use physical blocking and absorbing methods to further enhance workplace acoustics where needed. Best practice when creating optimal office acoustics includes prudent use of all three methods. For other sound masking related blog articles, CLICK HERE.

Ambient noise compensation is sometimes referred to as adaptive audio. While adaptive paging, emergency notifications, and even background music is good, adaptive sound masking may create more problems than it solves. With respect to paging, adaptivity is helpful because it makes sure that the signal-to-noise ratio is high, producing a more intelligible page. Conversely, sound masking is only effective when it goes unnoticed. Any variation in volume will call attention to the masking sound and may result in distractions and dissatisfaction with the space- the challenges that masking is designed to reduce. For example, if the masking generator was set to increase the volume of the masking “noise” as the office was fuller, and then reduce the volume when the office was less full, those working in the space throughout the day would not become habituated to the consistency of the sound. As we have mentioned before, employees and tenants returning to offices where distractions are minimized and speech privacy is upheld will result in higher employee satisfaction and productivity. Points to consider: Adaptive masking increases the radius of distraction. Conversations clear across the room can be heard as the masking is too low. It also decreases the privacy of those conversations. The “sensor” used to detect any increase in human speech is indiscriminate. The copier/printer will trigger an increase for the entire zone. The masking spectra chases the dynamics of the office noise resulting in noticeable variations in volume. The noise comes first and is then followed by the masking response. A one or two minute system response cannot cover up the beginning of any conversation. Therefore, adaptive masking can only reduce the level of privacy. It cannot increase privacy. Swings between low level and high level are obvious, annoying, and will lead to occupant discomfort. Reducing masking or turning it off is only recommended for security reasons such as night security personnel wanting to hear everything or when an emergency alert is triggered. Sound masking systems must be tuned to the environment by a professional trained in sound masking tuning. Adaptive sound masking is not tuned to the acoustics of the office space.

Speech Privacy experts, Charlie Roy and Steve Brooks, discuss the art and science of sound masking and its evolution into a digital solution that is being used to improve workplace acoustics, increase employee producitivity and satisfaction, offset the rising costs of corporate real estate, and protect confidential conversations. While some people think of sound masking as white or pink noise, it’s actually neither. Sound masking contains no information, it’s just broadband shaped noise. The low-level, electronically generated sound is designed to mask the human voice, making speech unintelligible so confidential conversations aren't overheard and other people’s conversations aren't distracting. Additionally, changes in corporate real estate have spurred more demand for sound masking solutions. Traditional office space is being replaced, by open, hard-floor environments due to cost and flexibility. Community office spaces such as WeWork, which offers collaborative workspaces that are open and full of reverberant hard surfaces, use sound masking to reduce distractions and allow occupants to enjoy a more peaceful workplace environment.  

Speech privacy / sound masking are a rapidly growing category in the commercial AV market. If you are researching sound masking you may have seen the terms indirect field and direct field to describe masking systems. How do you know which one is best for your facility so that you can make the right choice? Indirect Field Masking AtlasIED has always been a proponent of indirect field sound masking and therefore is usually the solution we recommend as long as it will work in the environment. The key characteristic of a sound masking system for it to do what it is supposed to do, is that the system appear to be invisible to anyone in the area where the masking is deployed. This characteristic is made for indirect masking where the speakers are located either above the ceiling tiles or treatments or below the floor. Since a sound masking speaker is always emitting white or pink noise it can be a distraction to people in the masking area as they can point to the speaker and say "that speaker is making noise and is bothering me." If the speaker is above the ceiling tile, as illustrated in the example below, the listeners' cannot identify the source of the white/pink noise. Additionally, installing the speakers firing up toward the deck above the ceiling tiles allows the sound masking noise to permeate the entire space and fully cover the area so there are no "dead" areas without coverage. Direct Field Masking There are some instances where indirect masking just will not work and direct field masking is the only available option. The key to a direct field masking system is trying to eliminate "dead" spots in the room so that the masking system can appear to be as invisible as possible. The below image illustrates a direct field masking system with a standard in-ceiling speaker. The speaker has a limited dispersion pattern so as is illustrated on the left side of the image, there are "dead" spots in the coverage because the speakers are spaced too far apart for the coverage pattern of the speaker to cover the listener while standing. That may not seem like a big deal because the occupants are normally going to be seated but as people move around the office they will be going in and out of the masking field, which will keep the system from