April 22, 2022 - Speech privacy is the inability of an unintentional listener to understand what you are saying. In a mobile and technical environment it is extremely easy to have part or all of a conversation exposed to the unintentional listener. The use of smart phones and video conferencing exemplifies these types of conversations. This exposure can be concerning to the one having the conversation and also distracting to the listener not engaged in the conversation. The notion of speech privacy is to reduce the amount of a conversation that can be overheard as well as minimize the level of distraction that the same discussion can create.
Why is Speech Privacy Important?
Whether the conversation is a negotiation, a Human Resources matter, private company information, or a doctor-patient discussion, privacy of information matters. There is a certain sensitivity to some confidential conversations that you just don't want to be overheard by others. These are obvious cases for why speech privacy is important. However, in an office setting, there is another need for speech privacy – productivity. Overheard discussions can cause distraction for the unintentional listener which can reduce focus and draw them away from the work they are intending to achieve. Studies show that for every workplace distraction it can take an average of 25 minutes to return to normal production levels. That means one distraction per day consumes 5.2% of an 8-hour work day. And, that is only ONE distraction. Excessive noise from conversations can be troublesome, irritating and distracting for individual workers.
In all healthcare facilities – large and small – the Health Insurance Portability & Accountability Act's (HIPAA) primary goal is to protect patient privacy and confidentiality. This is incredibly important as it relates to speech privacy. Whether in a reception area or an exam room, protecting sensitive information, from your social security number or insurance information to a diagnosis, is extremely important and most of this information is delivered verbally.
In a research paper produced by Knoll in 2019, Sound Privacy was the number one complaint employees reported having in an open plan environment. Employees are distracted and dissatisfied by noise in their personal work space. And, with the trend towards more open workplaces in order to maximize real estate expense there is the potential for noise to exacerbate this problem.
It is important to safeguard private conversations. HIPAA guidelines are in place to protect patient privacy. But there is not a similar safeguard in the corporate office environment. Whether someone is discussing financial information, competitive situations, or organizational changes, there is a seriousness, and potentially legal requirement, to keep conversations private.
Acoustical condition studies show productivity improvements range anywhere from 3% to 51% with the introduction of noise control solutions such as sound masking solutions. A conservative example which assumes a 3% increase in productivity, for 20 fully loaded employees making $ 50,000 a year (assume a 20% overhead expense), would deliver a return within two and a half months. See our ROI guide for more details.
Office Acoustics
So how do we manage sound within a facility? The most common principal is known as the "ABCs of Acoustics." "A" is to absorb. Speech, like any sound, travels in a wave and can be absorbed by soft materials such as fabrics, carpet and acoustical ceiling panels. "B" is to block. Blocking occurs with hard surfaces and no penetrations. Examples of materials used to block noise are gypsum or glass walls. Last, "C" is to cover. Covering is accomplished by raising the ambient background sound just above the noise level. The most common example is the introduction of sound masking, which is a pseudo-random noise generated within a specific range of frequencies to cover, or mask, human speech frequencies.
Interior design trends have produced more open spaces with metal, glass, and reclaimed wood materials while eliminating the usage of fabric partitions, carpet and acoustical ceilings. Furthermore, as material and labor costs have risen for decades, construction practices have seen the elimination of wall being built from the floor all of the way to the deck; now, walls are constructed to the ceiling height which exposes the entire plenum (the space between the ceiling tile to the deck above) to sound travel. Instead of creating endless meeting rooms for private conversations, sound masking systems produce similar benefits in reducing distractions for much less hassle. Speech privacy in the business environment has been strained by the removal of the "A" and "B" of the "ABCs" which leaves using a sound masking system as one of the best ways to manage noise within an office environment.
Speech Privacy Levels
Speech privacy is usually assessed based on how much of the conversation you can understand. Our brains are powerful machines and become distracted when we can understand more than 20% of a discussion. ASTM International has produced a test standard/process for measuring speech privacy, it is ASTM E1130-16: Test Method for Objective Measurement of Speech Privacy in Open Plan Spaces Using Articulation Index. There is a scale for the Articulation Index (AI) which ranges from 0.0 – 0.04 Confidential Speech Privacy, 0.05 – 0.2 Normal Speech Privacy, to values greater than 0.2 where there is little to no speech privacy. Once you hit an AI of 0.4, you have no speech privacy and will be very distracted by conversations.
What is the Best Way to Achieve Speech Privacy?
In a normal conversation, we speak at about 65 decibels (dB), which is the measurement for loudness of sounds. As you get to about 7 feet to 12 feet from that conversation, which, as an unintended listener the conversation becomes indirect speech, the dB level drops to about 46 decibels.
One way to achieve speech privacy is to introduce sound masking into the space through speakers. Sound masking does not act like a
"cone of silence" but rather introduces a gentle, low level, ambient background sound just above the indirect speech level at 47 – 48 dB. This covers, or masks, the indirect speech noise with a sound that keeps the AI below 0.2. Through the use of a sound masking system you achieve three goals, if done right:
1) Create Speech Privacy for those having conversations that don't want to be overheard
2) Increase Productivity by reducing the opportunity for distraction for the unintentional listener
3) Improve the Comfort of the space with the introduction of a pseudo-random noise that makes the space "feel" like an environment you want to work within.
