Why Sound Masking?Any organization’s greatest asset is giving the people they employ the ability to think and do their work. Individuals produce their best work in a stress-free, comfortable environment, yet without proper acoustics, this environment is unattainable. Sound masking ensures speech privacy and comfort within the designed environment, allowing collaborative and individual workspaces to co-exist. Today’s workplace design is creating more open, collaborative environments and is reducing the number of closed offices and group workspaces. In addition, the trend is toward more energy-efficient, utilizing greener materials such as reclaimed woods, metals, and glass. But these are hard surfaces that reflect sound. As a result, designers are trying to minimize sound absorption materials such as carpet, fabric partitions, and even acoustical ceiling tiles in workplace design. Sound masking manages sound while creating more comfortable environments in which to work.
What Is Sound Masking?Sound masking changes the speech-to-noise ratio within a space. When properly designed, sound masking gently raises the ambient background sound uniformly with a clean, consistently random, broadband, non-intrusive sound. In essence, it dynamically improves comfort and collaboration in the workplace. Individual ceiling speakers amplify the scientifically engineered sound throughout the space to create a uniform field of sound, ensuring temporal and spatial uniformity. By filtering down into the area below, the sound masking system “fills” the plenum and gently raises the background sound level to cover or mask unwanted office noise.
Types of SystemsThree system types exist for sound masking: When engineered to meet a facility’s specific needs, networked systems provide:
- Superior sound quality.
- Extreme design flexibility.
- One point of control.
- Virtually limitless zoning capabilities.
Speaker OrientationTraditional office layouts allow for the indirect firing of speakers, the preferred manner of filling the plenum with sound to provide more efficient and uniform masking. However, alternative office designs sometimes create a need for direct firing or in-floor masking applications, which, when appropriately designed, can still achieve privacy and comfort.
Key CriteriaA quality sound masking system must address both Speech Privacy and Comfort to be effective for your space.
Speech PrivacyThe primary purpose of a sound masking system is to make conversations private and less distracting. Intrusive noise is a common employee complaint in today’s workplace, and loss of confidentiality from overheard speech is a top concern for executives; sound masking addresses the need for speech privacy. There are a variety of methods for measuring speech unintelligibility. The “Standard Test Method for Objective Measurement of Speech Privacy in Open Plan Spaces Using Articulation Index,” ASTM E-1130, is the primary test to determine speech privacy. In essence, this test measures the percentage of an understandable sentence, resulting in ratings on the Articulation Index (AI). If the AI measures .20 or below, an individual cannot make out more than 20% of a conversation, and you have effectively achieved speech privacy. Confidential Speech Privacy occurs at an AI of .05 or less.
ComfortComfort in speaking is just as important as achieving speech privacy. Most individuals would prefer comfort over privacy if given a choice. Fortunately, they do not need to choose. Following are the criteria for delivering a comfortable sound:
- Full Broadband Sound – the origin of the sound should cover the entire spectrum from 65 Hz to 13 kHz. Speech comfort comes from masking a full broadband spectrum since systems that only mask a portion of the spectrum cause fatigue and discomfort.
- Wrap Around – Sound masking should be nonrepetitive. When something has a pattern, our brains recognize it as information to monitor, which in turn fatigues us.
- Multiple Noise Sources – randomness is created by using many noise sources.
- Uniformity – background sound must be consistent and level throughout a space. Sound masking is noticeable and distracting if there are hot and cold spots.
- Tuning Flexibility – a system should easily allow volume and contour adjustments to meet the criteria of privacy and comfort of the space. Depending on the number of people in an area, the sound masking may need to be louder or softer. Additionally, individuals have their preferences; therefore, easy adjustments are critical.
For smaller spaces
For larger spaces with multiple zones