Essentials of Effective Speech Privacy: The Importance of Speaker Placement

speakerWhy Would Anyone Do That?

To illustrate the importance of speaker placement, consider the following scenario: You hire a contractor to install a high-end music system in your office. The anticipation of hearing the crisp sound from those quality speakers makes your morning commute a little quicker. But when you arrive, you find that the installer put the speakers above the suspended ceiling, in the plenum. The great sound you expected from those speakers just isn’t there. You call the installer back and insist the speakers be mounted into the ceiling tiles, emitting the music directly into the room. But what if the contractor responded to your objections and said, “Oh – don’t worry! We’ve come up with some really high-tech ways of compensating for the impact of the plenum on the sound. We can wire the speakers in groups of 3, adjusting each zone independently to reduce variances, or better yet, we could computerize the system. Each speaker would be assigned its own IP address so we can more precisely tune the system to compensate the acoustic problems (well – more or less) across the office area!” “That sounds like a complicated solution to a simple problem,” you think to yourself. “Why go to such extreme lengths and install such unnecessarily sophisticated equipment just to overcome basic, self-imposed design problems? Wouldn’t it be better to just put the sound directly into your office space? Besides, why not keep it simple and avoid needless potential points of failure?

Technology Choices

This scenario describes the two general categories of sound masking systems available to you at present. Over 40 years ago, indirect field systems began putting the masking speakers in the plenum because it worked best with the speaker technology of that time. Over the years indirect field systems have introduced new and increasingly sophisticated means of compensating for the problems related to speaker placement. One of the most recent uses a computerized system, where each speaker is assigned an IP address and can be adjust via a computer. While this is the most adjustable indirect field system to date, you still have to wonder:

Why don’t they take advantage of the latest technology?

Could it be that like many institutionalized solutions they continue in their current path because – - “that’s the way it’s always been done”? By thinking “outside the box”, and taking advantage of the latest speaker technology, the VoiceArrest™ Speech Privacy System – utilizing Direct Field Technology – eliminates virtually all the challenges faced by the old style technology. Rather than developing more sophisticated means to compensate the problems caused by incorrect speaker placement, the VoiceArrest™ System addressed the root cause of the problem – the speaker placement. The results of this seemingly-simple change cannot be overstated. To illustrate the benefits of this new paradigm in sound masking, click on the demonstrations below

Putting speakers in crowded plenum spaces presents many acoustic challenges

Putting speakers in crowded plenum spaces presents many acoustic challenges (click to animate)


The VoiceArrest System bypasses those challenges, emitting the masking directly into the treated area (click to animate)

The VoiceArrest System bypasses those challenges, emitting the masking directly into the treated area
(click to animate)

Figure 1 above illustrates the difficulty in achieving good uniformity with an older-style above-ceiling system. The assumption is that the ceiling will “spread out” the sound in the plenum, improving the uniformity. What actually happens is that the plenum typically causes a lack of uniformity.Plenums hide large structural elements, such as HVAC ductwork or structural beams, which effectively compartmentalize the sound. Even if the plenum is atypical and contains no large elements, openings in the ceiling for air returns and lighting fixtures permit proportionately more sound to be emitted below them. By contrast with an above-ceiling system, the uniform gray in Figure 2 illustrates the good uniformity possible with an in-ceiling background sound system. By properly choosing emitters or speakers with ultra-wide dispersion, the background sound exhibits greater uniformity at the listener’s ear elevation (variability of less than 1 dB).

Continue on to Essential #2: Consistent Sound >

Ready to find out how the VoiceArrest™ Speech Privacy System can raise the privacy levels of your workplace? Contact one of our acoustic consultants today!