Sound masking's been in use for decades, but many people are still unfamiliar with this technology. So, this week, I thought I'd tackle the top 10 questions I'm asked at tradeshows.
1. How can you cover noise with sound?
Adding sound in order to control noise seems contradictory. But the problem with many offices is that they're actually too quiet. They just don't have an effective ambient level. And in this ‘pin drop’ environment, even the smallest noises disrupt our train of thought. It’s also really easy to hear other people’s conversations, whether we want to or not. That’s why we describe these spaces as noisy.
Sound masking solves this problem by distributing a comfortable background sound throughout the space. This new baseline level – typically around 40 to 48 dBA in commercial interiors – covers up any noises that are lower in volume than itself and reduces the disruptive impact of those that are higher by minimizing the amount of volume change that occurs.
We’ve all experienced this effect at one time or another. For example, think of the time you were trying to talk to someone in a busy restaurant. The ‘hum’ of all of the other conversations happening around your table probably made it difficult for the other person to easily hear what you were saying. It also made you less likely to jump out of your seat when the waiter dropped a glass in the kitchen.
Of course, this is an extreme example. When introducing a masking sound to a workplace, you don’t want a hum or a whoosh or a buzz. If the system is properly designed and tuned, people usually compare the sound to softly blowing air. It’s subtle, but very effective.
2. Can I use my airflow system to provide masking?
Your airflow system turns on and off throughout the day in order to regulate the building’s temperature. It can’t be relied on to provide constant coverage. And, when it’s on, the sound it produces isn’t at an appropriate volume or in the correct frequency spectrum to mask speech.
3. Is sound masking the same as white noise?
‘White noise’ is a specific type of sound that was used in early sound masking systems back in the 1970s. Those systems were really inflexible and people often shut them off because of the hissing quality of their sound (think of an un-tuned television set, if you’re old enough to remember them like I am). But the term ‘white noise’ was widely adopted and today it’s often used interchangeably – though incorrectly – with ‘sound masking.’
4. Is sound masking the same as noise cancellation?
‘Noise cancellation’ is another well-known term thanks to the popularity of headphones offering this feature. In more traditional applications, this technology uses microphones to detect a noise, which signals a computer connected to a loudspeaker to produce an equal and opposite sound wave. This wave is projected in the same direction as the noise, largely eliminating it. It’s most effective for continuous, low-frequency sounds like engines and traffic.
But its applications are limited because the noise source and the listener have to remain in the same position for the effect to be experienced. Cancellation doesn’t work in an office because it can't address the variable and high-frequency nature of speech, or moving employees.
5. Will I hear the sound?
You have to be able to hear the masking if it’s going to work, but it’s designed to be as unnoticeable as possible. The sound doesn’t contain distracting patterns and it’s tuned so you don’t hear volume changes as you move throughout your facility. Occupants come to consider it a natural part of their environment in a short period of time.
That said, in order to allow integrators to properly tune the masking sound for your space, the system must offer small adjustment zones (1 to 3 loudspeakers) with very fine volume and frequency control in each one.
Okay, this post is getting pretty long. Please tune in next week for the remaining five questions and answers...