Better Communication and Productivity02 March 2017 / by Peter Janis (author) / Vancouver
Primacoustic CEO Peter Janis discusses the quality of sound and sound insulation in commercial and public buildings.
Haven't we all experienced a noisy restaurant where it has been impossible to sustain a conversation? Or visited an airport where we have been unable to understand an announcement over a paging system? Or attended a school function where the echo has been so pronounced we've given up even trying to make sense of what was being said? The term used to describe the problem is intelligibility (or, more accurately, absence thereof).
Returning to the example of the restaurant, the reason we often find it difficult to sustain conversations is the tendency of patrons to compensate for background noise by raising their voices - which, triggers a series of responses as waiting staff will invariably speak more loudly, music systems will typically be turned up, and sound pressure levels will intensify further as sound waves reflect off hard flooring, walls, windows, ceilings - before echoing back into the restaurant space to produce a canopy of noise. The acoustic energy thus generated surpasses the room's ability to dissipate it and in contrast to outdoor areas where sound travels into space, the noise is left with nowhere else to go.
Moreover, the problem is the same (almost) regardless of building type, as office blocks, convention centers, hospitals, fire stations and hotel lobbies are victims of modern construction practices that invariably specify hard concrete or tiled flooring and wall surfaces, gypsum (plasterboard) or cinder block, windows spread across rooms to let in natural light, and ceilings poured from concrete, sprayed with stipple or suspended with steel: all perfect incubators of echo.
To solve the problem, we need to provide an escape hatch for the energy. This is done by mounting acoustic panels to the wall surface. The preferred acoustic panel is made from high-density 6lb per cubic foot glass wool as these absorb energy across the audio spectrum in a more uniform manner and are particularly effective in the voice range. Each panel is surfaced with micromesh and has resin hardened edges to prevent dusting. The panel is typically jacketed in an acoustically transparent polyester tweed for easy cleaning with a vacuum. Sound energy - in the form of vibrations - penetrates the panel causing the minute fibers to vibrate, essentially converting sound energy into heat, creating the all-important energy escape hatch. The science is known as thermodynamics. As a rule of thumb, applying acoustic treatment to between 15% and 25% total wall surface will deliver exceptionally good results. Mounting acoustic panels on the walls is done using Impalers and is as easy and hanging a picture. Installation is so simple that it can be done by maintenance staff. A new generation of paintable panels is now available that enables the pre-painted white panels to be re-painted on site using standard latex to match the room’s décor. One can also transfer digital images to them in order to camouflage them into art.
In facilities where wall space may be limited, suspending acoustic clouds or baffles from the ceiling affords a very effective alternative. This is easily done using eye hooks and adjustable SlipNot aircraft suspension cables. Clouds are suspended horizontally and take less vertical space while baffles are suspended vertically and most often placed up in the rafters or beams. Both the direct sound from the floor and the early reflections from the ceiling are absorbed by the two sides of the panel making them twice as effective at reducing the reverberant field. When solving acoustic challenges in larger spaces such as convention centers, gymnasiums or auditoriums, a combination of wall mounted and ceiling panels is generally used. In smaller spaces such as boardrooms, classrooms, and call centers, wall mounted acoustic panels tend to be preferred due to limited available ceiling height, lighting fixtures and HVAC ducts. Placement of the acoustic panels is not critical as the noise is omnipresent. For safety, insurance and legal peace of mind, it is important to consult the manufacturer’s web site to verify that independent laboratory tests have been conducted to ensure the proposed panels will pass local building codes. These include EN 13501-1 designation for Europe, ASTM-E84 in the United States and Can/UL S102 in Canada. These test standards provide data on flame spread and smoke density which of course are essential in today’s ever-more litigious society.
Today, so much business is done through collaboration. This can be in the form of huddle spaces, meeting rooms, telephone conference or via video conferencing. A huddle space is often a dedicated area in an large open-office that enables several individuals to gather around a table. These conversations can sometimes be boisterous and interfere with nearby co-workers. And just as the noise in a restaurant self-perpetuates, as voice levels in the open office increase, so do the co-workers on phones or having meetings to compensate. The disruption causes undue stress, a lack of concentration and productivity falters. A good solution here is to mount acoustic clouds above the huddle space in order to inhibit the noise caused by the meeting from echoing throughout the larger office space.
When a telephone or video conferencing system is introduced, the problem is more pronounced. Sound is made up of vibrations that travel through various mediums such as air, water, windows and even concrete walls. When sound hits the ear drum (diaphragm), the vibrations are converted to electrical impulses that the brain recognizes as speech, music or noise. Our remarkable brain is able to discern conversations even when the ambient noise is extreme. It does so by localizing the sound using our two ears, comparing other clues such as reverberation and tone, reading lips and watching body language. For the most part, this enables us to ignore the noise and decipher what is being said. When sound is captured a microphone (also a diaphragm) it picks up everything that is making noise including the HVAC system, outside traffic, the echo in the room and background chatter. It has no way of deciphering what is important and what should be ignored. When it is transmitted to another party via a loudspeaker or telephone, the sound is flattened out. All of the subtleties are lost, we are no longer able to localize the voice versus the unwanted distractions and intelligibility is compromised. At the receiving end, we do our best to concentrate, but to no avail. We get frustrated, tire out, our attention span wanes and the important message is lost. Broadcasters have known of this problem for decades and is the reason they treat their studios with acoustic panels. There is no point in transmitting a message if it is difficult to understand.
Probably the most important aspect of acoustic treatment is how it may affect life safety messaging. In the event of a fire, evacuation or other catastrophe, it is imperative that the public-address system (PA) be able to perform properly so that important messages be understood. Facilities with a long reverberation time (RT) are certain to pose intelligibility problems. Bringing the RT down to below 1 second (approximately 700 milliseconds) will solve the problem. This will not only prove to be essential in times of need, but reduce the ambient noise during regular business which in turn will make for a more comfortable working environment. A 2014 study conducted by Ipsos on behalf of furniture manufacturer Steelcase found that workers lost as much as 86 minutes per day due to noise distractions such as co-worker discussions, phone conversations, a loud printer, HVAC system, or the ring of a cell phone. It is well documented that providing employees a with a heathy workspace will improve productivity, lower stress and reduce absenteeism.