Security Dealer & Integrator

SEP 2013

Find news and information for the executive corporate security director, CSO, facility manager and assets protection manager on issues of policy, products, incidents, risk management, threat assessments and preparedness.

Issue link: http://sdi.epubxp.com/i/172392

Contents of this Issue

Navigation

Page 50 of 119

(NEMA), states that designers and engineers have the greatest effect on speech intelligibility by their choice of equipment; the number, distribution and placement of loudspeakers; and the power at which they are driven. According to NFPA, in order to achieve an intelligible voice message in certain situations, a distributed sound level with minimal sound intensity variations is required, which differs from past fire alarm design. It is not simply a matter of turning up the volume or increasing the speaker wattage. Many poor evacuation systems are the result of trying to compensate for an insufficient amount of speakers with too much volume. The rule of thumb for enhanced intelligibility is increasing the number of speakers and using the lower tap settings instead of increasing the sound output — as increasing the wattage of a speaker can often distort the message. Optimizing intelligibility can equate to as much as eight times as many speakers used just to achieve audibility. The deal point-source (speaker to listener) is 20 feet or less. Ceiling height should be speaker spacing. For example, if the ceiling is 12 feet high, space the speakers 12 feet apart for intelligibility, as opposed to 24 feet apart for audibility. Designing for Outdoor Areas The same principles also pertain to designing intelligible systems for outdoor areas; however, there are additional parameters to consider such as wind, temperature and humidity, as well as the changing of the environment due to seasons, age and time. For example, vegetation growth affects sound. Designing a wide-area MNS in the middle of winter when trees are bare without considering trees in full bloom, can greatly affect the intelligibility of the system. Referring to NFPA 72 2013, consulting a sound professional and utilizing commercially available software tools are recommended when designing spaces and rooms for voice intelligibility. It is also important to note to include all stakeholders as part of the design process, such as the architect, interior designer and the AHJ. ❚ Ted Milburn is VP of marketing for Cooper Notification. Learn more at www.securityinfowatch. com/10215756. sit! stand! or anything in between. Create a healthier and more comfortable environment in the workplace with new adjustable Sit/Stand ViewPoint™ consoles. Improve ergonomics with height adjustments that let you change position whenever you want, helping reduce fatigue and improve concentration. Sit/Stand lift legs take no space in equipment mounting bays. And they arrive pre-installed, either in ViewPoint console bays or as a standalone work station. Like all ViewPoint technical furniture, Sit/Stand consoles ship fully welded to minimize assembly time. With 11 great finishes and fast shipment, Sit/Stand consoles are an easy, smart choice. what great systems are built on. TM racks cable management technical furniture power info@middleatlantic.com middleatlantic.com 800.266.7225 Request information: www.securityinfowatch.com/10215070 www.SecurityInfoWatch.com | SD&I; | September 2013 47

Articles in this issue

Links on this page

Archives of this issue

view archives of Security Dealer & Integrator - SEP 2013