A reminder when selecting test equipment: components have various levels of calibrated tested precision. There is often a good reason why some devices cost more than others. You should carefully check the equipment specifications as to what is required by your AHJ, and make sure the equipment you select meets those testing performance criteria.
While we have mainly emphasized testing guidelines, I would like to offer a few speech intelligibility performance suggestions. How can you improve speech intelligibility if you have poor test readings? Some ideas: use more speakers at lower wattage taps; calibrated amplifiers; speakers 20 feet or less from listeners; have all speakers in phase; audio wiring with an audio twist; correct speaker spacing to ceiling height; and checking reference standards such as NFPA.
A special thanks Gold Line’s Mathew Miller for contributing a variety of valuable training and technical resources for this article. He also mentioned the company will have a new and updated set of online training videos to look forward to this fall. Keep an eye out for that and learn more about opportunities in MNS speech intelligibility.
Bob Dolph has served in various technical management and advisory positions in the security industry for 30+ years. To share tips and installation questions, E-mail Bob at firstname.lastname@example.org. Check out his Tech Shack blog at www.securitysales.com/blog.
Tech Talk Tool Tip
Remember, speech intelligibility is not a physical quantity like amperes, volts or BTUs. It is the degree to which we understand spoken language. This month I have selected the Gold Line DSP2B system for speech intelligibility testing and recording. The kit comes with the company’s Platinum software shown here.
STI measurements can be made without significant training. Once the STIPA signal has been inputted to the system under test, a single button push on the DSP2B/BP will produce the STI, which can be converted to CIS as specified in IEC standard 60849. The test only requires about 15 seconds.
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