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103 11.1 Operation of the PA System This chapter presents operational policies and procedures that affect the speech intelligibil- ity of PA systems in airport terminals. The installing contractor should provide an operations manual that covers how to operate the paging stations. 11.1.1 Employee Announcement Training Input from the industry and passengers reveals that training for airport staff on best prac- tices for making announcements would be valuable. Individual airports or airlines may have specific concerns or existing practices that can be incorporated or updated. Discuss the following with airport staff: â¢ Announcement composition: Be concise and use a hook. See Chapter 10. â¢ Announcement delivery: Use clear speech technique. See Chapter 10. â¢ Microphone technique: Learn how to use a microphone properly. â¢ Announcement timing: Where overlapping announcements are possible, develop standard operating procedures for employees. 11.1.2 Use of Microphones If unidirectional microphones are used, certain precautions should be considered. Some charac- teristics of unidirectional microphones make them best suited to airport PA systems. Because uni- directional microphones are less sensitive to off-axis sound than omnidirectional types, the talker should speak directly into the microphone. A change in the microphoneâs frequency response usually gets progressively more noticeable as the arrival angle of sound increases. This is due to off-axis coloration where high frequencies tend to be lost, resulting in a âmuddy,â less intelligible announcement. The talker should be an inch or two away from the microphone. Speaking too closely into the microphone decreases intelligibility. This is a characteristic of unidirectional microphones, where bass response increases when the talker is too close to the microphone. Too much bass will make the announcement sound unnatural and less intelligible. For maximum intelligibility, announcers should speak slowly and clearly. 11.1.3 Voice Quality and Microphone Technique A good-quality PA system will faithfully reproduce the human voice from microphone to loudspeaker. Older or existing systems with less desirable PA systems may require more effort by airport staff. Staff should â¢ Determine the optimal combination of microphone to mouth placement and vocal effort to achieve a sound that passengers can understand. It may be necessary to have co-workers provide feedback. C h a p t e r 1 1 Operation and Maintenance of the PA System
104 Improving Intelligibility of airport terminal public address Systems â¢ Ensure their mouths are clear of food or other foreign objectsâsuch obstructions make it difficult for passengers to understand announcements. â¢ Speak into the microphone. Some people speak from their voice box or throat, making it dif- ficult for the microphone to pick up any signal. â¢ Use clear speech technique. Do not rush; speak with a measured cadence. 11.1.4 Competing Announcements Some PA systems include a lock-out that prohibits simultaneous announcements from adja- cent or nearby spaces. Lacking such a control, especially for existing systems where loudspeakers at the edge of a zone easily broadcast into the adjacent zone or gate hold area, it is best practice to wait until the other announcement is completed. 11.1.5 Zoning Announcements Loudspeaker zoning is a useful tool in limiting announcements to areas where they are relevant. For example, limiting curbside announcements to the curbside, ticketing, and landside arrivals areas makes sense, given that gate passengers are not likely to require an announcement that their cars should not be parked at the curb. 11.2 Maintenance of the PA System This section discusses maintenance best practices. A maintenance contractor or airport person- nel should maintain the PA systems. The PA system installer should provide information on how to make level changes in the PA system. With older analog systems, more hands-on testing and adjusting is expected. With newer digital systems, maintenance tasks are reduced; many, if not most, digital systems monitor all aspects of the signal flow and will list problems in the fault log. System design and components can be specified to support built-in PA system component health monitoring and to include effective built-in test capability. If these capabilities are included in the system, appropriate training and testing on these functions should be included in regular maintenance operations. More information is provided in Sound Systems Engineering (Davis and Patronis 2014). Tasks for airport personnel and technicians include the following: â¢ Frequently checking the digital system fault log and addressing problems that arise. â¢ Periodically checking the paging stations for broken microphones or microphone cables. â¢ Periodically checking paging zones for sound level anomalies by walking the zones during announcements. (Refer to the installing contractorâs operations and maintenance manual for steps to making changes in the digital system.) â¢ Periodically checking paging zones during announcements for buzzes, rattles, or inoperative loudspeakers. Contact the installing contractor for verification and replacement. â¢ Documenting changes. (Keep track of any changes to the installed/commissioned settings to the DSP, EQ, and levels and retest to confirm conformance.) â¢ Referring to equipment manufacturersâ user manuals for operational guidelines. â¢ Cleaning. Keep the rack-mounted equipment clean and free from dust and debris. â¢ Scheduling periodic visits by the installing contractor for complete end-to-end system com- pliance with system performance requirements.