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Publication Citation: Guide to Test Methods, Performance Requirements, and Installation Practices for Electronic Sirens Used on Law Enforcement Vehicles

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Author(s): Randall P. Wagner;
Title: Guide to Test Methods, Performance Requirements, and Installation Practices for Electronic Sirens Used on Law Enforcement Vehicles
Published: August 01, 2000
Abstract: Sirens are devices that produce warning sounds. Siren sounds are intended to help alert the public that an emergency vehicle (e.g., police car, ambulance, fire truck) is nearby and responding to an emergency. These sounds should be recognized as the call for the right-of-way of the vehicle. There are three types of emergency vehicle sirens: electronic, mechanical, and electromechanical. Mechanical and electromechanical sirens are powered by a mechanical connection to the vehicle drive train or an electric motor. These sirens produce sound by pumping air through a perforated disk revolving in front of a fixed structure with ports. As the disk turns, the perforations pulse the sir flow through the ports. The successive pulses of air produce the familiar mechanical siren sound, which modulates in frequency and amplitude as the disk and air flow speed up, and slow down. An electronic siren is a system of components that includes one or two electronic siren loudspeakers (seldom more than two) and an electronic siren amplifier powered by the vehicle electrical system. Most sirens sold for law enforcement vehicles are electronic. The size of most electronic siren loudspeakers permits them to fit in smaller spaces than mechanical and electromechanical sirens. This guide is written for persons who select, install, or operate electronic sirens on law enforcement vehicles, or instruct those who do. It discusses the contents of several documents, listed later in the guide, that specify test methods, performance requirements and installation practices for electronic siren systems. The goal is to familiarize law enforcement personnel with these documents and the documents and the meaning of compliance with each one. Apart from this issue, the basic characteristics of electronic siren systems are discussed, as well as special features and installation options. The related issues of occupational hearing loss and exposure to siren noise are also addressed. All of the material presented in the first five sections of the guide is fairly basic in nature. Technical details are limited to section 6. Keywords: electronic sirens , emergency vehicle sirens , police sirens , sirens , siren tests , vehicle siren installation , vehicle siren measurements , vehicle siren requirements
Citation: National Institute of Justice Guide
Volume: NCJ 181622
Keywords: Acoustics;law enforcement;sirens
Research Areas: Acoustical pressure measurement