SUMMARY REPORT ON EMERGENCY VEHICLE SIRENS - LAW ENFORCEMENT STANDARDS PROGRAM

• NCJ Number: 15245
• Author(s): F E JONES; T L QUINDRY; W J RINKINEN
• Date Published: 1974
• Length: 48 pages
• Sponsoring Agency: US Dept of Justice; US Dept of Justice NIJ Pub
• Corporate Author: US Dept of Commerce; US Dept of Justice
• Sale Source: Superintendent of Documents, GPO; National Institute of Justice/
• Publication Type: Best Practice/State-of-the-Art Review
• Language: English
• Country: United States of America

Annotation

THIS PROGRAM WAS DESIGNED TO IDENTIFY AND QUANTIFY THE PHYSICAL PARAMETERS OF THE VEHICLE EMERGENCY WARNING DEVICES, AND TO DETERMINE THEIR EFFECTIVENESS IN ENABLING POLICE TO SAFETY AND EFFICIENTLY PERFORM THEIR DUTIES.

Abstract

IN THIS SUMMARY REPORT IT HAS BEEN SHOWN, BOTH THEORETICALLY AND EXPERIMENTALLY, THAT INTERFERENCE CAUSED BY REFLECTION OF SIREN SIGNALS CAN RESULT IN A DECREASE IN SOUND PRESSURE LEVEL OF AS MUCH AS 60 DECIBELS AT CERTAIN SPECIFIC SIREN-TO-SUBJECT DISTANCES. TO ILLUSTRATE QUANTITATIVE AGREEMENT BETWEEN CALCULATED AND EXPERIMENTAL DATA, A TEST PROGRAM INVOLVING 23 TEST AUTOMOBILES, 4 ELECTRONIC SIRENS AND 9 ELECTROMECHANICAL SIRENS HAS BEEN COMPLETED. MEASUREMENTS HAVE BEEN MADE OF THE DIRECTIONAL RESPONSE AND SPECTRAL DISTRIBUTION OF THE SIRENS, OF THE TRANSMISSION OF THE AUTOMOBILES, OF THE MASKING NOISE IN THE AUTOMOBILES WHILE BEING DRIVEN OVER A TEST ROUTE OF FOUR DIFFERENT SEGMENTS, AND OF THE PHASE CANCELLATION PATTERN FOR AN ELECTRONIC SIREN. MEASUREMENTS OF DIRECTIONAL RESPONSE WERE MADE ALSO FOR A PAIR OF ELECTONIC SPEAKERS IN THREE DIFFERENT ARRANGEMENTS. THE DIRECTIONAL RESPONSE AND SOUND POWER MEASUREMENTS WERE MADE IN THE LABORATORY IN AN ANECHOIC CHAMBER. THE ORDER MEASUREMENTS WERE MADE IN THE FIELD. THE DATA ARE PRESENTED IN TABULAR FORM AND IMPLICATIONS OF THE RESULTS REGARDING THE EFFICACY OF THE SIREN AS A WARNING DEVICE ON AN EMERGENCY VEHICLE ARE DISCUSSED. (AUTHOR ABSTRACT MODIFIED) (SNI ABSTRACT)