Temperature influence on noise measurements

Abstract

International experiences indicate that the temperature is a factor which has some influence on the results of measurements of road traffic noise. The On Board Sound Intensity (OBSI) method is used by University of California Pavement Research Center (UCPRC) as well as by other researchers and consultants in USA to perform detailed measurements of tire noise emission from road pavements. In Europe the Close Proximity method (CPX) is currently used. The objective of this paper is to analyze how the temperature affects the OBSI results. The results presented here are also relevant to the CPX method because the Standard Reference Test Tire (SRTT), which is the test tire for the OBSI, is being studied as a possibility for the CPX method. The analysis is based on a unique series of detailed noise measurements performed on the California Department of Transportation (Caltrans) test sections with 5 different pavements at highway LA138 in the Mojave Desert in Southern California. The measurements were carried out in the desert within three consecutive days in the wintertime where the variation of the air temperature over the day was from to 2 to 22°C. This secures that the main variable parameter during these measurements is the temperature. Based on this project the air temperature correction factor of -0.027 dB/°C for asphalt pavements can be suggested for the SRTT tire used in the OBSI method and other noise measurement methods using this tire. The temperature mainly influences the noise at frequencies above 1000 Hz, therefore it could be relevant to apply frequency dependent correction factors.