0° and 90° Reference Directions for a Sound Level Meter

摘要

Unattended noise measurements are more and more common for noise assessment in theenvironment. Multiple sources are usually measured with a random position with respect to themeasurement point. Noise generated by ground transportation, leisure activities, constructionsites is coming from all directions, although mainly the horizontal direction. Placed verticallyand configured for a reference direction of 90° from its axis, the goal is to meet the requirementsof the IEC 61672 standard on sound level meters taking into account noise incidence from thehorizontal direction. The main technical difficulty is the criterion for the maximum leveldifference allowed between two random incidence angles (directivity). The objective can befulfilled using a cone-shaped device on top of the microphone. When measuring attended noisewith the instrument in hand, the sound level meter must be pointed at the source according tostandard IEC 60651. The purpose of the paper is to describe the different research&development phases to fulfill IEC 61672 sound level meter standard for 0° and 90° referencedirections with the same device.