Design and Realization of Microcontroller-based Sound Level Meter Calibration Devices

Abstract

A noise measurement device is a sound level meter. A measurement device, like the sound level meter is best calibrated first, so the user knows how precise the device is. In association to the usage of the measuring device, several cases of different measurement results have occured. Those cases can be resolved by calibrating the device. Calibration is a set of actions that form a relation between the value displayed by the measuring device or system, or a value represented by measuring material, with known values related to values measured in certain condition. The design and realisation of the sound level meter is done automatically without moving the measuring point’s selector. This device utilises processing modules, Wi-Fi modules, a dashboard on a laptop and a Band Pass Filter (BPF) module. The BPF module on this device will function as a filter that releases certain frequencies at certain ranges and atenuate the signals with frequency outside the range. The BPF module will wilter sound sources coming from the software, DAQARTA, which has already been installed to the laptop. The sound source is an input for this calibration device. The sound that has been filtered by the BPF module is passed on to a speaker, which is an output from the designed device and measured by the sound level meter that has received a calibration certificate by LIPI. The device can fulfil the standards of ISO/IEC 61672-1 : 2017 “Electroacoustic-Sound Level Meters” at a frequency point of 125 Hz - 8000 Hz, with a value difference from the standard as much as 4,39% - 4,89%, accuracy level intensity A-weighted and C- weighted with a range of98,28% - 100% at a point of 125 Hz - 8000 Hz and precision value of 100%.