Nowadays, there is an increasing demand of measuring sound pressure level. Traffic and constructions generate big noise, because of their harmful physiological effect, there are strict rules for noise levels which are monitored. Another application of the sound pressure level measurement devices is measuring the sound pressure level of music events. There are also rules for it. Since different thresholds are set at different distances, it’s expedient to measure it with an easy-to-install, small-sized device, that sends data wirelessly to another device.
For this purpose, the IoT, the Internet of Things tools are best suited. They are connected to a server via the Internet or even interacting with each other, sending the measured values and, if necessary, responding to a signal coming from another device. I chose the Bosch XDK tool. It has multiple sensors, including a microphone, and wireless interfaces.
During my work I realized the following process. The microphone outputs a voltage value proportional to the sound pressure, sampling it with the microcontroller, and then processing the samples to get a standard dB sound pressure value. I send this via a wireless interface to another device that displays it.