This article presents the design and implementation of a noise level monitoring system based on the Internet of Things  (IoT)  technology.  MSP32P401R,  a  high-performance  and  low-power  consumption  microcontroller  of  Texas Instruments,  is  used  to  execute  a  dedicated  C  program  that  controls  the  sampling  process  of  the  sound  stream  from  a MEMS  microphone  and  then  computation  the  corresponding  sound  pressure  level  in  decibels.  The  obtained  data  is encapsulated, uploaded, and stored into a Firebase real-time database using a NodeMCU ESP8266 module for the Internet connection.  The  noise  level  values  and  also  the  results  of  data  analysis  and  statistics  are  visualized  as  charts  allowing people to rapidly observe and evaluate the noise level in the surveyed area. The initial results of this study can be extended to set up an automated system for surveillance and alert of noise pollution in smart cities.