With the help of the QGIS core plugin called Heatmap, we can easily create heat maps from vector point data and use it for further analysis. First, we need to activate this plugin, if it has not yet been activated. After activation, it creates a submenu under the Raster menu and places its button on the Raster toolbar.

Let's create a density map for the noise layer, which contains information about complaints regarding high noise levels. This layer contains 44,397 features, and it is difficult to know which places are noisy.

Information about such places may be useful for a police department or other agencies to plan some activities for noise reduction, or for those who are looking for apartments and don't want neighbors who like playing loud music: