Compressor
The Compressor is a variable gain device, where the amount of gain used depends on the level of the input. In this case, the gain will be reduced when the signal level is high that makes louder passages softer, reducing the dynamic range. This effect equals to dynamic volume regulator and makes loud sounds quieter, and quiet sounds louder.
In the Properties Window you can change the effect properties. It's possible to select the necessary preset from the dropdown list or set custom values for Threshold, Ratio, Root Mean Square (RMS) and Post Amplify.