A free program for Android, by Wait What.

Bass Booster for Android is an application designed to increase bass volume. For maximum results, please use headphones or external speakers. This application is based on the Android platform, and has a user interface similar to a smartphone or tablet.

The main window contains two sliders: one for bass and one for volume. When you increase bass, you will also see a graph with three curves. Each curve represents a different frequency. When you increase volume, you will also see a graph with three curves.

There are two buttons on the right side of the screen: one for adding the selected frequency to your current frequency and one for setting the frequency to the maximum level. There is also a slider for volume.