How to adjust sound properties, like with a graphic equalizer, in Ubuntu

"There's a post on Ubuntu Forums on how you can use PulseAudio Equalizer.

Advantages:


Configurable 15 band equalizer for PulseAudio;
You can enable or disable equalized audio on-the-fly, without having to
restart any running applications;
Offers the choice of using equalized audio for the current session or
permanently;
No need to edit any configuration files by hand;
User-customizable: you can use any LADSPA audio processing plugin (which
can apply various audio effects beyond
equalization);
Packaged as a .deb file for easy installation;
Graphical User Interface."