It can be helpful to know which frequencies correspond to which notes under your fingers. This display can help you relate to devices, such as tone controls and equalizers, when amplifying your bass. However, it's extremely important to note that the character of the note does not come only from the fundamental (root) note that you're playing. There's highs in that note, and those who turn the bass frequencies up and the highs down are doing a disservice to their sound!

It's often the midrange that helps to define the sound of the upright bass; without it you may as well be playing a bass guitar. You will also find that the higher frequency components (overtones) in the note, as well as the string attack, helps you cut through the mix. The highs that provide better definition of notes are important, otherwise you just sound like the thud of that stray car riding by your house with the subwoofer blasting at 3 a.m. (note to self: buy stock in hearing aid companies).

You'll often find finger noise around 1000 hz., but be careful not to remove too much of that frequency band.