What ever sound you want it to make! The Eigenharp comes with a range of samples including 1500 AIFF format (timestretch and tempo change capable) varied Percussion and Drum loops, Sampletekk 'Black Grand Steinway D, Sampletekk 'Tubed Rhodes', Camel Audio's Eigenlabs Player version of "Alchemy" and not to mention our own physical models of a Cello and Clarinet. The EigenD software is also capable of using any 3rd party SoundFonts, sample instruments and Audio Units (AU's).
The software and sounds all run on your computer. The Eigenharp itself does not have sounds, software or processing built into it, meaning the instrument hardware itself will never go out of date.