Studying  music, we can divide any composition into complementary functional groups: harmony and  melody.

The melody is the main musical line;  In short, it consists of a logical succession of sounds, by which the listener can distinguish a beginning, a development and an end. In a modern band the melody can be performed by a singer, a solo guitar or a sax.

The harmony is the progression of sounds and chords that accompany and are at the heart of the melody.
The harmonic function inside a modern band can be performed by a bass or by a rhythm guitar.
 

There are few polyphonic instruments; meaning those that are able to simultaneously play harmony and melody. 
Of these, the undisputed leader is the piano; the right hand plays the melody while the left hand plays the harmony. The guitar, as well as the bass guitar and  most of  the string instruments, are not in their standard use poliphonic instruments; while one hand is busy  pushing the fretboard to change the note, the other hand is busy strumming strings , which produces a sound.

Thumbstring is a simple innovation, born on a September morning of 2003, and has been developed until it became a patent, a mark, a product. Thumbstring was born from a personal need of mine as a musician, a need shared by my musical collegues and friends , who  encouraged me to turn a prototype into a product.

The idea was to add to the traditional string instrument  some strings on the back of the neck, with the same length of the vibrant string.
The motivation for this innovation was the desire  to play -harmony and melody easily at the same time; but thanks to the development and the potential of the instrument, I - soon recognized it has many possibilities.

Thumbstring is a new and simple concept of string instruments;  It allows you to play in a polyphonic way, or it simply enriches the harmonic and melodic function in a simple and intuitive way.
It doesn’t necessarily require a special technique; it is built on a standard model string instrument (bass or guitar) and it retains the sound and the performance of the instrument. Thumbstring isn’t a substitute for the traditional instrument; it simply adds another way to create music, which is at my disposal to- use however I wish.

The Thumbstring bass player can free himself from the responsibility of keeping chord root and take the liberty of adding parallel and harmonized fills or bass lines. The bass player can venture in polyphonic constructions, keeping within an harmonic pedal, and building on that a melodic line, exploiting the sound and - potential- of the instrument. The bass player can also exploit, through different tunings, the harmonic potential of chord sounds, to obtain for his own melody an harmonic backing, based on more sounds. Thanks to the separate electronics, which allows the split and the differentiated use of the front and the back -, he can create, with an effect or multieffect, two lines with two different sounds.
Eventually, the Thumbstring bass player can use his instrument like a traditional bass, with the same characteristics of technique and sound.

The Thumbstring guitar player, whose role inside the band is accompaniment, or back up,  can free himself from the responsibility of keeping the harmony, adding more freely parallel and harmonised fill or chords.

The guitar player can venture in polyphonic construction, keeping within an harmonic pedal and building on that a melodic line, without the help of the bass player.
Thanks to the separate electronics, which allows the split and the differentiated use of the front and the back part, he can create, with an effect or multieffect, two lines with two different sounds.
Eventually, the Thumbstring guitar player can use his instrument like a traditional guitar, with the same characteristics of technique and sound.

The technique of use may seem complex, but it’s actually very easy, I think everyone should try it !
It consists in the use of the left hand thumb ( which is normally not used) to press a string which is in the back of the neck, the thumb-string. Just like the tapping technique, the string resonates alone, producing a continuous basic sound on which you can freely play another line with the front strings.

In  contemporary music history we can find some forced techniques, which allow- the musician to create polyphonics in a similar way as Thumb-string does, on traditional string instruments.
The easiest way is to strum the strings, those strings which are not used for the melody; despite a good effect, the harmony is linked to E, A, D and G tonalities.

Other musicians whose hands are especially big (- like Jimie Hendrix), achieve the same result by using the lower strings with the left hand thumb in a forced position; but this is a  much more complex technique.
Lastly, the tapping technique, for which special instruments are used, allows very complex polyphonics to be created; but a lot of practice is required, and there is an alteration of the sound and - standard function - of the instrument.

In any case Thumbstring doesn’t necessarily replace all these techniques: it just offers another possibility to the traditional potential - of a stringed instrument, which can be used or not, as you desire.