A computer-implemented method for tuning a string instrument, the method comprising: storing a reference standard pitch for a string of the string instrument; measuring a pitch generated by a string of the string instrument; determining an adjustment factor based on a comparison of the measured pitch and the stored standard pitch; storing the adjustment factor for the string; generating an input signal based on measured vibrations of the string of the string instrument; generating, by a processor, an output signal for the string based on the input signal, wherein generating the output signal comprises: adjusting the input signal based on the stored adjustment factor for the string, identifying a closest reference note to a pitch of the adjusted input signal, if the pitch of the adjusted input signal is within an error threshold of the closest reference note, processing the adjusted input signal to have an output pitch equal to a pitch of the identified closest reference note, if the pitch of the adjusted input signal is outside the error threshold of the closest reference note, processing the adjusted input signal to have an output pitch between a first boundary of the closest reference note and a second boundary of a neighbor reference note such that the transfer function is continuous and linear in pitch, and outputting the adjusted input signal as the output signal for the string. storing a reference standard pitch for a string of the string instrument; measuring a pitch generated by a string of the string instrument; determining an adjustment factor based on a comparison of the measured pitch and the stored standard pitch; storing the adjustment factor for the string; generating an input signal based on measured vibrations of the string of the string instrument; generating, by a processor, an output signal for the string based on the input signal, wherein generating the output signal comprises: adjusting the input signal based on the stored adjustment factor for the string, identifying a closest reference note to a pitch of the adjusted input signal, if the pitch of the adjusted input signal is within an error threshold of the closest reference note, processing the adjusted input signal to have an output pitch equal to a pitch of the identified closest reference note, if the pitch of the adjusted input signal is outside the error threshold of the closest reference note, processing the adjusted input signal to have an output pitch between a first boundary of the closest reference note and a second boundary of a neighbor reference note such that the transfer function is continuous and linear in pitch, and outputting the adjusted input signal as the output signal for the string. adjusting the input signal based on the stored adjustment factor for the string, identifying a closest reference note to a pitch of the adjusted input signal, if the pitch of the adjusted input signal is within an error threshold of the closest reference note, processing the adjusted input signal to have an output pitch equal to a pitch of the identified closest reference note, if the pitch of the adjusted input signal is outside the error threshold of the closest reference note, processing the adjusted input signal to have an output pitch between a first boundary of the closest reference note and a second boundary of a neighbor reference note such that the transfer function is continuous and linear in pitch, and outputting the adjusted input signal as the output signal for the string.