In recent years, growing multimedia systems require more efficient signal separation methods to preserve the quality of voice or music recording under a noisy environment. Some of signal separation methods are based on minimizing the dependent measure among input signals to separate a noise component since a noise component is usually independent on the other signals. Under such circumstances, we have developed a new method to separate independent signal components, which directly minimizes the Kullback-Leibler divergence by a genetic algorithm (GA). In this paper, we have proposed an improved method using differential information. As the result of the simulation, the separated signals are clearly separated to original signals.