In single-channel feedforward active noise control (ANC) systems, the additive random noise-based method are often applied to achieve secondary path modeling during online operation of ANC systems. This paper investigates the issue of online secondary path modeling (OSPM) in multichannel ANC systems. It is shown that the application of existing methods for OSPM in multichannel ANC systems, greatly increases the computational complexity. This paper is an extension of our previous work for OSPM in ANC systems. It is shown that Authors' method has reduced computational complexity as compared with the other methods. The computer simulations are carried out which demonstrate the effectiveness of the proposed method.