5. A method of recognizing a received phoneme, the method comprising: generating an expanded received-signal vector from a received-signal vector associated with a received phoneme; transforming via a processor the expanded received-signal vector into an orthogonal form associated with a hypersphere having a center and a radius; determining a first distance associated with the orthogonal form of the expanded received-signal vector and a second distance associated respectfully with each orthogonal form of expanded stored phoneme vectors; and recognizing the received phoneme according to a comparison of the first distance with the second distance.
7. The method of claim 5 , wherein transforming the expanded received-signal vector into an orthogonal form further comprises: setting [y k ]=[z k ]ΛV t , where y k is a k th acoustic vector for a corresponding received phoneme, z k is the corresponding orthogonal vector and Λ and V are diagonal and unitary matrices, respectively.