10. The machine-readable medium of claim 7 wherein the plurality of speech segments are stored in a voice table.
7. A machine-readable non-transitory storage medium having instructions to cause a machine to perform a machine-implemented method comprising: pruning redundancy of instances in a plurality of speech segments, wherein the redundancy criterion is based on a similarity measure between feature vectors derived from a machine perception transformation of time-domain samples corresponding to the instances in the plurality of speech segments, wherein the instances subjected to redundancy pruning are clustered together with feature vectors discernably separated from each other in the machine perception transformation, wherein the machine perception transformation is correlated with human perception by using the time-domain samples retaining both amplitude and phase information of the speech segments, which were provided in sound data for a speech synthesis system, and wherein the redundancy pruning is performed on a representation of voice units, the representation being stored in a memory of a data processing system which includes a processor which performs the pruning.