20. The computer-implemented method of claim 17 , wherein the particular transform operation comprises a VTLN transform operation that is performed on the aligned voice data using the source acoustic model.
17. A computer-implemented method comprising: obtaining, by a computer system, aligned voice data that comprises untransformed voice data in the target language that has been aligned with phonemes in a corresponding textual transcript using a source acoustic model for a source language, wherein the source acoustic model includes information that maps acoustic features of the source language to phonemes in a transformed feature space, and the untransformed voice data is in an untransformed feature space; transforming the aligned voice data according to a particular transform operation using the source acoustic model to obtain transformed voice data; adapting the source acoustic model to the target language using the untransformed voice data in the target language to obtain an adapted acoustic model; and training, by the computer system, a target acoustic model for the target language using the transformed voice data and the adapted acoustic model; and providing the target acoustic model in association with the target language.