17. A computer-readable storage device having instructions stored which, when executed by a computing device, cause the computing device to perform operations comprising: identifying an acoustic model, wherein the acoustic model is trained on native speech in a target dialect; transcribing collected speech from a speaker, to yield a lattice of plausible phonemes which depend on a property of the target dialect; and replacing each phoneme in the acoustic model with a modified phoneme, wherein the modified phoneme is a weighted sum of plausible phonemes in the lattice of plausible phonemes.
17. A computer-readable storage device having instructions stored which, when executed by a computing device, cause the computing device to perform operations comprising: identifying an acoustic model, wherein the acoustic model is trained on native speech in a target dialect; transcribing collected speech from a speaker, to yield a lattice of plausible phonemes which depend on a property of the target dialect; and replacing each phoneme in the acoustic model with a modified phoneme, wherein the modified phoneme is a weighted sum of plausible phonemes in the lattice of plausible phonemes. 18. The computer-readable storage device of claim 17 , wherein upon replacing the each phoneme in the acoustic model, the acoustic model is a Gaussian mixture model.