21. One or more non-transitory computer readable media storing computer-executable instructions which, when executed by a processor, cause an apparatus at least to: determine a phoneme distribution of a text corpus; determine an acoustic model gain distribution of phonemes of an acoustic model before and after adaptation of the acoustic model; determine a desired phoneme distribution based on the phoneme distribution and the acoustic model gain distribution; generate an adaptation sentence based on the desired phoneme distribution; and generate a prompt requesting a user speak the adaptation sentence.
21. One or more non-transitory computer readable media storing computer-executable instructions which, when executed by a processor, cause an apparatus at least to: determine a phoneme distribution of a text corpus; determine an acoustic model gain distribution of phonemes of an acoustic model before and after adaptation of the acoustic model; determine a desired phoneme distribution based on the phoneme distribution and the acoustic model gain distribution; generate an adaptation sentence based on the desired phoneme distribution; and generate a prompt requesting a user speak the adaptation sentence. 29. The one or more computer readable media of claim 21 , storing further computer-executable instructions which, when executed, cause the apparatus to apply a finite state grammar to provide structure to the adaptation sentence.