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. 22. The one or more computer readable media of claim 21 , storing further computer-executable instructions which, when executed, cause the apparatus to adapt the acoustic model to generate an updated acoustic model based on updating statistical representations of the phonemes from speech input of the user speaking the adaptation sentence.