12. An apparatus comprising: a processor; and a memory coupled to the processor and storing computer readable instructions, the memory and the instructions configured to, with the processor, cause the 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.
17. The apparatus of claim 12 , wherein the computer readable instructions for the generation of the adaptation sentence, when executed, cause the apparatus to: determine a plurality of candidate adaptation sentence phoneme distributions of a plurality of candidate adaptation sentences; identify a first candidate adaptation sentence of the plurality of candidate adaptation sentences that has a minimal cross entropy measure with the desired phoneme distribution; and select the first candidate adaptation sentence as the adaptation sentence.