27. The non-transitory medium of claim 21 , wherein the multiple types of sounds in the second language that cause pronunciation difficulties include: a first sound that does not contrast with a second sound in the language of the non-native speaker; and a third sound that does not exist in language of the non-native speaker.
27. The non-transitory medium of claim 21 , wherein the multiple types of sounds in the second language that cause pronunciation difficulties include: a first sound that does not contrast with a second sound in the language of the non-native speaker; and a third sound that does not exist in language of the non-native speaker. 28. The non-transitory medium of claim 27 , wherein the language of the non-native speaker is Japanese, the second language is English, the first sound is /r/, the second sound is /1/, and the third sound is /θ/.