  In this study, we experimented to examine the effect of adding the most
frequent n phoneme bigrams to the basic vocabulary on the German phoneme
recognition model using the text-to-phoneme data augmentation strategy. As a
result, compared to the baseline model, the vowel30 model and the const20 model
showed an increased BLEU score of more than 1 point, and the total30 model
showed a significant decrease in the BLEU score of more than 20 points, showing
that the phoneme bigrams could have a positive or negative effect on the model
performance. In addition, we identified the types of errors that the models
repeatedly showed through error analysis.
