@inproceedings{karita-etal-2023-lenient,
    title = "Lenient Evaluation of {J}apanese Speech Recognition: Modeling Naturally Occurring Spelling Inconsistency",
    author = "Karita, Shigeki  and
      Sproat, Richard  and
      Ishikawa, Haruko",
    editor = "Gorman, Kyle  and
      Sproat, Richard  and
      Roark, Brian",
    booktitle = "Proceedings of the Workshop on Computation and Written Language (CAWL 2023)",
    month = jul,
    year = "2023",
    address = "Toronto, Canada",
    publisher = "Association for Computational Linguistics",
    url = "https://aclanthology.org/2023.cawl-1.8",
    doi = "10.18653/v1/2023.cawl-1.8",
    pages = "61--70",
    abstract = "Word error rate (WER) and character error rate (CER) are standard metrics in Speech Recognition (ASR), but one problem has always been alternative spellings: If one{'}s system transcribes adviser whereas the ground truth has advisor, this will count as an error even though the two spellings really represent the same word. Japanese is notorious for {``}lacking orthography{''}: most words can be spelled in multiple ways, presenting a problem for accurate ASR evaluation. In this paper we propose a new lenient evaluation metric as a more defensible CER measure for Japanese ASR. We create a lattice of plausible respellings of the reference transcription, using a combination of lexical resources, a Japanese text-processing system, and a neural machine translation model for reconstructing kanji from hiragana or katakana. In a manual evaluation, raters rated 95.4{\%} of the proposed spelling variants as plausible. ASR results show that our method, which does not penalize the system for choosing a valid alternate spelling of a word, affords a 2.4{\%}{--}3.1{\%} absolute reduction in CER depending on the task.",
}

Word error rate (WER) and character error rate (CER) are standard metrics in Speech Recognition (ASR), but one problem has always been alternative spellings: If one{'}s system transcribes adviser whereas the ground truth has advisor, this will count as an error even though the two spellings really represent the same word. Japanese is notorious for {``}lacking orthography{''}: most words can be spelled in multiple ways, presenting a problem for accurate ASR evaluation. In this paper we propose a new lenient evaluation metric as a more defensible CER measure for Japanese ASR. We create a lattice of plausible respellings of the reference transcription, using a combination of lexical resources, a Japanese text-processing system, and a neural machine translation model for reconstructing kanji from hiragana or katakana. In a manual evaluation, raters rated 95.4{\%} of the proposed spelling variants as plausible. ASR results show that our method, which does not penalize the system for choosing a valid alternate spelling of a word, affords a 2.4{\%}{--}3.1{\%} absolute reduction in CER depending on the task.
Karita, Shigeki Sproat, Richard Ishikawa, Haruko
Lenient Evaluation of Japanese Speech Recognition: Modeling Naturally Occurring Spelling Inconsistency