WER-BERT: Automatic WER Estimation with BERT in a Balanced Ordinal Classification Paradigm

Akshay Krishna Sheshadri, Anvesh Rao Vijjini, Sukhdeep Kharbanda


Abstract
Automatic Speech Recognition (ASR) systems are evaluated using Word Error Rate (WER), which is calculated by comparing the number of errors between the ground truth and the transcription of the ASR system. This calculation, however, requires manual transcription of the speech signal to obtain the ground truth. Since transcribing audio signals is a costly process, Automatic WER Evaluation (e-WER) methods have been developed to automatically predict the WER of a speech system by only relying on the transcription and the speech signal features. While WER is a continuous variable, previous works have shown that positing e-WER as a classification problem is more effective than regression. However, while converting to a classification setting, these approaches suffer from heavy class imbalance. In this paper, we propose a new balanced paradigm for e-WER in a classification setting. Within this paradigm, we also propose WER-BERT, a BERT based architecture with speech features for e-WER. Furthermore, we introduce a distance loss function to tackle the ordinal nature of e-WER classification. The proposed approach and paradigm are evaluated on the Librispeech dataset and a commercial (black box) ASR system, Google Cloud’s Speech-to-Text API. The results and experiments demonstrate that WER-BERT establishes a new state-of-the-art in automatic WER estimation.
Anthology ID:
2021.eacl-main.320
Volume:
Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume
Month:
April
Year:
2021
Address:
Online
Editors:
Paola Merlo, Jorg Tiedemann, Reut Tsarfaty
Venue:
EACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
3661–3672
Language:
URL:
https://aclanthology.org/2021.eacl-main.320
DOI:
10.18653/v1/2021.eacl-main.320
Bibkey:
Cite (ACL):
Akshay Krishna Sheshadri, Anvesh Rao Vijjini, and Sukhdeep Kharbanda. 2021. WER-BERT: Automatic WER Estimation with BERT in a Balanced Ordinal Classification Paradigm. In Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume, pages 3661–3672, Online. Association for Computational Linguistics.
Cite (Informal):
WER-BERT: Automatic WER Estimation with BERT in a Balanced Ordinal Classification Paradigm (Sheshadri et al., EACL 2021)
Copy Citation:
PDF:
https://aclanthology.org/2021.eacl-main.320.pdf
Data
CoLAGLUELibriSpeech