arXiv cs.CL
7/8/2026

Revisiting the Relation Between Language Model Perplexity and ASR Word Error Rate for Modern End-to-End Speech Recognition
Short summary
This paper re-examines the historically linear log-log relationship between language model perplexity (PPL) and ASR word error rate (WER) in the context of modern end-to-end speech recognition systems. The authors investigate whether external LMs still improve current ASR systems, how encoder context length affects the PPL-WER relation, and how LLM perplexities fit existing trends. They also show that internal language model subtraction in attention-based encoder-decoder systems alters the observed PPL-WER relation, indicating the decoder's internal LM must be accounted for when evaluating external LM quality.
- •Revisits the PPL-WER linear relation assumption for modern end-to-end ASR systems
- •Examines impact of external LMs, encoder context length, and LLM perplexities on the trend
- •Shows internal LM subtraction changes the observed relation, complicating external LM quality interpretation
Generated with AI, which can make mistakes.
Is this a good recommendation for you?