Before revision:  An external language model allows our approach to reach the quality of a comparable supervised setup and outperform a semi-supervised setup (both on test-clean). We establish a state-of-the-art result for end-to-end ASR trained on LibriSpeech train-clean-100 set with WER 4.3\% on test-clean and 13.5\% on test-other.
After revision:  An external language model allows our approach to reach the quality of a comparable supervised setup and outperform a semi-supervised setup for LibriSpeech test-clean and only 33\% worse than a comparable supervised setup. Our system establishes a competitive result for end-to-end ASR trained on LibriSpeech train-clean-100 set with WER 4.3\% on test-clean and 13.5\% on test-other.