Harnessing the Zero-Shot Power of Instruction-Tuned Large Language Model
  in End-to-End Speech Recognition
Yosuke Higuchi Tetsuji Ogawa Tetsunori Kobayashi
We present a novel integration of an instruction-tuned large language model
(LLM) and end-to-end automatic speech recognition (ASR). Modern LLMs can
perform a wide range of linguistic tasks within zero-shot learning when
provided with a precise instruction or a prompt to guide the text generation
process towards the desired task. We explore using this zero-shot capability of
LLMs to extract linguistic information that can contribute to improving ASR
performance. Specifically, we direct an LLM to correct grammatical errors in an
ASR hypothesis and harness the embedded linguistic knowledge to conduct
end-to-end ASR. The proposed model is built on the hybrid connectionist
temporal classification (CTC) and attention architecture, where an
instruction-tuned LLM (i.e., Llama2) is employed as a front-end of the decoder.
An ASR hypothesis, subject to correction, is obtained from the encoder via CTC
decoding, which is then fed into the LLM along with an instruction. The decoder
subsequently takes as input the LLM embeddings to perform sequence generation,
incorporating acoustic information from the encoder output. Experimental
results and analyses demonstrate that the proposed integration yields promising
performance improvements, and our approach largely benefits from LLM-based
rescoring.