Fine-Tuning Whisper

Whisper is a pretrained encoder-decoder model for speech tasks. Fine-tuning continues training on paired audio and text so the model can better handle a target distribution, vocabulary, or language condition. It does not mean simply adding a dictionary: the model weights are updated using examples, and the resulting behavior depends on the data, objective, and training setup. Start with carefully aligned audio-transcript pairs. Transcripts should match the spoken content and use consistent conventions for punctuation, casing, numbers, disfluencies, and non-speech events. Audio should be decoded and sampled as expected by the model processor. Remove duplicates and check that segments are neither truncated nor mismatched. A small number of label errors can misdirect learning, particularly in a small adaptation set. Split by speaker, source, or session before training so related utterances do not appear in both training and evaluation. Keep a validation set for checkpoint and hyperparameter decisions and a separate test set for final reporting. Word error rate is common for ASR, but normalization choices affect it; report them. Evaluate different accents, noise conditions, and target vocabulary, not just an overall average. Large models require more memory and compute and may be harder to fine-tune on limited hardware. Smaller checkpoints can be practical, but model size alone does not determine quality. Parameter-efficient methods such as low-rank adapters can reduce trainable parameters when supported by the chosen tooling, yet their behavior and compatibility must be verified. Compare with prompt or decoding adjustments and retrieval of domain terms before committing to training. Fine-tuning may improve a target domain while reducing performance elsewhere, especially if adaptation data are narrow. Monitor both target and general validation sets when broad capability matters. Save the base model reference, processor, training configuration, dataset version, and final checkpoint so the result can be reproduced and audited.