Parameter-efficient Fine-tuning of Speaker-Aware Dynamic Prompts for Speaker Verification

Prompt tuning can effectively reduce tunable parameters in pretrained Transformers. However, it is weak at capturing speaker traits because the prompts can easily overfit the adaptation utterances, resulting in poor generalization to unseen speakers. This paper introduces a prompt pool comprising learnable prompts to tackle this issue. Unlike the traditional method that learns a fixed set of prompts for each training utterance, our method uses a dynamic selection strategy to select the best matching prompts in a pool for tuning, resulting in each prompt being tuned by its closely matched speaker. The objective is to make the prompts in the pool form speaker clusters, enhancing speaker prediction in the downstream classifier while maintaining the plasticity of the pre-trained Transformers. Our experiments on language mismatch in speaker verification demonstrate that the dynamic prompt pool provides a memory- and computation-efficient solution to fine-tune pre-trained Transformers.