Instituto de Telecomunicações at IWSLT 2025: Aligning Small-Scale Speech and Language Models for Speech-to-Text Learning

This paper presents Instituto de Telecomunicaes's submission to the IWSLT 2025 Shared Task on Instruction Following Speech Processing.We submit results for the Short Track, i.e., speech recognition, translation, and spoken question answering.Our model is a unified speech-to-text model that integrates a pretrained continuous speech encoder and text decoder through a first phase of modality alignment and a second phase of instruction finetuning.Crucially, we focus on using smallscale language model backbones (< 2B) and restrict to high-quality, CC-BY data along with synthetic data generation to supplement existing resources. 1