Speak & Improve Corpus 2025: an L2 English Speech Corpus for Language Assessment and Feedback

TL;DR

The Speak & Improve Corpus 2025 is a comprehensive, annotated dataset of L2 English speech designed to advance language assessment and feedback technologies, addressing data scarcity in this domain.

Contribution

This paper introduces a large, publicly available L2 English speech corpus with detailed annotations, supporting research in proficiency assessment, error correction, and low-resource speech recognition.

Findings

Provides 315 hours of annotated L2 English speech data

Enables development of automatic proficiency assessment tools

Supports research in grammatical error detection and speech recognition

Abstract

We introduce the Speak & Improve Corpus 2025, a dataset of L2 learner English data with holistic scores and language error annotation, collected from open (spontaneous) speaking tests on the Speak & Improve learning platform. The aim of the corpus release is to address a major challenge to developing L2 spoken language processing systems, the lack of publicly available data with high-quality annotations. It is being made available for non-commercial use on the ELiT website. In designing this corpus we have sought to make it cover a wide-range of speaker attributes, from their L1 to their speaking ability, as well as providing manual annotations. This enables a range of language-learning tasks to be examined, such as assessing speaking proficiency or providing feedback on grammatical errors in a learner's speech. Additionally the data supports research into the underlying technology required for these tasks including automatic speech recognition (ASR) of low resource L2 learner English, disfluency detection or spoken grammatical error correction (GEC). The corpus consists of around 315 hours of L2 English learners audio with holistic scores, and a subset of audio annotated with transcriptions and error labels.