CorAIt – A Non-native Speech Database for Italian
Authors: Claudia Roberta Combei (Università di Pisa, 2017)
Topic: Multimodal

Abstract
CorAIt is a non-native speech database for Italian, which is freely accessible online for academic research purposes. It was especially designed to meet the requirements of a larger research project focused on foreign accented Italian speech. The corpus is aimed at providing a uniform collection of speech samples uttered by non-native speakers of Italian. To date, 105 non-native speakers – whose mother tongues are either French, Romanian, Spanish, English, German, or Russian – have been recorded. The corpus includes also a control group made up of 16 Italian speakers. There are almost 8 hours of audio material, both read speech (first and second reading), and spontaneous speech. This paper emphasizes the necessity for this type of database, it describes the steps involved in its construction, and it presents the features of CorAIt.

Introduction
It has become clear that accurately designed speech corpora are of essential importance for the development of efficient speech technologies. Investigating how native and foreign-accented speech differ is a necessary step in non-native speech recognition AUTHOR. Currently, the number of non-native speech databases seems almost insignificant if compared to corpora of native speech. Moreover, until recently, the majority of the research has focused on English. Therefore, some of the largest non-native speech databases are available for this language: TED AUTHOR, Duke-Arslan AUTHOR, ISLE AUTHOR, IBM-Fisher AUTHOR, ATR-Gruhn AUTHOR, CSLU AUTHOR, NATO M-ATC AUTHOR, and Speech Accent Archive AUTHOR. Large speech corpora of foreign-accented English are owned by Speechocean, and they are specifically built for commercial purposes, especially for training and testing speech recognizers, but some of them are also available for academic research on the KilingLine Data Center platform AUTHOR. Only in the last few years has there been an interest in other languages. Without claiming to be exhaustive, some of the largest non-native speech databases for languages other than English will be mentioned: BAS Strange I+II AUTHOR for German, WP Russian AUTHOR for Russian, Tokyo-Kikuko AUTHOR for Japanese, TC-STAR AUTHOR and WP Spanish AUTHOR for Spanish, SINOD AUTHOR for Slovenian, and iCALL AUTHOR for Chinese. However, as a result of that fact that many nonnative speech databases are built for commercial purposes within private research centres, it is actually quite difficult to map all the resources of this type ever built (Cf. AUTHOR, for an overview of the non-native speech databases available at the date their study was published). This paper presents CorAIt, a non-native speech database for Italian. The database is part of a Ph.D. project which intends to study foreign accented Italian speech both from a computational perspective (automatic identification and classification of non-native accent) and a perceptual perspective (interpretation of quantitative and qualitative judgments delivered by expert and naïve native Italian speakers with respect to non-native pronunciations). The design and the development of this corpus were determined by several factors, which are outlined below.

Conclusion
Considering that currently this non-native speech database presents some imbalance issues as regards the speakers’ age of Italian language onset, their proficiency level, as well as the length of their residence in Italy, the data collection will be further extended. In the future, the web database might also be enhanced with orthographic and phonetic transcriptions. Disfluencies (i.e. false starts, filled and silent pauses, phoneme lengthening, mispronounced words), mouth clicks, and external noise could be annotated.