The Norwegian Parliamentary Speech Corpus

Proceedings of the 13th Conference on Language Resources and Evaluation (LREC 2022), pages 1003–1008 Marseille, 20-25 June 2022 © European Language Resources Association (ELRA), licensed under CC-BY-NC-4.0 1003 The Norwegian Parliamentary Speech Corpus Per Erik Solberg, Pablo Ortiz National Library of Norway, Telenor Research Oslo, Norway per.solberg@nb.no, pablo.ortiz@telenor.com Abstract The Norwegian Parliamentary Speech Corpus (NPSC) is a speech dataset with recordings of meetings from Stortinget, the Norwegian parliament. It is the first, publicly available dataset containing unscripted, Norwegian speech designed for training of automatic speech recognition (ASR) systems. The recordings are manually transcribed and annotated with language codes and speakers, and there are detailed metadata about the speakers. The transcriptions exist in both normalized and non-normalized form, and non-standardized words are explicitly marked and annotated with standardized equivalents. To test the usefulness of this dataset, we have compared an ASR system trained on the NPSC with a baseline system trained on only manuscript-read speech. These systems were tested on an independent dataset containing spontaneous, dialectal speech. The NPSC-trained system performed significantly better, with a 22.9% relative improvement in word error rate (WER). Moreover, training on the NPSC is shown to have a “democratizing” effect in terms of dialects, as improvements are generally larger for dialects with higher WER from the baseline system. Keywords: Corpus, Less-Resourced Languages, Speech Recognition, Speech Resource, Validation of LRs 1. Introduction The Norwegian Parliamentary Speech Corpus (NPSC) is an open dataset intended for acoustic modelling of Norwegian unscripted speech (The National Library of Norway, 2021). It is developed and distributed by the Language Bank at the National Library of Norway. The dataset consists of about 140 hours1 of recordings of meetings at Stortinget, the Norwegian parliament, in 2017 and 2018 with orthographic transcriptions in Nor- wegian Bokm˚al and Norwegian Nynorsk, the two offi- cial written standards of the Norwegian language. The dataset is public domain (CC0), and there are, conse- quently, no restrictions on its use. While there exist some open, datasets with manuscript- read speech for Norwegian Bokm˚al, there are few, un- scripted datasets suited for acoustic modelling of Nor- wegian. There is a lack of available speech data of both kinds for Norwegian Nynorsk. The NPSC is intended to fill this gap. In the remainder of this section, we show why a dataset like the NPSC is needed and list some existing datasets for Norwegian ASR. In section 2, we explain what the NPSC dataset contains. Section 3 lays out how the NPSC was developed. Section 4 reports on an ASR experiment where we have used the NPSC for training and testing. Finally, section 5 raises some points for discussion and suggests some avenues for further de- velopment, and section 6 concludes the paper. 1.1. Why Norwegian ASR is challenging Norwegian is the native language of most of Norway’s 5.3 million inhabitants. Even though the linguistic community is relatively small, the language is quite 1Including breaks. The speech amounts to about 126 hours. diverse, which makes ASR particularly challenging. Firstly, Norwegian has many dialects, …

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