The Computer-Assisted Listening and Speaking Tutor (CALST) is a pronunciation training platform with listening, pronunciation, and spelling exercises. In the video to the right, we explain what the aim of the exercises is and how they work. The exercises are demonstrated for Norwegian, but the explanations are equally valid for all languages.

Several target languages have been implemented in CALST: (British) English, (European) Spanish, Italian, Greek, and Norwegian. For Norwegian, the learner can choose between several dialects because the language does not have an accepted pronunciation standard and its speakers will normally use their own dialect independently of the communicative setting. In collaboration with the University of Barcelona, we are currently creating language content for Catalan, which will be added before the summer of 2024.

CALST offers exercises for a basic vocabulary of 1000 words and expressions, but the main goal of the platform is not vocabulary learning. CALST helps you to learn speech sounds in the target language that you do not have in your native language and may find difficult. Sometimes, sounds are familiar but can only occur in specific positions (and are difficult to pronounce in positions where they cannot occur in the native language). For this reason, there are exercises for sounds at the beginning and at the end of the word (if possible in the target language, of course).

Not only can you learn new speech sounds in CALST, the platform also offers exercises for consonant clusters, word stress, and lexical tone – the latter only in Norwegian since the other target languages do not have lexical tones (lexical tones refer to the word melodies that can distinguish the meaning of words that consist of identical speech sounds). A further restriction is that lexical tone exercises have only been implemented in the Oslo dialect because of limited funding; note that the lexical tones can be realized differently in other Norwegian dialects.

CALST is made for migrants who want to learn the language spoken in their new host country as well as for foreign language learners in general.

Take me to CALST

  • Is pronunciation important?

Absolutely! We most often use a new language in conversations with others. A good pronunciation will make it easier for your conversation partner to understand you (comprehensibility) and will help you make a positive first impression and avoid prejudice, be it in social settings or in a job interview.

  • Pronunciation is a skill

Are you learning a new language, and do you want to work more on your pronunciation? Language courses often pay little attention to pronunciation because learning to recognize new sounds categories and developing the motor skills for new articulations requires repetition. Practice, practice, practice is best done outside of the classroom – as long as you remember to use what you have learnt in real conversations.

  • One size fits all?

Nope. Learners with different native languages meet different challenges. A speaker of Modern Standard Arabic may find it hard to pronounce the first sound in English pest (pronouncing it best), while a Chinese learner may find it hard to say zoo instead of Sue. CALST tailors the exercises to your native language, so that you can focus on what may be difficult for you. The comparison is made using L1-L2map and is based on sound phonetic knowledge. This is all done automatically, so you do not have to think about this.

  • One for all and all for one

There are still many unsolved questions in language learning. That is why your exercise results are logged and stored anonymously. By allowing this, you help to further tailor the exercises for other learners who speak the same native language as you. By registering to CALST, you become part of the language learning community and help to solve the puzzle of language learning.



Frequently asked questions

Frequently asked questions

CALST can be run from any pc, tablet or smartphone, irrespective of the operating system. CALST uses a responsive design, which means it automatically adapts to the screen size of your device.

Note that the browser is not allowed to access the microphone on an iPhone or iPad. On these devices, you will therefore only get listening and writing exercises, but no pronunciation exercises. We advise users to take these exercises on any other device (including an Apple laptop).

Yes, CALST is a web-based pronunciation training platform, so you need access to the internet to run CALST – but we do use local storage to deal with short interruptions of your internet connectivity. You can run CALST from most browsers, but it has been fully tested only with Chrome. You can download Chrome for free to your device.

Registered users can see the results from all the exercises they have taken. Also, CALST will remember the last exercise and automatically direct you to the next one.
By registering you allow your results to be logged, so that they can be used to improve CALST and to tailor the exercises for other learners with the same native language.

  1. The pronunciation learning typically starts with two listening exercises. In the first exercise you hear two very similar words, followed by a repetition of one of these words. By comparing the last word to the first two words in your acoustic memory and choosing one, you learn what distinguishes them. This is called a discrimination task.
  2. After the discrimination exercise you take another listening exercise in which you just hear one word. Your task is to say which of two very similar words it is. Since you cannot compare with any words you have just heard, this requires that you have a clear idea of their pronunciation (a so-called internal representation). This task is called an identification task.
  3. Once you have learned to hear the sounds (or other properties, like word stress) correctly, you are ready to pronounce them. By listening to a recording of your own voice and comparing it to the tutor’s, you can adapt and improve your pronunciation.
  4. Finally, it can be hard to know how words that you hear are written. Therefore, writing exercises help you to learn the relationship between sounds and letters in the language that you are learning.

If a speech sound does not occur in your language, you have to learn it. But even a sound that you have in your native language can be hard to pronounce. For example, some sounds may be easy to pronounce at the beginning of a word, but is not allowed at the end of a word in your native language: Chinese for instance allows only nasal consonants as in kin and king at the end of a syllable. So even though a Chinese has no problem with /p/ in pill, the same sound may be hard to pronounce at the end of the word lip. German and Dutch speakers will say /p/ and /s/ at the end of a syllable or word instead of /b/ and /z/, even though they allow both /b/ and /z/ at the beginning of a syllable/word. So even known sounds may be difficult in positions where they do not usually occur in your native language.

This is quite natural, actually. It is a result of the fact that your perception becomes more and more tuned to your native language in the first few months of life. This automatically also means that it becomes more and more difficult to distinguish categories in another language. If a new sound (category) is similar to a sound (category) in your native language, you will perceive it as the same, even if native speakers of the language you are learning can clearly and easily hear and pronounce the difference. This is called the “native language filter”. There are large individual differences, of course: Some people are better able to put the filter out of play than others.

Some languages allow very complex consonant clusters, like Polish. The word bezwzględny mean “ruthless” (quite appropriately for most leaners of Polish). Japanese, on the other hand, only allows syllables consisting of a single consonant followed by a vowel. Pronouncing unusual clusters can be hard, and we solve the problem by using different repair strategies: Language learners may simplify the clusters, substitute some sounds, add an e- at the beginning or insert a vowel into the cluster to break it up into two syllables; finally, we can reorder the consonants in the cluster. Since there is no knowing what learners may do (i.e., scientists cannot yet predict this on the basis of your native language), you get exercises for all repair strategies – until our logged user data are reliable enough to select only those exercises which deal with the repair strategy that other learners with the same native language use.

Prosody refers to properties of the language which are at a level higher than individual speech sounds. Word stress, lexical accents and intonation are prosodic properties. Since these are different across languages, CALST offers exercises for those. You can take the exercises several times, with different exercise material each time you take the exercises (except for the intonation exercises). This allows you to practise with new words as much as you like.
[Feature only available in Norwegian]
To answer your logical follow-up question “Why are there no exercises for prosody in English”: We are dependent on external funding for the implementation of exercises in English (and in other languages), which is hard to obtain. We hope to add these exercises in future, though.

In contrast to many other languages, Norwegian does not have a standard pronunciation. In their everyday use of the language, people speak their own dialect. Since these can be very different, you will have to learn to understand all of them when you learn Norwegian. So it is very useful to take the listening exercises for all the dialects in CALST. But you can choose one dialect which you want to learn to speak. This may be the dialect of the region where you are living, or often foreigners learn the Oslo dialect which is spoken by the largest group of Norwegians.

We are grateful for any questions and comments which help us to improve CALST. Please send an email to

logo CALST


CALST is becoming slow when it loads a new exercise. A new and fast implementation is under development. You can test it on, and you can send your feedback to

How do the exercises work?

How do the exercises work?

Project members

User feedback

This is an awesome project! Thanks for making it! =)

CALST diverse

The project makes use of several resources developed by others:

Sound inventories

Sound inventory data are based on the UCLA Phonetic Segment Inventory Database (UPSID). These data are used to select sound contrast exercises dependent on the learner’s native language. This is done in the tool L1-L2map which lies behind CALST. We gratefully acknowledge the support of Ian Maddieson.


Pictures to illustrate the semantic content are an important part of the CALST program. The criteria we used as guidelines for the creation and selection of pictures were: drawings rather than photographs, simple style, few details, clear contours, intuitive, unambiguous, neutral and universal, but reflecting a "Norwegian reality" where relevant.

About one third of the pictures were taken from the open-source database UVic created by the University of Victoria, British Columbia.

The remaining pictures were either drawn on the computer or drawn by hand and subsequently scanned and edited by Eli Skarpnes and Egil Albertsen.


Koreman, J., Bosoni, J.G., Abrahamsen, J. & Husby, O. (2016). L2 exercises for East-Norwegian word accents and intonation, Nordic Prosody XII, Trondheim (abstract).

Koreman, J., Albertsen, E., Martínez-Paricio, V., Husby, O. & Abrahamsen, J. (2016). Learning about word stress in L2 acquisition, New Sounds 2016, Aarhus (abstract).

Husby, O., Koreman, J., Albertsen, E. & Bosoni, J.G. (2016). Uttaleundervisning - progresjon, Den 7. nasjonale forskningskonferansen om norsk som andrespråk, Trondheim (abstract).


Koreman, J., Martínez-Paricio, V., Abrahamsen, J. & Husby, O. (2015). A systematic approach to the pronunciation training of phonotactics, Proc. 18th Int. Congress of Phonetic Sciences (ICPhS2015), Glasgow.

Koreman, J., Husby, O., Hedayatfar, K. & Bech, Ø (2015). Learning from L2 learners to improve CAPT, ICPhS satellite workshop Phonetic Learner Corpora (abstract).

Martinez-Paricio, V. Koreman, J. Husby, O., Abrahamsen, J. & Bech, Ø. (2015). Consonant clusters in online L2 teaching: a multilingual approach, Proc. of the Pronunciation in Second Language Learning and Teaching (PSLLT) conference, volume 6, 115-125.

Martinez-Paricio, V. Koreman, J. Husby, O. (2015). L1-L2map: una base de datos fónica para la enseñanza de la pronunciación de segundas lenguasPerspectivas actuales en el análisis fónico del habla. Tradición y avances en la fonética experimental, 241-248. Publicacions de la Universitat de Valencia.

Husby, O., Koreman, J., Martínez-Paricio, V., Abrahamsen, J., Albertsen, E., Hedayatfar, K. & Bech, Ø (2015). Selective teaching of L2 pronunciation, in: Citical CALL. Proc. of the 2015 EUROCALL Conference, 243-248, Padova (abstract).

Koreman, J., Husby, O., Martínez-Paricio, V. & Abrahamsen, J. (2015). L1-L2map: una base de datos fónica para la enseñanza de la prononciación de segundas lenguas, in: A.C. Nebot (ed.), Perspectivas actuales en el análisis fónico del habla: tradición y avances en la fonética experimental, Departamento de Filología Española.


Koreman, J., Husby, O., Martínez-Paricio, V. & Abrahamsen, J. (2014). Individuali­sering av læringsstien i norsk som andrespråk: lytte- og uttaletrening, Den 6. Nasjona­le Forskerkonferansen om Norsk som Andrespråk: Hvor Går Andrespråksforskningen?,Stavanger, Norway (abstract).

Martínez-Paricio, V., Koreman, J., Husby, O. (2014). CALST: Una herramienta digital para la enseñanza de la pronunciación de segundas lenguas, XV Congreso Internacio­nal de la Sociedad Española de Didáctica de la Lengua y la Literatura (SEDLL),Valencia, Spain (abstract).

Martínez-Paricio, V., Koreman, J., Husby, O., Abrahamsen, J.E. & Bech, Ø. (2014). Expanding CALST: multilingual analysis of L1-L2 phonotactics for language teachingPronunciation in Second Language Learning and Teaching (PSLLT 2014), Santa barbara, USA.

Web Content Display






Koreman, J., Husby, O., Albertsen, E., Wik, P., Øvregaard, Å., Nefzaoui, S., Skarpnes, E. & Bech, Ø. (2013). Dealing with language diversity in teaching foreigners Norwegian pronunciationTromsø International Conference on Language Diversity, Tromsø (abstract).

Koreman, J., Husby, O., Albertsen, E., Wik, P., Øvregaard, Å., Nefzaoui, S., Skarpnes, E. & Bech, Ø. (2013). L1 variation in foreign language teaching: challenges and solutionsFifth Annual Conference on Pronunciation in Second Language Learning and Teaching, Ames, Iowa. (abstract).

Koreman, J., Wik, P., Husby, O. & Albertsen, E. (2013). Universal contrastive analysis as a learning principle in CAPTProc. of the workshop on Speech and Language Technology in Education (SLaTE 2013), ISSN 2311-4975, pp. 172-177.

Koreman, J. & Marinova, R. (2013). Språkteigen 17.02.2013, NRK P2 [Radio].


Haugan, I. (2012). Treningsstudio for språkopplæring. Gemini 4, p. 6 (article in Nynorsk).

Koreman, J., Husby, O. & Wik, P. (2012). Comparing sound inventories for CAPT, in: O. Engwall (ed.), Proc. International Symposium on the Automatic Detection of Errors in Pronunciation Training (IS-ADEPT), 115-116. Stockholm: KTH, Computer Science and Communication (abstract).


Husby, O., Øvregaard, Å., Wik, P., Bech, Ø., Albertsen, E., Nefzaoui, S., Skarpnes, E. & Koreman, J. (2011). Dealing with L1 background and L2 dialects in Norwegian CAPT, Proc. of the workshop on Speech and Language Technology in Education (SLaTE2011), Venice (Italy).

Koreman, J., Bech, Ø., Husby, O. & Wik, P. (2011). L1-L2map: a tool for multi-lingual contrastive analysis, Proc. 17th Int. Congress of Phonetic Sciences (ICPhS2011), Hong Kong.

Wik, Pr. Husby, O., Øvregaard, Å., Bech, Ø., Albertsen, E., Nefzaoui, S., Skarpnes, E. & Koreman, J. (2011). Contrastive analysis through L1-L2map. TRITA-TMH 2011, vol 51.

Øvregaard, Å. (2011). Språkteigen 19.06.2011, NRK P2 [Radio].

Øvregaard, Å. (2011). Språkteigen 27.11.2011, NRK P2 [Radio].


Koreman, J. & Øvregaard, Å. (2010). Computer-Assisted Listening and Speaking Tutor, Høstseminar Norgesuniversitet 2010, Tromsø.

Koreman, J., Øvregaard, Å., Albertsen, E., Nefzaoui, S. & Skarpnes, E. (2010). Computer-Assisted Listening and Speaking Tutor, Individuell lytte- og uttaletrening med virtuell lærer. Nasjonal konferanse om bruk av IKT i utdanning og læring (NKUL 2010), Trondheim.

Øvregaard, Å. (2010). CALST (Computer-Assisted Listening and Speaking Tutor). NOAkonferansen, Voss.

Øvregaard, Å. (2010). CALST (Computer-Assisted Listening and Speaking Tutor). Hitech Lotech 2010.


Koreman, J., Husby, O., Nefzaoui, S., Skarpnes, E., Øvregaard, Å. (2009). Computer-assisted Norwegian Teaching for Foreigners, Mutual Information Talks in ISK (MITISK), Institutt for språk og kommunikasjonsstudier NTNU, Trondheim.

2009: The CALST project started on 1 August 2009. The project was based on the Virtual Language Teacher (VILLE) an engine developed for Swedish by Preben Wik during his Ph.D. (see thesis) at the Division of Speech, Music and Hearing at KTH, Stockholm. Preben Wik was involved in the start of the project as part of the «think tank» and technical developer.

2013: The first version of CALST was launched by NTNU, Trondheim, on January 1. It was a downloadable version of the platform and contained vocabulary exercises for Norwegian and exercises for learning difficult Norwegian sounds based on the learner’s native language.

2015: The first web-based version appeared on January 1.

In April, a collaborative project to develop English contents was funded by the University of Agder (Allison Wetterlin, with Jacques Koreman).

A proposal for a Ph.D. project in NTNU’s Enabling Technologies initiative was granted. The doctoral candidate will apply feature-based automatic speech recognition (ASR) to automatic pronunciation evaluation. The proposal was written by Torbjørn Svendsen (IET) and Jacques Koreman (ISL). The project results can be used for automatic pronunciation evaluation in CALST.

On 1 July 2015, the exercises were extended with sound cluster exercises and a user logging was made implemented.

2017: In June 2017, the spin-off company Sounds Good was founded.

In October 2017, a new version of CALST, with a more user-friendly user interface, was launched.

The total budget for the CALST project is well around 15 million Norwegian krones.

The first CALST project was supported financially by Norway Opening Universities (Norgesuniversitetet) for the period from August 2009-August 2012. Final evaluation of the project

NTNU, Faculty of Humanities as well as the Department of Language and Communication Studies have also contributed to the project, among other things by financing L1-L2map.

The webification of CALST and large parts of the following development of the platform were funded by VOX.

NTNU has contributed with financial support to the development of exercises for lexical tone and intonation.

Several ministries, amongst others Kommunal- og regionaldepartementet (KRD), Barne- og likestillingsdepartmentet (BLD) and Arbeidsdepartementet (AD), have funded further research in the CALST project through VOX, which is now a part of the Norwegian Directorate for Higher Education and Skills.

Spanish, Italian and Greek versions of CALST are being developed in the easyRights project (Horizon 2020 SC6-MIGRATION project number 870980, January 2020 – June 2023, see

In 2023, NTNU Discovery supported the project with a pilot project (“forprosjekt”, project number 2023-38, subproject 998012171)  in which CALST was implemented using a new programming environment with a fast server response.


Thanks for providing this great resource! I will be excited to use the new version.

Jeg skal jobbe som lærer for syriske flyktninger fra høsten, og lurer på om det er mulig å få tilgang til CALST? Konseptet ser svært lovende ut, håper det passer for barn også.

Et supert opplegg!

Først, tusen takk for programmet ditt. Jeg lærte mye norsk når jeg fortsatt bodde i England ved å lese artikler og se på NRK (med undertekst), men det var CALST som hjalp meg utrolig mye med lytteforståelse. Jeg flyttet hit i september og besto Bergenstesten i oktober, og jeg kunne ikke ha gjort det uten dere.

Jeg jobber nå som engelsklærer og lurte på om dere visste om det var noe tilsvarende for engelsk. Det var ekstremt nyttig for meg i norsk, og jeg vet at elevene mine ville få den samme nytten av det.

This is an awesome project! Thanks for making it! =)

Your feedback encourages us to continue to improve CALST! Suggestions for improvements to are also welcome.