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In this paper we present the Arabic related natural language processing components of our German–Arabic speech-to-speech translation system which is being deployed in the context of interpretation during psychiatric, diagnostic interviews. For this purpose we have built a pipelined speech-to-speech translation system consisting of automatic speech recognition, machine translation, text post-processing, and speech synthesis systems. We have implemented two pipelines, from German to Arabic and vice versa, to conduct interpreted two-way dialogues between psychiatrists and potential patients. All systems in our pipeline have been realized as all-neural end-to-end systems, using different architectures suitable for the different components. The speech recognition systems use an encoder/decoder + attention architecture, the machine translation system is based on the Transformer architecture, the post-processing for Arabic employs a sequence-tagger for diacritization, and for the speech synthesis systems we use Tacotron 2 for generating spectrograms and WaveGlow as a vocoder. The speech translation is deployed in a server-based speech translation application that implements a turn-based translation between a German-speaking psychiatrist administrating the Mini-International Neuropsychiatric Interview (M.I.N.I.) and an Arabic speaking person answering the interview. As this is a very specific domain, in addition to the linguistic challenges posed by translating between Arabic and German, we also focus in this paper on the methods we implemented for adapting our speech to speech translation system to the domain of this psychiatric interview

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Proceedings of the Fifth Arabic Natural Language Processing Workshop, pages 1–11Barcelona, Spain (Online), December 12, 20201German-Arabic Speech-to-Speech Translation for Psychiatric DiagnosisJuan Hussain, Mohammed Mediani, †Moritz Behr, Sebastian StükerKIT - Karlsruhe Institute of Technologyfirstname.lastname@kit.edu†uceul@student.kit.eduM. Amin CheraguiUniversity of Adrarm cheragui@yahoo.frAlexander WaibelCarnegie Mellon Universityalexander.waibel@cmu.eduAbstractIn this paper we present the Arabic related natural language processing components of ourGerman–Arabic speech-to-speech translation system which is being deployed in the context ofinterpretation during psychiatric, diagnostic interviews. For this purpose we have built a pipe-lined speech-to-speech translation system consisting of automatic speech recognition, machinetranslation, text post-processing, and speech synthesis systems. We have implemented two pipe-lines, from German to Arabic and vice versa, to conduct interpreted two-way dialogues betweenpsychiatrists and potential patients. All systems in our pipeline have been realized as all-neuralend-to-end systems, using different architectures suitable for the different components. Thespeech recognition systems use an encoder/decoder + attention architecture, the machine trans-lation system is based on the Transformer architecture, the post-processing for Arabic employsa sequence-tagger for diacritization, and for the speech synthesis systems we use Tacotron 2 forgenerating spectrograms and WaveGlow as a vocoder. The speech translation is deployed in aserver-based speech translation application that implements a turn-based translation between aGerman-speaking psychiatrist administrating the Mini-International Neuropsychiatric Interview(M.I.N.I.) and an Arabic speaking person answering the interview. As this is a very specific do-main, in addition to the linguistic challenges posed by translating between Arabic and German,we also focus in this paper on the methods we implemented for adapting our speech to speechtranslation system to the domain of this psychiatric interview.1 IntroductionIn psychiatry the Mini-International Neuropsychiatric Interview (M.I.N.I.) is a short structured diagnosticinterview for psychiatric disorders (Sheehan et al., 1998). In Germany it is, among others, used for diag-nosing Arabic speaking refugees. Here, the language barrier is an obvious one, that is normally overcomewith the help of human interpreters. However, human interpreters are scarce, expensive and very oftennot readily available when an urgent diagnosis is needed. In the project Removing language barriers intreating refugees—RELATER we are therefore building a speech-to-speech translation (S2ST) system forinterpreting between a German speaking psychiatrist and an Arabic speaker taking the M.I.N.I. interview.The natural language processing (NLP) technology for this scenario faces two challenges: a) thegeneral linguistic challenges when translating between German and Arabic and b) the specific domain ofthe interview for which only very little adaptation data is available.In this paper, we describe the Arabic related NLP components with which we implemented the speechto speech translation between German and Arabic for the interview. These components are part of aserver-based application, where the client application is capable of running on mobile platforms; whereasthe components themselves run on remote powerful computation servers. The application realizes a turn-based interpretation system between the psychiatrist and the potential patient.While end-to-end S2ST translation systems are the latest trend in research, for our system we optedfor pipe-lined systems, because a) pipe-lined systems still outperform end-to-end systems (Ansari et al.,This work is licensed under a Creative Commons Attribution 4.0 International License. License details: http://creativecommons.org/licenses/by/4.0/.22020), and b) to the best of our knowledge no suitable corpus for training German–Arabic end-to-endS2ST systems exists, for any domain.All systems in our pipeline have been realized as all-neural end-to-end systems, using different archi-tectures suitable for the different components. The speech recognition system uses an encoder/decoder+ attention architecture (Nguyen et al., 2020b), the text segmentation component, and the machine trans-lation are based on the Transformer architecture (Vaswani et al., 2017a), and for the speech synthesis weuse Tacotron 21 (Shen et al., 2018) for generating spectrograms and WaveGlow as vocoder (Prenger etal., 2019).The rest of the paper is structured as follows: Section 2 describes the Arabic speech recognition systemin the pipeline, while section 3 describes the machine translation component and section 4 the Arabicspeech synthesis system. As the the topic of diacritization is very prominent for Arabic NLP, we discussthe specific issues we faced in our S2ST system in section 5. In section 6, we study the real-time aspectof our pipeline system which is essential for the deployment.2 Automatic Speech RecognitionFor Automatic Speech Recognition (ASR), we employ an LSTM-based sequence to sequence (S2S)model with encoder/decoder + attention architecture. This model yields better performance compared tothe self-attention S2S model with a comparable parameter size. Before the LSTM layers in the encoder,we place a two-layer Convolutional Neural Network (CNN) with 32 channels and a time stride of twoto down-sample the input spectrogram by a factor of four. In the decoder, we adopt two layers of uni-directional LSTMs and the approach of Scaled Dot-Product (SDP) Attention to generate context vectorsfrom the hidden states. More details about the models can be found in (Nguyen et al., 2020b). In section2.1, we list the data used for the training, testing, and domain adaptation. For the latter, we use primarymethods described in section 2.2. We report some implementation details and experimental results insection 2.3.2.1 DataWe use the following data sets. For each data set we give a short name and the duration in hour (h) or inminutes (m):• Alj.1200h: We use this set for the training or bootstrapping of our model. It consists of 1200hours of broadcast videos recorded during 2005–2015 from the Aljazeera Arabic TV channel asdescribed in (Ali et al., 2016). As reported, 70% of this set is in Modern Standard Arabic (MSA)and the rest is Dialectal Arabic (DA), such as Egyptian (EGY), Gulf (GLF), Levantine (LEV),and North African (NOR). The categories of the speech range from conversation (63%), interview(19%), to report (18%).• Alj.MSA+dialect.10h: A test set of 10 hours described in (Ali et al., 2016) as well. It in-cludes non-overlapped speech from Aljazeera, which was prepared according to (Ali et al., 2016)for an Arabic multi-dialect broadcast media recognition challenge. We use the set as it is withoutnormalizing Alif, Hamza or any other characters.• Alj.MSA.2h: This is a subset from Alj.MSA+dialect.10h where we cut only MSA utter-ances free from dialects from the beginning of the set until we reached the duration of 2 hours.• mini.que.ans.3.34h: This dataset consists of 915 utterances and 3.34 hours of readingM.I.N.I questions (Sheehan et al., 1998) and free answers from two speakers. We transcribed theanswers with our ASR system and then corrected them manually with our desktop application DaC-ToR (Hussain et al., 2020) which we used to correct the automatic transcription. For the recordingwe employed our online application TEQST2 which allows the user to read texts and record withtheir own mobile devices.1https://github.com/NVIDIA/tacotron22https://github.com/TEQST/TEQST3• mini-ans.42m: A test set that has been processed similarly to mini.que.ans.3.34h. Itconsists of 224 free answers on M.I.N.I questions with a duration of 42 minutes by one speaker.• mini.ques.50m: 225 M.I.N.I questions by the same speaker as from mini-ans.42m with aduration of 50 minutes.2.2 Domain Adaptation for ASRAs we will see in section 2.3, we obtain extremely poor performance on our target domain (psychiatricinterview). Therefore, we are investigating many approaches to adapt our speech recognition system tothe target domain. In this paper, we report about two experiments: the mixed-fine-tuning and the fine-tuning experiment (Chu et al., 2017). For mixed-fine-tuning, we begin with the pre-trained model onAlj.1200h data as a baseline and mixed-fine-tune it on the data resulting from mixing Alj.1200hwith the domain data mini.que.ans.3.34h. For mixed-fine-tune or fine-tuning the decoder, wefreeze the encoder, and train only the decoder. For fine-tuning, we don’t mix the data. Instead we useonly mini.que.ans.3.34h set. For mixed-fine-tuning and fine-tuning, We use the learning rates(0.0009) and (0.00001) respectively. We report the result in section 2.3.2.3 Experimental ResultsWe experimented with the LSTM-based encoder-decoder + attention using 40 log-Mel features, two-layer Convolutional Neural Network (CNN) with 32 channels, 6 encoder-layers, 2 decoder-layers. Fordata augmentation, we use dynamic time stretching and specAugument as described in (Nguyen et al.,2020b).For the output, we employed a sub-word tokenization method, byte-pair encoding (BPE) (Sennrich etal., 2015), (Gage, 1994). Empirical experiments indicated that 4k tokens yielded the best performance.The tokenizer is trained on MSA texts since we aim to have a well-performing system on MSA. Forthis reason, we obtain on the first test set MSA+dialect.10h, which contains dialect besides MSA, WordError Rate (WER) of 18.8% (see Table 1). While, On the second test set MSA.2h with only MSA data,we reach a WER of 12.6%. We employ the beam-search algorithm for the output sequence prediction,where the beam-size of 4 yields the best WER. This low beam-size is considered very efficient for thereal-time capability of the system.For Domain adaption, the results of the main model on both test sets mini-ans.42m andmini.ques.50m of the target domain have a very high WER: 40% and 30.4% respectively. Ourspeech recognition model is S2S without an additional language model scoring or a dictionary. Thedecoder learns the language model from the training data directly. The out-of-vocabulary (OOV) ratebetween the test sets and the training data Alj.1200h is 3%. Hence, The main reason of the highWER is not the OOV but the domain mismatch since the training data is from broadcast videos and thedomain of both test sets is psychiatric interviews. The results in the next section gives evidence for thishypothesis, since tuning only the decoder yields a considerable improvement.By mixed-fine-tuning the whole model with the same architecture, we reach an improvement on bothdomains, where the WER is reduced by 0.7% on both Alj.MSA+dialect.10h and Alj.MSA.2h.Besides, on mini-ans.42m and mini.ques.50m we obtain a WER reduction of about 22%. Bymixed-fine-tuning only the encoder we obtain comparable results. On the other hand, although fine-tuning the decoder only causes the forgetting of the out-of-domain (i.e. Alj.MSA+dialect.10hand Alj.MSA+dialect.10h) by increasing their WER by about 8%, it improves the in-domain (i.e.mini.ques.50m) to 6.2%. This is likely due to the questions being identical in the training and testset, however by different speakers. The reason of forgetting is that the fine-tuning does not use the wholetraining but only the in-domain data.3 Machine TranslationIt is a known fact that translating between structurally or morphologically different languages is a verydifficult task. Two well-known examples of these hard language pairs are English–German and English–Arabic. In this work, we are associating the worst of these two worlds: Arabic and German. An example4test set baseline mixed-FT Dec mixed-FT Dec FTAlj.MSA+dialect.10h 18.8 18.1 18.6 25.7Alj.MSA.2h 12.6 11.8 12.3 20.5mini-ans.42m 40.0 16.4 18.4 14.8mini.ques.50m 30.4 8.6 10.3 6.2Table 1: ASR results, where FT stands for fine-tuning and dec for Decoder. The values are the WordError Rate (WER) ↓ in percentof the unmistakable differences between these two languages is that both of them are morphologicallyrich: Arabic is highly inflectional ((Farghaly and Shaalan, 2009)) and German possesses word com-pounding. At the syntactic level, word order is a substantial difference between the two languages.Arabic is much more flexible in this respect.In this work, we face two major challenges: data scarcity caused by the understudied language pair andthe specificity of the domain of application. Indeed, the language pair under consideration here has beenout of the focus of the international machine translation campaigns. Such campaigns (such as WMT3and IWSLT4) are organized on a yearly basis, and have boosted considerably both the performance andthe available resources for the language pairs they consider. The data scarcity problem becomes evenmore severe when we know that the resulting system is to be involved in the communication betweenpsychiatrists and their patients. The genre of the language used therein is quite different from that usedin the news. This latter makes most of the available training data.In the following, we explain the steps we followed to overcome these limitations and to producea reasonable translation system. Then, we show the developed systems in action through empiricalevaluations.3.1 DataAlthough the language pair under consideration is not commonly studied, a reasonable training set couldbe gathered, thanks to the different data sources publicly exposed on the Internet. In Part A of Table 2,we give a summary about the exploited data sets and some of their important attributes.The TED corpus6 is our first source of data. This corpus is collected by (Cettolo et al., 2012) from thetranslations generated by volunteers for the TED talks, over the course of several years. By looking at thedata, we think that TED is cleaner and more suitable for speech translation. Therefore, we always startby a baseline trained on TED data only, and then we gradually introduce more data from other sources.Another extremely important source is the OPUS7 repository. OPUS is a large depot where paralleldata is collected from different sources and sometimes also preprocessed for a very large number oflanguage pairs. It turned out that not all of the data available in this repository is in a good shape.Therefore, we manually examined those corresponding to our language pair, and discarded those ofwhich we were convinced that they include very large amounts of noise. A good example of this noisydata is the OpenSubtitle corpus. After this manual filtering, the corpora used from OPUS are:Multi UN, News Commentary, Global Voices, and Tatoeba.The Wikipedia corpus is generated from German–English and Arabic–English corpora by pivot-ing over their English side. Although OPUS repository offers these two corpora for download, it doesnot offer the direct version Arabic–German. We use strict string matching of the English sides to findthe Arabic–German translations (i.e. Finding sentence pairs from the two corpora where the Englishsentences are exactly equal in both pairs).The QED corpus is a multilingual corpus for the educational domain produced by QCRI in Qatar3http://www.statmt.org/wmt20/4http://iwslt.org/doku.php5In-domain data6https://wit3.fbk.eu/7http://opus.nlpl.eu/5Corpus Sent. Pairs (×103) Words (×106) Vocab (×103)Ar De Ar DeA: Training DataTED 199 2.800 3.200 278.0 214.0Multi UN 165 4.700 4.800 165.0 121.0News Commentary 208.783 7.565 6.396 226.779 228.481Wikipedia 9.833 0.146 0.142 33.308 32.448QED 18.537 0.124 0.146 24.796 20.184JW300 358.501 5.805 5.479 215.926 255.981GlobalVoices 9 0.150 0.170 43.0 35.0Tatoeba 1 0.004 0.003 2.2 1.9Q+A-TRAIN5 0.257 0.004 0.005 1.899 1.657Total 954.408 21.383 20.348 - -B: Test DataTED-TEST 1.717 0.021 0.025 8.572 6.897JW-TEST 1.974 0.031 0.029 10.455 9.245Q+A-TEST5 0.129 0.002 0.002 1.209 1.060Table 2: Summary of the translation data sets(Abdelali et al., 2014). Similar to TED talks, this corpus consists of the transcription and translation ofeducational lectures. In this work, we use the version 1.4 of this corpus.8Finally, the JW300 corpus was crawled from the Jehovah’s Witnesses website9 by (Agić and Vulić,2019). The contents are of religious nature and are available in a large number of language pairs. Thiscorpus is also made available on the OPUS repository. However, unlike the other corpora, this one comesunaligned on the sentence level. Consequently, we perform sentence alignment on the raw downloadeddata. The process was held by the hunalign10 tool. However, this tool requires a dictionary for thelanguage pair; we automatically created one from the other aligned corpora. We used the fast align11tool to align the corpora at the word level in two directions. Afterwards, We restricted our dictionary toword pairs appearing 5 times or more in the two directions.The last row in Part A of Table 2 shows a part of our in-domain data. The other small part is used fortesting (Last row, Q+A-TEST in Part B of the same Table). This consists of the translations of the M.I.N.Iquestions. Added to them are manual translations of the transcribed answers by some patients. Theselatter correspond to the mini.que.ans.3.34h data set (mentioned in speech data stes in Section2.1).In addition to the training data, we use three test sets to evaluate the performance of our systems ondifferent kinds of data. Some details about these test sets are given in Part B of Table 2 (JW-TEST,TED-TEST, Q+A-TEST). The first two of these sets are considered as general domain and used tomeasure the model’s performance on out-of-domain tasks. While these two sets are both out-of-domainfor our purpose, they still represent different domains. The JW-TEST is a random subset drawn fromthe JW300, while ensuring that the test and the training sets remain disjoint. The TED-TEST set is thetest set used in IWSLT evaluation in 2012 (IWSLT2012). The last test set (Q+A-TEST), as mentioned inthe previous paragraph, consists of what was held out from the in-domain data to evaluate the system’sperformance on in-domain tasks. This latter test set, as well as its training counter-part (Q+A-TRAIN),is work in progress and will be extended in the future.8http://alt.qcri.org/resources/qedcorpus/9https://www.jw.org/en/10http://mokk.bme.hu/resources/hunalign/11https://github.com/clab/fast_align63.2 Domain Adaptation for Machine TranslationThe similarity between training and test data is a common assumption in machine learning (See e.g.(Daumé and Marcu, 2006) for an elaborate description of this issue). In most cases however, this as-sumption is violated in the field. This issue is usually resolved by performing in-domain adaptation.That is tweaking a model trained on large quantities of out-of-domain data using only the very fewavailable examples from the domain under consideration. As a result, the similarity between probabilitydistributions of the model and the domain is augmented.The tasks we perform in this work are no exception to the aforementioned problem. In order to adaptthe general system to the domain under consideration, some few in-domain examples are mandatory.In our work, these examples are the Q+A sets shown in the last rows of Parts A and B of Table 2. Itis noteworthy however, that these sets are being actively extended, since the manual data creation istime-consuming.So far, we explored two approaches to the adaptation: fine-tuning and data selection. Fine-tuning isaccomplished by resuming the training for very few additional epochs using only the in-domain data.Data selection provides us with more in-domain data. This is achieved by choosing a special subset oftraining examples from the general domain training set. This subset consists of general domain examples,which are the most similar to the in-domain examples. The selection process is carried out using (Mooreand Lewis, 2010) with more careful out-of-domain language model selection as proposed by (Medianiet al., 2014). The language models used in this procedure are 4-gram language models with Witten-Bellsmoothing. We perform the selection for both languages (i.e. once for Arabic and once for German).Then, we take the intersection of the two selected subsets.123.3 Experimental ResultsThe input data is preprocessed using the sentence piece13 algorithm. For Arabic the vocabularysize is set to 4000 and for German to 16000. Lines longer than 80 words are discarded. The model’sarchitecture is transformer encoder-decoder model (Vaswani et al., 2017b). Both the encoder and decoderare 8-layers. Each layer is of size 512. The inner size of the feed-forward network inside each layer is2048. The attention block consists of 8 heads. The dropout is set to 0.2. All trainings are run for 100epochs. While the number of epochs used for fine-tuning is taken to be 10. We use the Adam schedulingwith a learning rate initially set to 1 and with 2048 warming steps. The results are summarized in Table3.System JW-TEST TED-TEST Q+A-TESTA: German→ ArabicTED only 5.06 12.44 7.99TED+Extra data 23.90 14.62 8.19Fine-tuned 5.34 12.94 12.18Fine-tune-select 23.18 14.35 19.16B: Arabic→ GermanTED+Extra data 17.17 9.67 6.18Fine-tune-select 16.60 9.06 15.96Table 3: Summary of the translation experiments (results are expressed as BLEU (↑) scores)The scores in Table 3 are BLEU scores (Papineni et al., 2002). The table is subdivided into two panels,one for each translation direction. We report all tested combinations for the German→ Arabic direction.For the reverse direction we report results only for the most promising configurations. The configurationsshown here are as follows:12Other ways of combining selections from the two sides of the parallel corpus were not explored in this work. Our choice(i.e. the intersection) is motivated by our aim for higher precision.13https://github.com/google/sentencepiece7• TED only The training is performed on TED corpus only.• TED+Extra data the system is trained on all data.• Fine-tune The fine-tuning is done with the very small in-domain Q+A-train only.• Fine-tune-select where the fine-tuning is accomplished using the set consisting of the merge betweenQ+A-train and the 20K more sentences selected from the training corpora.As the table shows, using all the available data is helpful for all test sets. However, the JW-TEST is theone which benefits the most. This is to be expected as an important part from the training data comesfrom the JW300 corpus. That corpus was originally in the same set with JW-TEST. The fine tuning onthe tiny Q+A-train data set was not a good help to all test sets. While it introduces small improvementon the in-domain test, it was very harmful to the other sets. It causes the system to quickly overfit; mostlikely due to its small size and very restricted type of sentences. This is where the data selection comesin handy to fix these problems of the in-domain data set. This is demonstrated on the last row of thetwo panels of the table. The selection was able to bring a large improvement for the in-domain test set,without harming the other test sets from different domains.4 Speech SynthesisFor speech synthesis or Text-To-Speech (TTS), we use the state-of-the-art model, namely Tacotron 214(Shen et al., 2018) which is a recurrent S2S network with attention that predicts a sequence of Mel spec-trogram frames for a given text sequence. For generating time-domain waveform samples conditionedon the predicted Mel spectrogram frames, we chose WaveGlow (Prenger et al., 2019) where the authorsclaim that it has a faster inference than WaveNet (Oord et al., 2016) used with Tacotron 2 in (Shen et al.,2018).4.1 ExperimentsWe trained Tacotron 2 and used a pre-trained WaveGlow model found on the Github page of WaveGlow.We also kept most of the default parameters from the implementation except for the sampling rate wherewe use 16kHz for the audio. As input to the Tacotron 2, we used Arabic character sequences withdiacritics in Buckwalter format15.The corpus used for the training (Halabi, 2016) contains 1813 utterances with a duration of 3.8 hours.We first experimented with Arabic characters without diacritics to synthesize the audio directly from theMT output. Unfortunately, the model did not converge since even the same word in a different context isdiacritized differently. Employing BPE used for ASR (section 2) without diacritics did not work eithereven with pretraining with over 400 hours of the data set Alj.1200h. For this reason we developed thediacritization component (section 5) to our pipeline.The resulting speech sounds natural (see section 4.2), however, when synthesizing for only one word,the model does not terminate and reaches the maximum decoding steps. As a solution, we implementeddata augmentation by both splitting and merging utterances. We apply splitting on 708 out of the total1813 utterances which are in form of spoken separate words separated by silence, for instance:"ta>aa˜wSawa˜ra - wata>aa˜wSara - watu&a˜wSa - taSa>aa˜w"with an automatic approach. The algorithm simply finds positions with values under a threshold. Theseare simple to find since the corpus is recorded using a professional studio. Besides, we merge randomly2 and 3 utterances with the probabilities 0.2 and 0.1 respectively if the duration stays under 30 seconds.This approach solved the one words synthesizing. However, another issue appeared, the synthesis con-tained short silence where it is not supposed to. This is due to the silence between the concatenatedutterances which we solved by adding the symbol for silence ”-” used already in the corpus between toconcatenated utterances. It is worth to mention that this method solved an issue of the German synthesisfor long sentences.14The source code is available at https://github.com/NVIDIA/tacotron215Buckwalter transliteration can be found here: http://www.qamus.org/transliteration.htm84.2 ResultsFor the evaluation of the naturalness of the resulting speech, we constructed an online form including10 synthesized speech from the first 10 utterances of the test set Alj.MSA.2h (section 2.1) after dia-critizing them manually. Besides, we added 3 real speech samples from the training data to judge theseriousness of the evaluators and whether the task has been properly understood by the participants. Thescale we use is 1 if the speaker is a robot, 2 near to a robot sound, 3 no difference, 4 near to human sound,and 5 the sound is from a human. From the 18 participations we received, we deleted the whole evalu-ation of participants who evaluated one or more of the 3 real audio samples with 2 or below. It remains11 valid votes with an average of 4.05 as a Mean Of Opinion (MOP ↑). For the whole 18 participationswithout deleting any invalid votes we obtain a MOP of 3.82. This means that the synthesized speech isof very good quality, in most cases judged as very close to human speech.5 DiacritizationAs mentioned earlier (Section 4), the dicritization was introduced to make the TTS understandable. Wewere, indeed, unable to synthesize good Arabic speech without these short vowels. The synthesis, then,consists of incomprehensible mumbles as the system tends to insert the vowels arbitrarily.Diactritics have a crucial role in giving the Arabic text a phonetics (Abbad and Xiong, 2020). More-over, they allow for better comprehension by reducing the level of ambiguity inherent in the Arabictranscription system. Having that said, most modern written Arabic resources omit these diacritics andrely on the ability of the native speakers to guess them from the context. In particular, all the paralleldata used to train our translation systems has no diacritics.We employ a sequence-tagger trained using the Flair-framework (Akbik et al., 2018), which is aBiLSTM-CRF proposed by (Huang et al., 2015). besides (Akbik et al., 2018) introduces ContextualString Embeddings. Thereby, sentences are passed as sequences of characters into a character-level Lan-guage Model (LM) to form word-level embeddings. This is done by concatenating the output hiddenstate after the last character in the word from the forward LM and the output hidden state before theword’s first character from the backward LM. These two language models result from utilizing the hid-den states of the forward-backward recurrent neural network (see (Akbik et al., 2018) for more detailsabout the approach).5.1 DataFortunately, some available Arabic resources are diacritized. Al-Shamela corpus (Belinkov et al., 2016)is a large-scale, historical corpus of Arabic of about 1 billion words from diverse periods of time. It isimportant to specify that the corpus in its initial state will not be exploitable in our resolution process,for this reason, a series of operations will be carried out, as follows:• Delete empty lines and lines with a single character and keep only lines with a high amount ofvowels (> 40% of characters are short vowels)• Split words to obtain pairs consisting of (letter, Diacritic Mark).Applying these steps to the Al-Shamela corpus gives an amount of around 5 million lines of trainingdata. We used only a part of this large corpus (≈ 1.5 million lines). Some other parts of this corpus wereheld out for validation and testing (1300 validation set and 8000 lines for testing).5.2 ResultsWe use the sequence to sequence biLSTM provided by the Flair framework. We kept the configurationas simple as possible. The embeddings are obtained by stacking forward and backward embeddings ofsize 512 each. They were computed while training a one layer language model. The network consistsof an RNN encoder of 1 layer and 128 hidden states and a CRF decoder. With such a configuration, anaccuracy of 95.34% was achieved on the held out test set.96 Real-Time AspectsAll components of the pipeline reside on only one GPU of type TITAN RTX with 24 GB memory. Thenumber of components is 7 where there are 3 for each S2ST direction plus the diacritization componentfor Arabic side.We measured the latency of the system components by using 5 Arabic sentences from the test setAlj.MSA.2h consisting of 16, 9, 8, 12 and 9 words, hence 54 words in total. For ASR, we usethe synthesis of this sentences which has the total duration of 47.85 seconds. The ratio of the total du-ration of processing the 5 sentences by the whole pipeline system to the total input speech duration is7.9547.85 = 0.17. This means that the processing time is about 6 times faster than the input speech dura-tion. Hence, the system is real-time capable and Long sentences can be chunked into smaller parts in astream-like output (see (Nguyen et al., 2020a) as an example of using The LSTM-based model for ASRto process a stream). Table 4 shows the time duration in total for the 5 sentences, the average time persentence, per word, and the model size on the GPU.component total time avg. per sentence per word GPU model size (GB)ASR 1.06 0.212 0.020 1.4MT 1.90 0.381 0.035 0.9Diacritization 0.68 0.136 0.014 0.8TTS 4.31 0, 861 0.080 1.7Table 4: The measurement of the latency for each component of the pipeline. Times are in seconds(↓).The measurements are for 5 sentences with (16,9,8,12,9) words, i.e 54 words in totalIt can also be noted from the Table that the TTS is the slowest component in the pipeline.7 ConclusionIn this work, we presented the different components of our German–Arabic speech-to-speech translationsystem which is being deployed in the context of interpretation during psychiatric, diagnostic interviews.For this purpose, we have built a pipe-lined speech-to-speech translation system consisting of automaticspeech recognition, machine translation, text post-processing, and speech synthesis systems. We alsodescribed the problems we faced while building these components and how we proceeded to overcomethem.The speech recognition system uses an LSTM-based encoder/decoder + attention architecture, themachine translation component is based on the Transformer architecture, the post-processing for Arabicemploys a sequence-tagger for diacritization, and for the speech synthesis systems we use Tacotron 2 forgenerating spectrograms and WaveGlow as a vocoder.For domain adaptation, we used fine-tuning and mixed-fine-tuning on hand-created in-domain data.We achieved thereby considerable improvements despite the scarce collected domain data. This resultconfirms the already well established fact about the extreme importance of in-domain data. Therefore,collecting more of this domain-related data is on the top of our priorities in the near future. Certainly, thisdata collection process will not prevent us from trying more ways to exploit the data we already have.For instance, more efforts will be put into exploring other adaptation techniques. Additionally, we areinvestigating the exploitation of the large quantities of monolingual data in the translation components.AcknowledgementsThe work in this paper was funded by the German Ministry of Education and Science within the projectRemoving language barriers in treating refugees—RELATER, no. 01EF1803B.10ReferencesHamza Abbad and Shengwu Xiong. 2020. Multi-components system for automatic arabic diacritization. InEuropean Conference on Information Retrieval, pages 341–355. Springer.Ahmed Abdelali, Francisco Guzman, Hassan Sajjad, and Stephan Vogel. 2014. The amara corpus: Buildingparallel language resources for the educational domain. 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