IAES Inter national J our nal of Articial Intelligence (IJ-AI) V ol. 14, No. 2, April 2025, pp. 1605 ∼ 1615 ISSN: 2252-8938, DOI: 10.11591/ijai.v14.i2.pp1605-1615 ❒ 1605 Multi-task deep lear ning f or V ietnamese capitalization and punctuation r ecognition Phuong-Nhung Nguy en 1 , Thu-Hien Nguy en 2 , Nguy en T ruong Thang 1 , Nguy en Thi Thu Nga 1 , Nguy en Thi Anh Phuong 1 , T uan-Linh Nguy en 3 1 Institute of Information T echnology , V ietnam Academy of Science and T echnology , Hanoi, V ietnam 2 F aculty of Mathematics, Thai Nguyen Uni v ersity of Education, Thai Nguyen, V ietnam 3 F aculty of Electronics Engineering, Thai Nguyen Uni v ersity of T echnology , Thai Nguyen, V ietnam Article Inf o Article history: Recei v ed Feb 29, 2024 Re vised Oct 21, 2024 Accepted No v 14, 2024 K eyw ords: Capitalization Deep learning Multitask learning Named entity recognition Punctuation ABSTRA CT Speech recognition is the process of con v erting the speech signal of a particular language into a sequence of corresponding content w ords in te xt format. The output te xt of automatic speech recognition (ASR) systems often lacks struc- ture, such as punctuation, capitalization of the rst letter of a sentence, proper nouns, and names of l ocations. This absence of structure complicates compre- hension and restricts the utility of ASR-generated te xt in v a rious applications, such as creating mo vie subtitles, generating transcripts for online meetings , and e xtracting customer information. Therefore, de v eloping standardization solu- tions for the output te xt from ASR is necessary to impro v e the o v erall quality of ASR systems. In this article, we use the idea of multitask deep learning for the task of capitalization and punctuation recognition (CPR) for the output te xt of V ietnamese ASR, with the aim of the named entity recognition (NER) task as a supplement to help the CPR model perform better , and proposed to use te xt-to- speech (TTS) to create a dataset for CPR-NER multitask model training. The e xperiment results sho w that the multi-task deep learning model has impro v ed CPR results by 6.2% of F1 score with ASR output and 7.1% on ra w te xt. This is an open access article under the CC BY -SA license . Corresponding A uthor: T uan-Linh Nguyen F aculty of Electronics Engineering, Thai Nguyen Uni v ersity of T echnology Thai Nguyen, V ietnam Email: ntlinh@tnut.edu.vn 1. INTR ODUCTION Automatic speech recognition (ASR) refers to the v arious processes, technologies, and met h odol ogies that f acilitate impro v ed interaction between humans and computers by con v erting spok en language into written te xt [1], [2]. The output te xt of the ASR system, besides containing some i nsertion, deletion, and w ord substitution errors, often has no punctuation and no capitalization. The issue of standardizing te xt by rest o r ing punctuation and capitalization is necessary . It will mak e the te xt more structured and understand- able. Furthermore, it will f acilitate NLP tasks including named entity recognition (NER), syntactic parsing, part-of-speech tagging, and discourse se gmentation [3]. Additionally , it benets practical applications such as generating mo vie subtitles, broadcasting ne ws transcripts, creating documents for online meetings, and e xtract- ing customer information more ef fecti v ely [4]. Research in this eld has traditionally focused on indi vidual tasks, such as restoring punct uation [5]–[7] or capitalization [8]–[10]. Ho we v er , these separate processing techniques are challenging to impro v e J ournal homepage: http://ijai.iaescor e .com Evaluation Warning : The document was created with Spire.PDF for Python.
1606 ❒ ISSN: 2252-8938 the o v erall ef fecti v eness of the ASR systems. Therefore, recently , authors ha v e proposed models to simultane- ously handle tw o tasks [4], [11]–[13]. Initially , research in this eld utilized methods such as maximum entrop y [14], hidden mark o v model (HMM) [15], long short-term memory (LSTM) [16], and cond i tional random eld (CRF) [17], [18]. Currently , the most adv anced models for both punctuation restoration and capitalization recognition use neural netw ork models. St udies ha v e e xplored the character -le v el recurrent neural netw ork (RNN) model [19], bidirectional RNN [20], [21]. P articularly , with the emer gence of the transformer model and its v ariations lik e BER T , RoBER T a, ALBER T , DistilBER T , mBER T , and XLM-RoBER T a, studies on restoring punctuation and capitalization on the transformer model [12], [22], BER T [10], [23], RoBER T a [24], ha v e sho wn positi v e results. Moreo v er , research on the V ietnamese language has also follo wed this inno v ati v e and promising trend, using CRFs combined with CNNs and LSTM [25], transformer [26]–[28]. Notably , the V iBER T model, based on RoBER T a for V ietnamese, is the latest model that achie v es better performance in both tasks [29]. There are also ha v e some limitations and challenges that need t o be solv ed for the problem of re storing punctuation and capitalization in general and V ietnamese in particular . Re g arding data-related issues, to deal with lo w-resource language data, some studies ha v e e xperimented with us ing standardized te xt without punc- tuation and capitalization [3], [6], [26]. Because commas and periods appear more frequently than other marks, most research focuses only o n these marks [12], [30], [31]. ASR output te xt does not ha v e punctuation, so it is often long and endless. T o process such te xt in models, input sequences are usually randomly cut into ranges of 20-30 w ords [32] or 20-50 w ords [24], maximum length 100 w ords [33] and 150 w ords [25]. Determining the appropriate length for cutting is a matter that needs to be considered. The proposal to use o v erlap-chunking in cutting and concatenating sequences has helped impro v e the model [9]. The issue of mismatched sequence lengths due to errors lik e insertions, deletions, and substitutions in the ASR output te xt is one of the major challenges that need to be addressed. Determining the order of punctuation restoration and capitalization is still an important issue as it can signicantly impact the nal results [29]. Multi-task deep learning (MTDL) has g ai ned signicant attention in the eld of machine learning [34] and natural language processing (NLP) [35]. It has been used to address challenges such as o v ertting and data scarcity in NLP tasks. Dif ferent architectures, including parallel, hierarchical, modular , and generati v e adv ersarial architectures, ha v e been emplo yed for multi-task learning (MTL) in NLP . Optimization techniques such as loss construction, data sampling, and task scheduling ha v e been utilized to train multi-task models ef fecti v ely . MTL has sho wn promising results in v arious NLP tasks, including machine translation, dialogue- based systems, sentiment analysis, and machine reading comprehension. In this study , our goal is to propose a MTDL for simultaneous capitalization and punctuation recogni- tion (CPR). W e combine MTL with t he h ypothesis that inte grating a NER model will impro v e the performance of punctuation restoration and capitalization. Additionally , we also emplo y the o v erlap-chunking technique and the V iBER T language model, which ha v e sho wn ef fecti v eness in NER [13]. P articularly , to cope with lo w-resource language data, we consider using te xt-to-speech (TTS) to augment the training data. This paper is structured as follo ws: the initial session addresses the problem and re vie ws related research. The second session disc u s ses our proposed approach and the architecture of the MTDL CPR system. In the third session, the focus is on the dataset’ s implementat ion and preparation for both training and testing. Session four details the conguration steps for the testing process and presents the e v aluation outcomes. Lastly , the fth session of fers a conclusion and recommendations for future research a v enues. 2. METHOD 2.1. Multi-task deep lear ning f or capitalization and punctuation r ecognition Using the idea from MTL for the task of punctuation and capitalization restoration, a MTDL approach is proposed with the aim of impro ving the performance of the CPR task. Figure 1 illustrates the proposed MTDL model, which consists of the main CPR task combined with an auxiliary NER stream that pro vides additional information about the named entity (NE) for the punctuation and capitalization restoration task. The input data to the model is the output te xt of V ietnamese ASR without punctuati on and capitalization, with a length of N . During recognition, some sentences may contain errors such as substitutions, inserti ons, and deletions, making the punctuation and capitalization restoration task more challenging. The sentence from input is transferred through the V iBER T , a V ietnamese language representation model. In this study , a transfer learning approach is applied with V iBER T , a pre-trained model that is k ept x ed in the proposed MTDL model. Int J Artif Intell, V ol. 14, No. 2, April 2025: 1605–1615 Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Artif Intell ISSN: 2252-8938 ❒ 1607 The output of V iBER T is a matrix of size ( N x 768) . This representation matrix is simultaneously fed into three blocks: (i) the NER information e xtraction block, (ii) the main CPR restoration block, and (iii) the NER auxiliary learning block using a MTL mechanism. Figure 1. Proposed MTDL CPR model Figure 1 sho ws the proposed multitask deep learning model, which includes the main CPR stream and NER stream to support the NE information for CPR. Both CPR and NER tagger are based on the transformer decoder structure in [29]. The input data consisted of unpunctuated and uncapitalized V ietnamese sentences, which were e xtracted from the output of an ASR system, with a set size of N. The input sentence underwent processing using the representation of V ietnamese language m odel kno wn as V iBER T . This model produced an output in the form of a matrix, characterized by dimensions of (Nx768), which encode the repres entation of the input sentence. This matrix representation w as simultaneously directed to w ard three distinct components: (i) a block that e xtracts NE information, referred to as the NE encoder; (ii) the main CPR block; and (iii) an auxiliary block for NER. The supplemental block for e xtracting NER information incorporated a NER tagging block along with an NER embedding block, which functioned to encode recognizable NER tags. These encoded tags were meant to supply pertinent information to the CPR block. The CPR block represented the core task of the MTDL model and utilized output from the sentence’ s representation matrix produced by V iBER T . This input w as mer ged (concatenated) with the NER tag encoding matrix, emanating as the output from block (ii). This mer ger with the output from block (ii) enriched t he NER information, thereby enhancing the precision of the CPR labeling process. The output from the block w as a collection of probabilities corresponding to NER tags for the s p e cic input sentence, and the loss function for this process w as calculated based on these NER labels. The encoder block w as link ed to the NER embedding block through a mechanism that shared parameters, as illustrated in (1). W ithin this conguration, the weight matrix of the NER embedding w as replicated from the transposed matrix of the encoder in block (iii). W emb = W T enc (1) The netw ork w as trained using a MTL approach that in v olv ed tw o tasks: CPR, which serv ed as the primary task, and NER, which functioned as a supporti v e, auxiliary task. The loss v alue for the MTDL model Multi-task deep learning for V ietnamese capitalization and punctuation ... (Phuong-Nhung Nguyen) Evaluation Warning : The document was created with Spire.PDF for Python.
1608 ❒ ISSN: 2252-8938 w as determined by taking a weighted sum of the loss v alues from both the CPR and NER tasks. The MTDL model’ s loss v alue is computed as follo ws: the losses from the CPR and NER tasks are each assigned a weight, and then these weighted losses are summed toget her to yiel d the nal loss v alue for the model, as sho wn in (2). L mtl = α L CPR + β L NER (2) Where α is the weight for the loss v alue of the CPR task, and β is the weight for the loss v alue of the NER task. The choice of α and β depends on the importance of each task. In this study , the CPR task is considered the primary task and the NER task as the auxiliary task. Therefore, α and β are chosen to be 0.6 and 0.4, correspondently . 2.2. Input text o v erlap segmentation The input for the CPR model recei v es output te xt from ASR. This te xt typically lacks punctua- tion, resulting in a long, indenite sequence that poses considerable challenges for processing by models. Therefore, before being fed into the model, the input sequence is often se gmented into x ed-length portions, which enhances the ability to process independently or in parallel se gments. Related research particularly focuses on the se gmentation of the input sentence sequence and often emplo ys a strate gy of random cutting within a range of 20-30 w ords [32] or 20-50 w ords [24]. Ho we v er , this approach can lead to a lack of suf cient conte xtual information around the boundaries of the se gments, resulting in predictions that are often inaccurate. T o o v ercome this limitation, research has proposed a ne w technique for handling the cutting and concatenation of sequences by utilizing o v erlapping cuts. The main idea is to ensure that the resulting se gments ha v e enough conte xtual information for the w ords, enabling the CPR model to mak e the best predictions. After processing the o v erlapping se gments, the y are mer ged back into the output sequence of the original string. Figure 2 details this architecture, which includes three components: the di vision of o v erlapping se g- ments, the CPR model, and the mer ging of the o v erlapping se gments. It can be seen that the input sentence is di vided into three se gments , which are stack ed in an o v erlapping f ashion. After being processed by the CPR model, the se gments are recognized in the middle of the second se gment ha ving more surrounding conte xt, thus being tagged m ore accurately than the w ords at the cutting boundary se gments. Finally , these se gment s will be mer ged in an o v erlapping manner to form the restored sentence. Figure 2. Ov erlap chunk-mer ging of input te xt The chosen length for the se gment cuts is an e v en number of w ords. Let l represent the length of the se gment cut, and k is the length of the o v erlapping part, then we ha v e l = 2 k . Each input string S , containing Int J Artif Intell, V ol. 14, No. 2, April 2025: 1605–1615 Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Artif Intell ISSN: 2252-8938 ❒ 1609 n w ords denoted as w 1 , w 2 , ..., w n , will be di vided into n/l + ( n − k ) /l o v erlapping se gments. Here, the i th se gment cut is a substring of w ords w i − 1 k + 1 , . . . , w i +1 k . The study has e xamined v arious v alues for l and k , and these v alues ha v e been selected empirically to be appropriate. As the input sentence is di vided into o v erlapping se gments, the challenge in mer ging these se gments is to determine which w ords should be discarded and which should be retained in the mer ged portion of the nal sentence. Let c be the length of the se gment that will be either retained or discarded in the o v erlappi ng parts. F or simplicity in calculation, we tak e c = k / 2 . Observ ations indicate that the ending w ords of the rst o v erlapping se gment and the initial w ords of the second o v erlapping se gment (the w ords around the cutting point) lack substantial conte xt. Therefore, the algorithm will discard the c se gment at the end of the rst o v erlapping part and retain the c se gment in the second o v erlapping part. Consequently , the remaining w ords at the be ginning of the rst o v erlapping se gment are k ept, and the remaining w ords at the start of the second o v erlapping se gment are discarded. This ensures that t h e w ords retai ned in the o v erlapping sections, al w ays situated in the m iddle of se gments, will ha v e ample conte xt, aiding in more accurate restoration. The process of discarding and retaining portions of the o v erlapping se gments is repeated for subsequent o v erlapping se gments. The post-catenation mer ging process is described as (3). [[ w 1 , . . . w (2 k − c ) ] + n − 1 X i =2 [ w (( i − 1) k + c ) , . . . w ( ik + c ) ] + [ w ( n − 2 k + c ) , . . . w n ] (3) 2.3. Dataset pr eparation Numerous datasets for V ietnamese speech are no w accessible to the public, e xamples of which in- clude MICA VNSpeechCorpus [36], DEMEN567 [37], and V O V [38]. Despite these resources being reported, it should be noted that the y may not encompass audi o data that is both lar ge-scale and of high quality . Besides, the e xisting speech datasets are not annotated with punctuation, capitalization, nor NE labels, Therefore, it is necessary to construct a suf ciently lar ge dataset complete with labels for punctuation, capitalization, and NE in order to train the CPR model using a MTL approach. The dataset for NER tailored to the V ietnamese language w as de v eloped as part of the acti vities of the V ietnamese language and speech processing conference (VLSP). It comprises 32,000 instances in the training dataset with an additional 4,272 samples designated for testing. The dat aset focuses on e xtracting specic entities which include indi vidual names (PER), or g anizational names (ORG), and geographic locations (LOC). Detailed information about this dataset can be found in [39]. The ini- tial dataset w as in XML format, featuring entities that were hierarchically nested. The dataset w as transformed into the CoNLL format for NER, which simplies the process by only identifying the primary-le v el entities. In the initial stages of data preparation, we transformed all te xt to lo wercase and e xcised an y speci al characters and punctuation, wit h the e xception of commas, periods, and question marks. Subsequently , we structured the dataset with annotations as per the schema presented in T able 1, which is arranged into three columns. The rst column contains the lo wercase v ersion of the input sentences. The second column holds the labels for CPR, with eight labels. The third column contains the NER labels , with six labels. T ables 2 and 3 sho w the statistics of our dataset. T able 1. F ormat of dataset for MTDL training T e xt CPR label NER label minh U$ B-PER ph ´ uc U, I-PER con L$ O trai L$ O ˆ ong L$ O hai U$ B-PER long U$ I-PER l ` am L$ O o L$ O h ` a U$ B-LOC giang U. I-LOC Multi-task deep learning for V ietnamese capitalization and punctuation ... (Phuong-Nhung Nguyen) Evaluation Warning : The document was created with Spire.PDF for Python.
1610 ❒ ISSN: 2252-8938 T able 2. Dataset statistics of CPR tag T ag T rain De v T est L$ 760,182 38,885 189,058 L, 35,647 1,884 9,327 L. 29,917 1,531 6,596 L? 860 35 151 U$ 127,973 6,630 30,313 U, 10,644 572 2,607 U. 8,097 400 1,843 U? 75 3 21 T able 3. Dataset statistics of NER tag NER tag T rain De v T est B-LOC 15,871 841 2,002 B-ORG 8,627 383 2,152 B-PER 16,299 883 3,466 I-LOC 15,810 830 1,850 I-ORG 19,132 1,026 3,899 I-PER 11,621 644 3,077 O 886,035 45,333 223,470 An alternati v e method for data collection utilizing TTS systems has been outlined in Figure 3, which is suggested as a substitute for traditional recording techniques: − Phase 1: T ransform written te xt into audible speech with the use of a TTS tool TTS technology has been under e xploration in V ietnam for some time. Initially , VnSpeech w as recognized as the pioneering V ietnamese TTS system. The V ietSound system, which is a product of Ho Chi Minh City Uni v ersity of T echnology , follo wed suit. Y et, these early systems had setbacks, particularly in pro- ducing speech that sounded disconnected and unnatural. In recent times, more rob ust and widely implemented TTS systems ha v e emer ged. Notably , FPT .AI of fers a TTS service reno wned for its ef fecti v eness. Additionally , the V iettel’ s VTCC.AI system and Vbee’ s AI TTS system are among the po werful players in the eld. T elecom companies lik e MobiPhone ha v e also introduced their TTS solutions. Google has been pro viding a TTS tool that is celebrated for its nat ural-sounding v oice, positioning it as one of t h e top contenders in TTS softw are. Le v eraging DeepMind’ s speech synthesis e xpertise, Google has crafted a v oice quality that listeners may nd challenging to dif ferentiate from human speech. In our study , we utilized the dataset of VLSP 2018 along with Google’ s TTS system to con v ert te xt into speech for both training and v alidation purposes. Due to resource constraints, our focus w as restricted to recording audio for the test set within the dataset, which comprises 4,272 samples totaling approximately 242,000 w ords. The speech dataset w as generated by four indi viduals who read the te xt in v arious settings, resulting in o v er 26 hours of recorded audio. − Phase 2: Utilizing the ASR system for speech recognition F ollo wing the acquisition of the audio dataset from both TTS and recordings, the data underwent processing via an ASR system. F or this phase, the V ietnam articial intelligence solutions (V AIS) ASR system w as selected due to its superior performance in recognizing V ietnamese speech when compared to other systems such as those by FPT , V iettel, Zalo, and Google, as noted in [40]. Additionally , the V AIS ASR system w as pre viously utilized in research focused on identifying mark ers in V ietnamese speech processing using a Pi peline approach, as mentioned in [13]. T o maintain consistenc y for result comparison, we opted to continue with the V AIS system for our e xperimental frame w ork. − Phase 3: Ev aluation of ASR te xt from synthesized speech T able 4 presents the error rates for the TTS-ASR process and the recorded te xt through ASR (REC- ASR) method, assessed across 241,899 w ords from the dataset. The ndings sho wed only a minor discrepanc y in ASR accurac y when comparing tw o data collection methods, which w as deemed pro visionally acceptable. In order to amass a substantial v olume of training data, we sourced information from authoritati v e V ietnamese ne ws websites, including vne xpress.net, dantri.com.vn, and vietnamnet.vn. This content w as then processed using a speech synthesis system to generate the v oice data. W e emplo yed the recorded speech from the VLSP 2018 dataset, featuring four distinct speak ers, as our test set. Int J Artif Intell, V ol. 14, No. 2, April 2025: 1605–1615 Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Artif Intell ISSN: 2252-8938 ❒ 1611 The dataset of VLSP2018 is se gmented into training, de v elopment, and testing subsets. The training subset contains 30,280 V ietnamese sentences; the de v elopment subset includes 1,593 sentences; and the testing subset comprises 4,271 sentences, all formatted with uppercase letters and punctuation. The VLSP sentences were annotated for capitalization, punctuation, and NE recognition. F or creating the test subset’ s audio, four indi viduals recorded the test te xt of the subset. The V AIS ASR system (https://v ais.vn/en/speech-to-te xt-core/) w as utilized to con v ert the spok en w ords into te xt data for e v aluation purposes. F or the generation of synthe- sized audio data from the te xtual VLSP data, Google’ s TTS system w as utilized. Additionally , V AIS’ s ASR system w as emplo yed to transcribe the synthetic audio, producing a te xt dataset for training the MTDL model. Figure 3. Data preparation process T able 4. Analysis of ASR error rates (%) of synthesized and recorded speech Number (%) Outlier (%) Other (%) T otal (%) TTS-ASR 1.061 2.418 1.582 5.068 REC-ASR 1.427 2.371 2.228 6.032 2.4. Model setting The V iBER T model is a scaled-do wn v ersion of the R oB E R T a base , whi ch is enforced using the f airseq frame w ork. This streamlined model retains 4 encoder layers as its R oB E R T a base counterpart. The number of attention heads has been reduced from 12 in the original to 4 in V iBER T . Each training instance can accommodate up to 512 tok ens. The V iBER T model is trained using the Adam optimization algorithm with a batch size of 512. It has a peak learning rate set at 0.0003 and a w arm-up phase consisting of 3,000 updates. The o v erall number of updates during training reaches 800,000. This training process is performed on tw o Nvidia 2080T i GPUs, each with 12 GB of memory , and spans a duration of 5 weeks. The suggested MTL model features both a CPR tagger and an NE tagger , both congured i d e ntically . Each tagger utilizes a transformer decoder to e xtract te xt features. At the output, a CRF model is emplo yed to produce se v en distinct labels. These labels include the be ginning (B-X) and inside (I-X) tags for entities in the cate gories of or g anizations (ORG), persons (PER), and locations (LOC), as well as t he O tag, which denotes tok ens that do not correspond to an y NE. F or the output of CPR, the model will assign labels that include ’U’ to denote uppercase, ’L ’ for lo wercase, combine with l abels ’$’ (indicating the absence of punctuation); ’. ’ (period); ’, ’ (comma); ’?’ (question m ark) to add punctuation to the input w ord. Consequently , each w ord will be associated with one of the follo wing eight labels: ’U$’; ’L$’; ’U. ’; ’L. ’; ’U, ’; ’L, ’; ’U?’; ’L?’. 3. RESUL T AND DISCUSSION 3.1. Ev aluation metrics Our model’ s performance is assessed through precision, recall, and the F1-score metrics for both tasks as sho wn in (4) to (5). pr ecision = T P T P + F P (4) r ecal l = T P T P + F N (5) r ecal l = 2 ∗ pr ecision ∗ r ecal l pr ecision + r ecal l (6) Multi-task deep learning for V ietnamese capitalization and punctuation ... (Phuong-Nhung Nguyen) Evaluation Warning : The document was created with Spire.PDF for Python.
1612 ❒ ISSN: 2252-8938 where true positi v e (TP) denotes the number of punctuation and capitalization tags that were correctly identied by the model. F alse positi v e (FP) signies the number of punctuation and capitalization tags that were mistak- enly identied. On the other hand, f al se ne g ati v e (FN) refers to the number of punctuation and capitalization tags that the model f ail to recognize. 3.2. Experiment r esult T able 5 presents the performance of our MTDL model in comparison to the baseline models (without NER auxilary task) transformer decoder CRF . F or the single-task training, the state-of-the-art method in v olv es rening V iBER T pre-trained language model for tok en classication tasks by adding a CRF layer on top [29]. The result presents the F1 scores associated with v arious types of inputs and highlights the shortcomings of the ASR-generated te xt when contrasted with te xt that is not case-sensiti v e (the reference te xt without capitalization and punctuation information) while the CPR results decreased from 0.7818 to 0.6319. T able 5. Capitalization and punctuation recognition results Input type Single task Multi-task Uncased reference te xt 0.7818 0.8375 ASR output 0.7319 0.7780 The MTL approach outperforms the single-task learning by a signicant mar gin, as e videnced by the scores of 0.8375 and 0.7818, respecti v ely . This suggests that MTL is more ef fecti v e at generalizi ng from uncased reference te xt, potential ly due to its ability to capture and utilize shared representations from NER that are rele v ant to the input te xt. The high performance of 0.8375 for MTL in processing uncased refere nce te xt indicates rob ust feature e xtraction and learning, which can handle the absence of case information ef fecti v ely . This could be attrib uted to the multi-task frame w ork’ s potential to le v erage auxiliary information from NER task, impro ving the model’ s understanding of conte xt. The ndings further conrmed that inte grating the NER component enhances the performance of the CPR model processing ASR-generated te xt. The F1 score for the CPR model sa w a notable increase of approximately 6.2%, rising from 0.7319 t o 0.778, after adding the NE recognition model to the te xt of ASR output. Additionally , the NER model pro v ed to be highly v aluable, as it substantially raised the F1 score of the CPR model by 7.1% with unprocessed te xt, which in this case, lack ed capitalization and punctuation in the reference te xt. 3.3. Ablation study Our model’ s performance assessment re v eals the signicance of its indi vidual components in comparison to our optimal model, which incorporates V iBER T as the encoding layer alongside all components. T able 6 illustrates the essential role each com ponent plays in our multitask learning model’ s ef fecti v eness. System performance deteriorates upon alteration or omission of components. The complete model achie v ed an F1 score of 0.8375, b ut this score dropped to 0.8034 when we e xcluded the NER feature and relied solely on conte xtual embedding for the capitalization and punctuation prediction tasks. When we substituted the o v erlap-chunk-mer ging the input te xt with t he non-o v erlap-chunk-mer ging, the F1 scores for the capitaliza- tion prediction task and punctuation prediction task fell to 0.8182. The ndings indicate that the presence of o v erlapping w ords in the model supplies additional information for prediction, and our method of mer ging chunks is capable of appropriately selecting se gments from t he areas of o v erlap. The most substantial decline occurred when we replaced conte xtual embeddings with w ord embeddings (GloV e), resulting in a 0.16 decrease in F1 score. T able 6. Performance metrics with component modications Component Modication Precision Recall F1 Full None 0.8398 0.8352 0.8375 NER Remo v al 0.8114 0.7953 0.8034 (4.08 % ↓ ) Chunking Non o v erlap 0.8215 0.8149 0.8182 (2.29 % ↓ ) Embedding GloV e 0.6826 0.6720 0.6773 (19.12 % ↓ ) Int J Artif Intell, V ol. 14, No. 2, April 2025: 1605–1615 Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Artif Intell ISSN: 2252-8938 ❒ 1613 4. CONCLUSIONS In our research, we introduced the application of a NER model to enhance capitalization and punctuation reco v ery in V ietnamese speech processing with the MTL scheme. The e xperimental results pro- vided e vidence of the syner gy between these methodologies. W e also created and presented the inaugural speech dataset that establishes a foundation for future e xplorations i nto entity e xtraction from V ietnamese speech. Additionally , we highlighted the signicant benets of utilizing a pre-trained language model tailored for the V ietnamese language processing in CPR and NER multi-tasks, which set a ne w benchmark on the VLSP 2018 dataset. W e ha v e made this pre-trained model a v ailable to the research community to encourage further e xploration. This contrib ution is particularly v aluable for underrepresented languages such as V ietnamese. 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W ang, “ A surv e y of vietnamese automatic speech recognition, ” in 2021 9th Inter national Confer ence on Or ang e T ec hnolo gy (ICO T) , IEEE, 2021, pp. 1–4, doi: 10.1109/ICO T54518.2021.9680652. BIOGRAPHIES OF A UTHORS Phuong-Nhung Nguy en recei v ed the master de gree from the Uni v ersity of T echnology - Hanoi National Uni v ersity , majoring in information technology . Her resea rch interests include data mining, machine learning, soft computing, and fuzzy computing. She is currently a researcher at the Institute of Information T echnology , V ietnam Academy of Science and T echnology . She can be contacted at email: ntpnhung@ioit.ac.vn. Int J Artif Intell, V ol. 14, No. 2, April 2025: 1605–1615 Evaluation Warning : The document was created with Spire.PDF for Python.