**5. Conclusions**

In this work, we developed a 3D avatar-based sign language learning system that converts the English speech or text into corresponding ISL movements. Initially, the input speech is converted into an equivalent English sentence using the IBM-Watson service. The converted English text is further translated into the corresponding ISL sentence using regular expression and script generator. Finally, each word of the ISL sentence is transformed into an equivalent sign movement, represented by a 3D avatar. The translation method (English–ISL and ISL–sign movement) has been evaluated by the SER, BLEU, and NIST metrics. The proposed model achieved an 82.30% BLEU score that represents

the translation accuracy from English to ISL sentences. The text-to-sign translation model (from ISL sentence to sign movement) achieved a 10.50 SER score, which signifies that 89.50% of signs were correctly generated by the 3D avatar model for the respective ISL sentence. It may be noted that the proposed system has been developed for a limited corpus, and no facial expressions were included, which can be considered as an important part of any sign language system. The transition between the signs while performing a sign sentence can be improved further by learning specific transitions based on hand positions while signing. Moreover, the sign language recognition system that converts a sign to text/speech is significantly more difficult to develop. Such a system can be added within the proposed framework to build a complete sign language interpretation system.

**Author Contributions:** Conceptualization, D.D.C. and P.K.; methodology, D.D.C., P.K. and S.M.; software, S.M.; validation, D.D.C. and P.K.; formal analysis, D.D.C. and P.K.; investigation, P.P.R. and M.I.; data curation, D.D.C. and P.K.; writing—D.D.C., P.K.; writing—review and editing, P.P.R. and M.I.; visualization, M.I.; supervision, P.P.R. and B.-G.K.; project administration, B-G.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** No research funding has been received for this work.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
