scope:

This Recommendation specifies the service description and the requirements for speech-to-speech translation (S2ST) accomplished by connecting distributed S2ST modules all over the world through a network. This service provides S2ST that recognizes the speech in one language, translates the recognized speech into another language, and then synthesizes the translation into speech. People who speak different languages can communicate using this service.

The applications and services using network-based S2ST technologies are characterized by the following components:

- S2ST client:

• user client for speech/text input and output.

- S2ST servers:

• speech recognition: speech is recognized and transcribed;

• machine translation: text in source language is translated into text in target language;

• speech synthesis: speech signal is created from text.

- Communication protocol:

• communication protocol to connect user clients and the above S2ST servers.

In order to extend the network-based S2ST to other modalities (e.g., sign language), a communication protocol is incorporated for modality conversion (MC), which converts single/multiple modality information to different single/multiple modality information. The communication protocol for MC needs to have an expandable structure.

- Modality conversion markup language (MCML):

• XML schema that serves as a data description for data exchanged among modality conversion modules.