8. A multi-lingual speech synthesizer for processing a multi-lingual text message in a mixture of a first language and a second language into a multi-lingual voice message, the synthesizer comprising: a storage device configured to store a first language model database having a plurality of first language phoneme labels and first language cognate connection tone information, and a second language model database having a plurality of second language phoneme labels and second language cognate connection tone information; a broadcasting device configured to broadcast the multi-lingual voice message; a processor, connected to the storage device and the broadcasting device, configured to: separate the multi-lingual text message into at least one first language section and at least one second language section; convert the at least one first language section into at least one first language phoneme label and converting the at least one second language section into at least one second language phoneme label; look up the first language model database using the at least one first language phoneme label thereby obtaining at least one first language phoneme label sequence, and look up the second language database model using the at least one second language phoneme label thereby obtaining at least one second language phoneme label sequence; assemble the at least one first language phoneme label sequence and at least one second language phoneme label sequence into a multi-lingual phoneme label sequence according to an order of words in the multi-lingual text message; divide the multi-lingual phoneme label sequence into a plurality of first pronunciation units, each of the plurality of first pronunciation units is in a single language and includes consecutive phoneme labels of a corresponding one of the at least one first language phoneme label sequence and the at least one second language phoneme label sequence; for each of the first pronunciation units, determine whether a number of available candidates for a corresponding one of the first pronunciation units in a corresponding one of the first language model database and the second language model database is equal to or more than a predetermined number corresponding to the one of the first pronunciation units; when the number of available candidates for each of the first pronunciation units in the corresponding one of the first language model database and the second language model database is equal to or more than the corresponding predetermined number, calculate a join cost of each candidate path, wherein each candidate path passes through one of the available candidates of each of the first pronunciation units; determine a connecting path between every two immediately adjacent first pronunciation units based on the join cost of each candidate path; produce inter-lingual connection tone information at a boundary between every two immediately adjacent phoneme label sequences; combine the multi-lingual phoneme label sequence, the first language cognate connection tone information at a boundary between every two immediately adjacent phoneme label of the at least one first language phoneme label sequence, the second language cognate connection tone information at a boundary between every two immediately adjacent phoneme labels of the at least one second language phoneme label sequence, and inter-lingual connection tone information to obtain the multi-lingual voice message, and output the multi-lingual voice message to the broadcasting device.
8. A multi-lingual speech synthesizer for processing a multi-lingual text message in a mixture of a first language and a second language into a multi-lingual voice message, the synthesizer comprising: a storage device configured to store a first language model database having a plurality of first language phoneme labels and first language cognate connection tone information, and a second language model database having a plurality of second language phoneme labels and second language cognate connection tone information; a broadcasting device configured to broadcast the multi-lingual voice message; a processor, connected to the storage device and the broadcasting device, configured to: separate the multi-lingual text message into at least one first language section and at least one second language section; convert the at least one first language section into at least one first language phoneme label and converting the at least one second language section into at least one second language phoneme label; look up the first language model database using the at least one first language phoneme label thereby obtaining at least one first language phoneme label sequence, and look up the second language database model using the at least one second language phoneme label thereby obtaining at least one second language phoneme label sequence; assemble the at least one first language phoneme label sequence and at least one second language phoneme label sequence into a multi-lingual phoneme label sequence according to an order of words in the multi-lingual text message; divide the multi-lingual phoneme label sequence into a plurality of first pronunciation units, each of the plurality of first pronunciation units is in a single language and includes consecutive phoneme labels of a corresponding one of the at least one first language phoneme label sequence and the at least one second language phoneme label sequence; for each of the first pronunciation units, determine whether a number of available candidates for a corresponding one of the first pronunciation units in a corresponding one of the first language model database and the second language model database is equal to or more than a predetermined number corresponding to the one of the first pronunciation units; when the number of available candidates for each of the first pronunciation units in the corresponding one of the first language model database and the second language model database is equal to or more than the corresponding predetermined number, calculate a join cost of each candidate path, wherein each candidate path passes through one of the available candidates of each of the first pronunciation units; determine a connecting path between every two immediately adjacent first pronunciation units based on the join cost of each candidate path; produce inter-lingual connection tone information at a boundary between every two immediately adjacent phoneme label sequences; combine the multi-lingual phoneme label sequence, the first language cognate connection tone information at a boundary between every two immediately adjacent phoneme label of the at least one first language phoneme label sequence, the second language cognate connection tone information at a boundary between every two immediately adjacent phoneme labels of the at least one second language phoneme label sequence, and inter-lingual connection tone information to obtain the multi-lingual voice message, and output the multi-lingual voice message to the broadcasting device. 10. The multi-lingual speech synthesizer of claim 8 , wherein each of the first language model database and the second language model database further includes audio frequency data of one or a combination of phrases, words, characters, syllables or phonemes that are formed by consecutive phoneme labels, and the one or the combination of phrases, words, characters, syllables or phonemes that are formed by consecutive phoneme labels is an individual pronunciation unit.