Abstract: The language is composed using phonemes which is easy to separate in an environment of noise and disturbing sound.An acoustic signal comprising phonemes which is easy to separate in an environment of noise and disturbing sound fed to the acoustic signal analyzer is analyzed therein, and from the result of the analysis, the tone name is recognized in the tone name identifier, and after the tone name is recognized as a prescribed sentence, the sentence is fed to the utterance generator. Corresponding to these operations, the utterance generator generates a prescribed time series composed of tone names comprising phonemes which is easy to separate in an environment of noise and disturbing sound, and inputs it to the acoustic signal generator. The acoustic signal generator synthesizes an acoustic signal which corresponds to the time series and outputs the acoustic signal.