14. The specific call detecting method according to claim 13 , wherein the determining whether at least one of the first and second voices is to be a target of voice recognition or not, determines that the first voice is a target of voice recognition until a period in which the utterance ratio is higher than a predetermined threshold, reaches a first period, and determines that the first voice is not a target of voice recognition after the period in which the utterance ratio is higher than the threshold, reaches the first period.
14. The specific call detecting method according to claim 13 , wherein the determining whether at least one of the first and second voices is to be a target of voice recognition or not, determines that the first voice is a target of voice recognition until a period in which the utterance ratio is higher than a predetermined threshold, reaches a first period, and determines that the first voice is not a target of voice recognition after the period in which the utterance ratio is higher than the threshold, reaches the first period. 19. The specific call detecting method according to claim 14 , further comprising: determining unit whether a psychological state of the first speaker is normal or not on the basis of the first voice; wherein the detecting a keyword related to a specific call, detects a first keyword having the number of syllabic sounds equal to or larger than predetermined number of syllabic sounds from voice determined as a target of the voice recognition when it is determined that the psychological state of the first speaker is normal and, on the other hand, detects the first keyword and a second keyword having the number of syllabic sounds less than the predetermined number of syllabic sounds from voice determined as a target of the voice recognition when it is determined that the psychological state of the first speaker is not normal.