3. The specific call detecting device according to claim 1 , wherein the voice recognition execution determining unit determines that the second voice is not a target of voice recognition until a period in which the utterance ratio is equal to or less than a predetermined threshold, reaches a second period, and determines that the second voice is a target of voice recognition after the period in which the utterance ratio is equal to or less than the threshold, reaches the second period.
3. The specific call detecting device according to claim 1 , wherein the voice recognition execution determining unit determines that the second voice is not a target of voice recognition until a period in which the utterance ratio is equal to or less than a predetermined threshold, reaches a second period, and determines that the second voice is a target of voice recognition after the period in which the utterance ratio is equal to or less than the threshold, reaches the second period. 6. The specific call detecting device according to claim 3 , further comprising a psychological state determining unit which determines whether a psychological state of the first speaker is normal or not on the basis of the first voice, wherein the voice recognition execution determining unit sets the second period when it is determined that the psychological state of the first speaker is not normal to be shorter than the second period when it is determined that the psychological state of the first speaker is normal.