8. A voice guidance device comprising: a storing unit that stores a plurality of stored voice data items for each of a plurality of voice guidance phrases, each of the plurality of voice data items for a specific voice guidance phrase including the specific voice guidance phrase at a different frequency; a voice producing unit that produces at least one produced voice data item for each of the plurality of voice guidance phrases from the plurality of stored voice data items using voice synthesis, wherein each of the plurality of stored voice data items and the at least one produced voice data item of a first voice guidance phrase of the plurality of voice guidance phrases has a different frequency; a voice mixing unit that mixes at least two voice data items from the first voice guidance phrase to thereby produce a first mixed voice data item of the first voice guidance phrase; a voice outputting unit that outputs and sounds only the first voice guidance phrase using a first mixed voice for the first voice guidance phrase based on the first mixed voice data item; a voice detecting unit that detects a response voice responding to the outputted first voice guidance phrase using the first mixed voice; and a voice measuring unit that measures a frequency with respect to the detected response voice; the voice mixing unit producing a second mixed voice data item by mixing at least two voice data items of a second voice guidance phrase of the plurality of voice guidance phrases, different than the first voice guidance phrase and different from the detected response, the second mixed voice data item having the characteristic of the frequency that is measured by the voice measuring unit with respect to the response voice detected after the first mixed voice was sounded; the voice outputting unit further outputting and sounding only the second voice guidance phrase using a second mixed voice based on the second mixed voice data item in response to the response voice, the second voice guidance phrase approximating the frequency that is measured by the voice measuring unit with respect to the response voice.
8. A voice guidance device comprising: a storing unit that stores a plurality of stored voice data items for each of a plurality of voice guidance phrases, each of the plurality of voice data items for a specific voice guidance phrase including the specific voice guidance phrase at a different frequency; a voice producing unit that produces at least one produced voice data item for each of the plurality of voice guidance phrases from the plurality of stored voice data items using voice synthesis, wherein each of the plurality of stored voice data items and the at least one produced voice data item of a first voice guidance phrase of the plurality of voice guidance phrases has a different frequency; a voice mixing unit that mixes at least two voice data items from the first voice guidance phrase to thereby produce a first mixed voice data item of the first voice guidance phrase; a voice outputting unit that outputs and sounds only the first voice guidance phrase using a first mixed voice for the first voice guidance phrase based on the first mixed voice data item; a voice detecting unit that detects a response voice responding to the outputted first voice guidance phrase using the first mixed voice; and a voice measuring unit that measures a frequency with respect to the detected response voice; the voice mixing unit producing a second mixed voice data item by mixing at least two voice data items of a second voice guidance phrase of the plurality of voice guidance phrases, different than the first voice guidance phrase and different from the detected response, the second mixed voice data item having the characteristic of the frequency that is measured by the voice measuring unit with respect to the response voice detected after the first mixed voice was sounded; the voice outputting unit further outputting and sounding only the second voice guidance phrase using a second mixed voice based on the second mixed voice data item in response to the response voice, the second voice guidance phrase approximating the frequency that is measured by the voice measuring unit with respect to the response voice. 14. A navigation device including the voice guidance device according to claim 8 .