3. The voice learning apparatus according to claim 1 , wherein: the learning material voice data includes a plurality of serial learning material voice parts; the learning material text includes a plurality of learning material text parts corresponding to the respective learning material voice parts; the displaying the second text part of the learning material text that has not yet been displayed comprises detecting, from among the plurality of learning material text parts of the learning material text, a learning material text part corresponding to a learning material voice part to be outputted, as a voice-output learning material text part, and displaying a portion of the voice-output learning material text part, the portion including the at least one example sentence text; and the specifying the any one of the at least one example sentence text comprises displaying a range to be displayed by scrolling through the voice-output learning material text part, and specifying the any one of the at least one example sentence text in the voice-output learning material text part as the specified example sentence, in response to the fourth user operation.
3. The voice learning apparatus according to claim 1 , wherein: the learning material voice data includes a plurality of serial learning material voice parts; the learning material text includes a plurality of learning material text parts corresponding to the respective learning material voice parts; the displaying the second text part of the learning material text that has not yet been displayed comprises detecting, from among the plurality of learning material text parts of the learning material text, a learning material text part corresponding to a learning material voice part to be outputted, as a voice-output learning material text part, and displaying a portion of the voice-output learning material text part, the portion including the at least one example sentence text; and the specifying the any one of the at least one example sentence text comprises displaying a range to be displayed by scrolling through the voice-output learning material text part, and specifying the any one of the at least one example sentence text in the voice-output learning material text part as the specified example sentence, in response to the fourth user operation. 4. The voice learning apparatus according to claim 3 , wherein the processor is further configured to perform a process of displaying a list of titles of the respective learning material voice parts, in response to a sixth user operation, and displaying an indicator representing completion of the voice output, the indicator being added to a title of a learning material voice part for which the voice output is completed, from among the displayed titles.