1. A conversion device, comprising: a segment processing unit operable to (a) select at least one pair of segments from a plurality of segments constituting original audio data and (b) perform segment processing so as to overlap playback periods of the selected pair of segments; and a generation unit operable to generate after-conversion audio data by arranging the overlapped segments and unoverlapped segments in playback order, the unoverlapped segments being remainders of the plurality of segments, wherein along a time axis of the original audio data, a positional relationship between the overlapped segments and the unoverlapped segments is non-linear, one of the overlapped segments is a base segment while the other is a subsidiary segment, the base segment is included in the plurality of segments that are positioned at certain time intervals throughout the original audio data, the subsidiary segment is positioned away from the base segment by a maximum time lag to a minimum time lag, and each of the certain time intervals is greater than the minimum time lag.