15. The computer-implemented method of claim 9 , wherein determining the length of time required to output audio content corresponding to the determined segment of textual content comprises determining a length of time required to output audio content without generating audio content corresponding to the determined segment of textual content.
16. The computer-implemented method of claim 15 , wherein determining the length of time required to output audio content corresponding to the determined segment of textual content without generating audio content corresponding to the determined segment of textual content comprises estimating a length of time required to output audio content based at least in part on at least one of a number of words in the segment of textual content, a number of syllables in the segment of textual content, a number of phonemes in the segment of textual content; a number of letters in the segment of textual content, a number of spaces in the segment of textual content, or a length of words in the segment of textual content.