15. A computing device comprising: one or more processors; and a memory including instructions operable to be executed by the one or more processors to perform a set of actions to configure the device to: output first audio including an audio tone preceded by first synthesized speech and followed by second synthesized speech, the audio tone associated with an indicator of first secondary content located in a string of text and based on a type of the first secondary content, the first synthesized speech associated with a portion of the string of text prior to the indicator and the second synthesized speech associated with a portion of the string of text following the indicator; detect first contact on a touch-screen of a computing device; determine that the first contact corresponds to a first arc gesture, the first contact extending along both a horizontal axis and a vertical axis from a first point to a second point, a difference between a first horizontal coordinate associated with the first point and a second horizontal coordinate associated with the second point exceeding a horizontal threshold in a first direction relative to the first point, and a difference between a first vertical coordinate associated with the first point and a second vertical coordinate associated with a midpoint of the first contact exceeding a vertical threshold; select the first secondary content that corresponds to the first arc gesture; identify supplemental text associated with the first secondary content; and output second audio corresponding to the supplemental text in response to the first arc gesture.
15. A computing device comprising: one or more processors; and a memory including instructions operable to be executed by the one or more processors to perform a set of actions to configure the device to: output first audio including an audio tone preceded by first synthesized speech and followed by second synthesized speech, the audio tone associated with an indicator of first secondary content located in a string of text and based on a type of the first secondary content, the first synthesized speech associated with a portion of the string of text prior to the indicator and the second synthesized speech associated with a portion of the string of text following the indicator; detect first contact on a touch-screen of a computing device; determine that the first contact corresponds to a first arc gesture, the first contact extending along both a horizontal axis and a vertical axis from a first point to a second point, a difference between a first horizontal coordinate associated with the first point and a second horizontal coordinate associated with the second point exceeding a horizontal threshold in a first direction relative to the first point, and a difference between a first vertical coordinate associated with the first point and a second vertical coordinate associated with a midpoint of the first contact exceeding a vertical threshold; select the first secondary content that corresponds to the first arc gesture; identify supplemental text associated with the first secondary content; and output second audio corresponding to the supplemental text in response to the first arc gesture. 17. The computing device of claim 15 , wherein the instructions further configure the device to: generate supplemental synthesized speech corresponding to the supplemental text, the supplemental synthesized speech having different voice parameters than at least one of the first synthesized speech and the second synthesized speech, wherein the second audio includes the supplemental synthesized speech.