A computer-implemented method when executed on data processing hardware causes the data processing hardware to perform operations comprising: during a registration process for a client device (106a, 106b, 208): receiving demographic information for a user (102a, 102b, 202) of the client device (106a, 106b, 208); and designating a language proficiency to the user (102a, 102b, 202) based on the received demographic information, the language proficiency designated to the user (102a, 102b, 202) comprising one of a first level of language proficiency or a second level of language proficiency different than the first level of language proficiency; receiving a voice query (104, 204) input to the client device (106a, 106b, 208) by the user (102a, 102b, 202); generating audio data comprising a synthesized utterance of a particular text segment responsive to the voice query (104, 204) and based on the language proficiency designated to the user (102a, 102b, 202), the particular text segment comprising one of: a first text segment when the language proficiency designated to the user (102a, 102b, 202) comprises the first level of language proficiency, the first text segment comprising primary information responsive to the voice query (104, 204); or a second text segment when the language proficiency designated to the user (102a, 102b, 202) comprises the second level of language proficiency, the second text segment comprising additional information responsive to the voice query (104, 204) that is not included in the first text segment; and providing the audio data for audible output from the client device (106a, 106b, 208). during a registration process for a client device (106a, 106b, 208): receiving demographic information for a user (102a, 102b, 202) of the client device (106a, 106b, 208); and designating a language proficiency to the user (102a, 102b, 202) based on the received demographic information, the language proficiency designated to the user (102a, 102b, 202) comprising one of a first level of language proficiency or a second level of language proficiency different than the first level of language proficiency; receiving demographic information for a user (102a, 102b, 202) of the client device (106a, 106b, 208); and designating a language proficiency to the user (102a, 102b, 202) based on the received demographic information, the language proficiency designated to the user (102a, 102b, 202) comprising one of a first level of language proficiency or a second level of language proficiency different than the first level of language proficiency; receiving a voice query (104, 204) input to the client device (106a, 106b, 208) by the user (102a, 102b, 202); generating audio data comprising a synthesized utterance of a particular text segment responsive to the voice query (104, 204) and based on the language proficiency designated to the user (102a, 102b, 202), the particular text segment comprising one of: a first text segment when the language proficiency designated to the user (102a, 102b, 202) comprises the first level of language proficiency, the first text segment comprising primary information responsive to the voice query (104, 204); or a second text segment when the language proficiency designated to the user (102a, 102b, 202) comprises the second level of language proficiency, the second text segment comprising additional information responsive to the voice query (104, 204) that is not included in the first text segment; and a first text segment when the language proficiency designated to the user (102a, 102b, 202) comprises the first level of language proficiency, the first text segment comprising primary information responsive to the voice query (104, 204); or a second text segment when the language proficiency designated to the user (102a, 102b, 202) comprises the second level of language proficiency, the second text segment comprising additional information responsive to the voice query (104, 204) that is not included in the first text segment; and providing the audio data for audible output from the client device (106a, 106b, 208).