Converting text into voice output using speech synthesis techniques. Although initially used by the blind to listen to written material, it is now used extensively to convey financial data, e-mail messages and other information via telephone for everyone. Text-to-speech is also used on handheld devices such as portable GPS units to announce street names when giving directions. Early text-to-speech (TTS) systems had a very robotic sound; however, with the advent of high-speed chips and advanced software techniques, text-to-speech has become much more natural. See screen reader.