Talking calculators have a built in speech synthesizer so that as each key is pressed it is spoken out loud. This can help the user to verify that the numbers and operations have been entered correctly. It will also speak the answer to the math problems.
A talking clock or watch is a timekeeping device that presents the time as sounds. It may present the time solely as sounds or a clock for the visually impaired, or may have a sound feature in addition to an analog or digital face.