Speech synthesis is the artificial production of human speech. A
computer system used for this purpose is called a speech synthesizer,
and can be implemented in software or hardware. A text-to-speech (TTS)
system converts normal language text into speech.

Most of the text-to-speech softwares can read text files in format
of .txt and other file formats with natural voices using various voice
engines. The text-to-speech voice engine on Vista is Microsoft Anna,
and Microsoft Sam on the Windows XP. Vista users can hear a very clear
voice of Anna, XP users would think the voice of Microsoft Sam is
poor, but they can get other company's vocie engines which are more
clear.

The narrator has been shipped with Windows XP and Vista. However some
users choose panopreter (www.panopreter.com) which is a freeware. It
is an easy-to-use tool which reads files, words you type and converts
files into wave and mp3 audio files, so you can listen to them with a
MP3 player. It's a effective way to improve listening, somehow they
are educational softwares for language learning.