SayItNow is a free tool which can read English text aloud naturally.
This software works with copy-paste text or a website address.
It supports English text to speech conversion based on Microsoft Windows TTS Engine.
The output voice can be played on your speakers or redirected and saved in WAV files stored on your PC.
SayItNow has the ability to generate multiple files on a one file per line basis (suitable for generating one file per word/sentence). Thus you can create voice files based on your list of word or sentences in a minute.