English or Chinese?Fortunately here is a free corpus just for your purpose and it recently released a second version. Check it out at:
The Buckeye Speech Corpus Available http://forum.corpus4u.org/showthread.php?t=1999
The corpus itself is available at: http://buckeyecorpus.osu.edu/
You are asked to send them a fax with your personal particulars, and they will send you an email to tell you how to download it. BTW, I've downloaded the latest version last week and it's about 4GB in size.