I don't if they have any speech clips of use to you but a good site for
a variety of sound clips (including a few speech recordings) under the
creative commons license is Freesound.
http://freesound.iua.upf.edu/
You may also look for some free audio books. You may find the licenses
acceptable for your use. I have used some readings from a Children's
book for auralizing reverberation.
http://www.audiobooksforfree.com
http://www.gutenberg.org/audio/
Ralph Muehleisen
Assistant Professor, Civil and Architectural Engineering
Illinois Institute of Technology, Chicago, IL 60616
Tel:312-567-3545 Fax:312-567-3519
EMAIL::muehleisen@xxxxxxx