Stenospeed.com has a collection of sound files 
which are arranged by speed.  Some files have accompanying
text.  Most are timed dictation, but some are actual live recordings.
The files are in streaming audio format so you can hear them
when you click the link.  
       In order to hear the sound files, you need a program called 
       If you don't have RealPlayer®, you can download it free 
at http://www.real.com.   Scroll down to the free download section 
and download the program.   Use the back button on your
browser to return here.
      Then read about how to use  Stenospeed.com.