Subject: How can I measure reading comprehension? What kinds of music are suitable?

I am doing an experiment on how music affects reading speed and 
comprehension. I am going to test with various types of music, but i don't 
know which. I want to include as a variable if the music has a singer or 
if it is instrumental. 

Also, i am going to do the test with a reading material, but i dont know 
if i should separate the material in phases (one for each kind of music) 
or use the material as one piece and ask the people that are taking the 
test to mark where they finished after each music segment. This problem 
occured to me when thinking about the comprehension test, How am i going 
to test the comprehension of each individual segment?

Please reply as soon as you can.

Thank you for your attention, 
                            Javier

Re: How can I measure reading comprehension? What kinds of music are suitable?