Some don’t, apparently: http://boards.straightdope.com/sdmb/showthread.php?s=&postid=1369885#post1369885
Ricardo Montalban was on The Tonight Show, back in the days of Johnny Carson. He said that to Hispanics who don’t speak English, American English sounds like dogs barking. He then gave a example of “dog barking English” that, I have to admit, fit the general sound and cadence pretty well. Wish I had a tape of it.
Arf!