I think only some names with say the street names. HOwever when you pick the name you want, and click select, you wil come to a screen called Speech Preferences. One of the options on this screen is to "Read Aloud Street Names" simply click on this and away you go.
Hope this helps
In addition to choosing "Read Aloud Street Names" in the speech preferences you must choose one of the "Computer Voices" if you want to hear street names. My Tomtom shipped with 4 English speaking comptuer voices (Kate, Simon, Dave, Susan) and when you scroll through all available voices, the screen indicates "Computer Voice" in tiny print. You can use the other voices but street names won't be read aloud.