The device itself does not have a speaker built into it. To hear sound, you need to connect some kind of speaker to it - either a headset, earphone, or small amplified spearker. I don't know whether the Navigator II comes packaged with a Garmin automobile 12 volt power outlet that includes a speaker with it. If you do have a cable that has what looks like a very large 12 volt plug on the end of it, go plug that into your car, and hook the GPSR up there - see if you get any sound out of the speaker that is integral to the 12 volt plug.
Michael