The Dell 1702FP doesn't have speakers.The specs of the Dell 1702FP are available here: http://support.dell.com/support/edocs/monitors/1702fp/en/specs.htm
. (BTW neither does the Dell 1704FPT.) However, some Dell monitors can have a sound bar (speaker set-up) mounted on the monitor.
VGA cables don't carry sound. Check if a second cable (an audio patch cable is connected to the computer and the second monitor). (There are some cables that actually bundle the 3.5 mm patch cable with the video cable for convenience. (I've seen a number of DVI cables with that bundle option.) The plugs will separate into separate units at each end.
Other monitors do have speakers built in - look for a 3.5 mm audio
input jack with the rest of the input connections on your monitor. There are some monitors that accept an HDMI input with a 3.5 mm audio
out jack; these monitors don't have speakers and thus are enabling a
daisy chain to connect the speakers to the monitor. So you do need to be
careful and look for the audio in label.
You can attach a set of speakers to your computer using the audio out (look for a lime green 3.5 mm jack on the back of a desktop). For laptops or to use the front audio ports, look for a headphone jack.
I hope this helps. Please add a comment with more information about your monitor and computer for additional assistance.