Only a handful of talkgroups on the system are analog, mainly fire dispatch and a few other boring things like animal control and the airport janitors. Everything else is Provoice and somewhat more difficult to monitor.
There are 3 ways you can listen...
Buy a Provoice radio on Ebay and find someone that can program it in receive only mode. They can usually be picked up for a couple of hundred bucks, programming is the hard part.
Buy a Uniden BCD436HP or BCD536 scanner and purchase the optional $50 Provoice upgrade key. this will set you back $500-550 or so.
Purchase a couple of RTL-SDR dongles for about $20 each and use some free software to listen in. Cheapest option, but needs to be tied to a computer to work.