My Intermountain F7A with DCC & Sound arrived, & I am learning what my E-Z Command's function buttons will do.  I am enjoying it.  Some sounds are automatic, like the engine starting up & idling & the sound like air being released.  F1 rings the bell.  F2 blows the horn until I press it again.  There is a sound like couplers & a sound like cars jerking each other forward.  F8 lowers the volume.  I can turn some lights on & off, but I don't seem to be able to dim them or turn all of them off, as I can with my Spectrum SD-45 DCC.
  The Quantum QSI manual says that F10 reports the address in neutral & the scale speed when in motion!  I'd love to hear a voice reporting the mph, but F10 turns the headlights on & off, instead.  There seems to be a magnetic wand for moving a lever in the locomotive to change the master volume.  I can see the opening on top of the locomotive where the sound comes out.
  What I haven't been able to do, as I reported in the HO discussion, is get E-Z Command to change either of my DCC locomotives from Address 3 to another address.

SteamGene,
  Thanks for the information about lengths of passenger cars & eras.  I got out some of my 3-rail curved track for my Marx 0 set, laid them along the 18"r HO track & found that the Marx track has a slightly sharper curve, which is why 18"r seems normal to me.

  I do get the LED light flashing quickly when I press 3 & Stop simultaneously & release them simultaneously, but when I press Address 1, the LED does not flash slower & the locomotive does not move.

  I have been running my Spectrum EMD SD-45 with DCC on the default address 3 of E-Z Command.  Today, I got an Intermountain F7A DCC/with sound.  Following the E-Z Command instructions, I press Stop & 3 simultaneously; then I press Address 1 & press Stop again, but the Intermountain locomotive does not run at the new address.  I tried the Bachmann locomotive, which certainly ought to respond to a Bachmann DCC controller, but it does not change address, either.  This leaves me with two trains running at the same address on different ovals connected by switches.
  I also tried the instructions for re-programming a locomotive from a different address than 3 & the instructions for re-programming a locomotive with an address higher than 10.   I had more control when one locomotive was DC.

Guilford Guy,
  Thanks!  Plug & play is something I think I can do.

  Thanks for the recommendations & explanations about couplers.  I have invested a lot of money just getting started, so I will have to defer changing to EZ track, which is more expensive than Power-Loc, for a while.  Too bad Bachmann didn't have a train set in my local Fleet Farm, where I found the Walthers train set.
  A set of 8 smooth passenger cars, 11" each, makes a long train!  I had originally chosen heavyweight, not knowing the difference in length, but the train person at the hobby store explained that the era I want is the era of smooth cars.  Actually, I have 6 IHC smooth & 2 Athearn heavyweight cars (which have knuckle couplers).  Maybe I should switch to the era of shorter cars.
  Today, the Intermountain 49009S HO RTR F7A w/ DCC & Sound, GN I ordered is due to arrive, along with my first 2 GN freight cars.  I am eagerly awaiting it to replace my Walthers train set F7 for my passenger train.

 Guilford Guy,
  Thanks for the link.  Sound costs twice as much as my SD-45!  Since 72442 says it's for SD-45s, the speaker ought to fit.

 Would the long shanks on my IHC passenger cars' couplers have something to do with these 11" cars being able to run on 18"r curves, & does close coupling require wider curves?  I saw some Walthers' passenger cars with a caution that they be run on no sharper than 24"r curves.  I haven't seen any 24"r Power-Loc track.  I have just added an oval around my original one using 22"r curves for my passenger train & leaving the inner oval with 18"r for my freight train.

Eric, I now have the E-Z Command Control & am enjoying it.  I like that my DCC locomotive remembers what speed I left it at when I switch to the DC locomotive's address to regulate its speed to avoid collisions.

 Thanks for the explanation of the various options.

 Wait, Guilford Guy, your link took me to the model I own!  It wasn't advertised as having sound, & I haven't gotten any sound from it by pushing program numbers F2 through F9 on my E-Z Command.

 Thanks, Guilford Guy!  In the September Model Railroader, I read an article about installing sound, but it still left me with questions.

  Seeing DC locomotives with sound advertised makes me curious how they work vs DCC locomotives with sound.

 Is there a decoder with sound for a Spectrum EMD SD-45 with DCC?

 Instead of lead birdshot, I thought, why not use BBs, which are steel & easier & safer to handle?  So I bought BBs.  They are much more expensive than pennies.    Covering the bottom of an 11" car to distribute their weight evenly, however, made the car about an oz heavier than its optimum weight.  I don't know why birdshot wouldn't have the same result.