I would like to personally thank Dave Hoffman, the creator of the JJ Spotter Pack for gracing us with another great addition to the sim-racing world.
He is working on a possible add-on to have Chad Knaus as Crew Chief with Earl Barban as Spotter that will work for the Crewchief app, but in the meantime has already created and made available for us to download the Earl Barban Spotter pack.
This forum won't allow me to post a link but you can get it at DWarehouse.com
NOTE: ((Some browsers and anti-virus programs block or warn against going to this site but I have found to be perfectly safe))

Earl Barban spotter pack for CrewChief
I have ported over all the Earl spotting sound from the JJSP into CrewChief. To use it, obviously install the CrewChief app if you haven't already. Then just run the EBSP installer and it should drop the "spotter_Earl" folder where it needs to go, which is in with the other stock CrewChief spotter folders. Or you can grab the .zip file, and manually extract it there yourself. I believe it goes to: \(user)\AppData\Local\CrewChiefV4\sounds\voice

When you open the CrewChief app, you should then be able to select Earl from the list of available spotters. His volume seems a little low to me, compared to the Crew Chief, so I would suggest going into the app Properties, and bumping the "Spotter Volume Boost" to 2. The setting is all the way at the bottom.

Once in the sim, I lower the sim spotter volume to 0 with the hot keys, and all I hear is what CrewChief provides. That seems like the easiest way.