Practicing with the radio

During my commutes, I listen to NPR ripped to my iPod, and use a patch-cord to jack directly into the BTE. I'm following 90 percent of shows and even higher when I re-listen to difficult passages with foreign accents or noisy recording; after a second passage, comprehension goes to the max. When jacked in via the patch cord, and the sensitivity set to 0, there is no interference from noises around me. To teach myself to listen in noisy surroundings, I'm slowly increasing the sensitivity wheel, thus increasing ambient sound.