Shure today launched the latest in its high-end earphones: the are the new flagship for its E Series product line. The new sound-isolating and noise-canceling headphones offer a new "Push-to-Hear" option that lets users alternate between complete isolation and a connection with the outside world. Shure's new modular Push-to-Hear (PTH) accessory allows consumers to alternate between complete immersion in their music or a connection with outside ambient sounds by activating an external microphone, while simultaneously muting the music. Shure's PTH is also sold separately for $60 and can be used with any sound isolating earphones. Shure says its sound-isolating earphones block 30-37dB of outside noise with a good seal and the earphones utilize 3 miniature precision-engineered drivers -- one tweeter and two woofers -- to offer accurate audio reproduction. The E500 will begin shipping in May for $500.