The Backstreet Boys, 'N Sync, and Mandy Moore are undoubtedly Orlando's leading claims to pop fame. But a newcomer is threatening to add its name to the roster. The rock quartet Big 10-4 makes what might kindly be called bubblegum-flavor crack disguised as music. After getting their start from a string of opening acts, the O-Town boys each irresistibly doe-eyed and shaggy-haired, natch have graduated to headlining status.The foursomes debut album, Testing the Atmosphere, showcases twelve tracks perfectly suited to the wide range of teen emotions. For those in the throes of their first romance, there is Oxygen, a sensitive piano ditty for young lovers. The albums first single, Walking Disaster, is an anthem for the angst-ridden, with its alt-rock edge and lyrics that fairly scream self-doubt and confusion. Big 10-4s radio-friendly sound might be something youd expect to hear in the background as your little sister watches Laguna Beach, but dont be surprised if you find yourself not only singing along but also learning every word.