Noise-canceling headphones continue to improve. Bose has come out with the Quiet Comfort 2 headphones, which drown out unwanted sounds, like airplane drone and treadmill chatter, more effectively than its first model, for the same cost of $300. The 2 also has a single cord instead of a tangle-prone double cord, earcups that fold flat enough for a briefcase, and no bulky battery box. Taking a more low-tech approach, Etymotic Research, a small Illinois outfit known for its professional-grade earplugs, has introduced earplug-style headphones. The ER-4P ($330) slips into the ears instead of over them, reducing noise so effectively you can listen to classical guitar at a low volume. The only knock is that the cord produces a "microphone effect" if tapped or rustled. But Etymotic is currently developing a way to fix that. 888-275-2073, www.bose.com; 888-389-6684, www.etymotic.com.