Amazon.com: Electronics: Panasonic RP-HC70 Noise-Cancelling Headphones
I got to use my new noise cancelling earphones on a flight, and I'm pleased with them. The review said not to expect a miracle, so I didn't but I did get about a 50% noise reduction. The earphones took out the most unpleasant part of the hum, and oddly enough I could hear most of the conversations around me quite clearly. I noticed that my own voice was drowned out somewhat, and my co-work confirmed this - her voice was drowned out too. Overall though, a definite improvement in my flight.
