The fidelity and clarity of these phones are great. This model works with the Treo; I bought a two-legged adapter and a 2.5mm x 3.5mm adapter so I can use them with a computer and an airplane movie. In addition, they isolate you quite effectively from the noise around you. In most cases, I think they are as useful as the PLANEquiet adaptive noise-cancelling headphones I bought especially for plane rides. THe ANC phones may work better with a constant drone, but these seem better in rejecting the snoring and chatting of the other passengers.