I recently bought a pair of Bose QC 2 and also a pair of Bose QC 3 on ear headphones for myself and my wife. On a recent flight we compared the two in terms of noise reduction and sound quality.

When it comes to quality of reproduced sound from our Ipod and from my Dell laptop both the QC2 and QC3 were nearly identical in terms of richness, bass, and treble. I noticed slightly better sound from the over the ear QC2 than the on ear QC3.

When it comes to engine noise both models block out much of it using electronic cancelling that samples the incoming sound hundreds of times per second and sends out an opposite cancelling sound wave to absorb it.

Unfortunately the noise cancelling feature does not seem to work quite as well for high frequency sounds such as a baby crying, but still they cancel out much of high frequency sounds and life can be bearable with them on if you have a crying infant nearby.

I noticed that the over the ear models blocked out high frequency sounds such as the "ding" from the speakers and children crying more than the on ear Bose QC3.

In the seat next to us was a child with a Game Boy that emitted high frequency sounds. With the over the ear headphones on I could not hear it at all and with the QC2 on ear headphones on I could barely hear it in what seemed like the distance.

However when it came to the low frequency sound of the jet engine both headphones seemed to block it equally.

For frequent travellers I can imagine no better gift than a pair of either the Bose QC2 or Bose QC3 since they make air travel a more peacful experience overall.