There are two ways to cut out ambient noise.
The first is to buy a pair of earphones that wedge into your ear canal. The second is to buy headphones that cut out ambient noise with phase-inversion technology. Step forward the PXC 350s...
Effective noise-cancelling
Phase-inversion is a noise compensation system developed for pilots to cut out the persistent background drone of the engines and turbulence. Tiny microphones pick up low-frequency noise near the ear as you would hear normally.
The electronics then generate a sound wave that is at the same volume level but out-of-phase by 180 degrees. This cancels out most of the outside noise, which to the listener is perceived as near silence.
It's not absolute cancelling because some ambient noises come and go suddenly, but it works very well in situations where an engine is droning away a few meters from your ears. A volume control has been embedded into the cable to add a level of convenience.
Superb sound quality
The sound quality from the PX350 is excellent with or without the Sennheiser's NoiseGard (phase-inversion) technology switched on. A flick switch is located on the left can. A travel pouch and two AAA batteries are included.
The PXC 350s are a wired offering and not BlueTooth. The main downside is the bulkiness of the headphones. But if you frequently take long journeys then the benefit in cutting out noise might outweigh the inconvenience of lugging them about.
Tight fitting ear phones may save space but if you can make room for some headphones, you could do a lot worse than Sennheiser.