While most high-end in-ear headphones rely on mechanical noise reduction to block external sounds, the Phiaton PS 20 NC in-ears also use electronic noise cancellation to do the job. This should allow great noise reduction and could also help tune the noise reduction to particularly difficult frequencies (e.g. the 125 Hz drone of an aircraft engine).
Phiaton claims that the Noise Blocker technology attenuates 95% of the external noise from the environment. In addition, the signal processing circuitry is set up so that the headphones continue to work even if the Noise Blocker battery runs out of power.
The PS 20 NC is designed for use with mobile devices. The impedance is 26 ohms, which makes them appropriate for iPhones and the like. The sensitivity is specified at 101 db, but with no input level. However testing showed that an iPhone could easily drive the PS 20 NC to satisfying volume levels and (gulp!) beyond.
EASE OF USE
The active-plus-passive noise cancelling approach is the one typically used by larger over-the-ear headphones, of course, and it has also been applied on occasion with in-ear ‘phones. With the PS 20 NC, part of the focus of the active technology is on ease of use.