Design and features:The earplug-like design and electronic noise cancellation of this portable ear-insert model reduce both outside noise and sound leaking out into your environment. The headphones work with or without the noise-canceling feature being turned on. You can use the noise-canceling feature without listening to music, but the audio cable can't be detached when the headphones are being used for noise reduction only. The earphones have medium-high sensitivity with the noise cancellation turned on, so they can provide satisfying volume levels even when used with lower-powered portable audio devices. When the noise cancellation is turned off the earphones have medium sensitivity, so they can provide satisfying volume levels when used with all but the lowest-powered portable devices. The QuietComfort 20i is designed to work with iOS devices. (The QC20 model is designed to work with Android and Blackberry devices.) It has an inline volume control that works with iPads and some iPod and iPhone models, plus an integrated microphone and player function controls that are compatible with iPads, some iPods, and some iPhones and some other cell phones. The call connect/disconnect button can be used with some iPhones and some other cell phones. These earphones may not operate properly with some non-iPod players or other audio equipment. This model comes with three pairs of "Stayhear + Tip" ear bowl support earpieces of various sizes, a USB charging cable, a shirt clip, and a carrying case.
Sound quality: With the noise cancellation engaged, the QuietComfort 20i delivers very good overall sound with a warm character, and excellent active noise reduction. Bass has good impact but is slightly pronounced and a bit thumpy. Midrange is even but a bit grainy, treble is recessed, and upper treble is rolled off. Overall sound is somewhat open, with good dynamics. When the noise-cancelation feature is turned off, the sound quality drops to fair-- bass is more pronounced, thumpy, and boomy, and midrange and treble are muffled compared than with that feature turned on. These earphones provide excellent reduction of low-frequency noise, and it ranged from very good to excellent with midrange and treble frequency noise. With the noise cancellation engaged, a faint hiss can be heard in very quiet environments when there's no music or speech playing through the headphones to mask it, and the earphones are susceptible to picking up hum when used with or near some AC-powered equipment.
Comfort: These earphones have a hybrid ear-insert/earbud design: The earpieces seal the ear canals but they don't insert into the ear canals as far as typical ear-insert models. They are also supported by the ear bowls, like an earbud model. They fit and stay in place with no problem, and the ear-bowl-support earpieces make them very stable, even with vigorous head movement. They are comfortable to wear as long as the shirt clip is used or the battery/sound module is supported; otherwise the module pulls on the earphones.
