The first time I put these in on a subway platform an L train pulled in next to me, and I watched it pass in something close to silence. That is the demo. Bose has been making this exact moment its argument for thirty years, and the 2nd Gen QC Ultra Earbuds are the version of it that fits inside your ear. The seal is so good that I had to take one out to check whether the train doors had actually opened.
The noise cancellation is the best I have measured in a true-wireless product, by a margin that is small on paper and large in life. Engine rumble, HVAC drone, the dull bass of a coffee shop conversation — all of it disappears in a way that does not feel like the headphones are pressing into your eardrum. The fit is the other half of the same story. The stability bands ship in three sizes and I found a combination that stayed put through a run, which is the first time a Bose earbud has done that for me.
Sound is more complicated. The default tuning has a deep bass shelf that on an EDM track is genuinely thrilling and on a string quartet eats the lower mids alive. There is a three-band EQ in the app and it helps, but it cannot fully undo the choices Bose made at the factory. If you like a forward bass response you will love these. If you are coming from a Sennheiser or a flat studio monitor, you will spend an evening with the sliders trying to claw the mids back into place. Aptx Adaptive and Snapdragon Sound are here for Android users who care, and a firmware update last year finally added multipoint, which I now use every day between my laptop and phone.
The annoyances are the ones every long-term owner eventually hits. The Bose Music app has a special talent for losing connection to the buds for no reason, then needing a relaunch. In a quiet bedroom at night I can sometimes hear a faint white-noise hiss from the ANC circuitry — not loud, but once you notice it you notice it forever. And there is a recurring bug where one bud randomly stops playing audio and requires a re-pair. It has happened to me twice in two months. A forum thread suggests disabling the app's Bluetooth permission on Android fixes it for some people; I have not been brave enough to test that on my main pair.
Battery is the other place these trail. I get a little over six hours on a single charge before the case has to do its job, which is fine for a commute but does not compete with the latest Sony or Apple. The case itself charges quickly and the total runtime of 24 hours is more than enough for a long trip, but if you are someone who forgets to drop them in their case between uses, you will find them dead at moments you did not expect.
The microphone is fine for calls and not for anything else. If you take a lot of meetings in quiet rooms you will be heard clearly; if you call from a sidewalk, your coworkers will hear the sidewalk too.
Verdict: Buy these if silence on a commute is the single most important thing you want from earbuds and you are willing to live with a flaky app. If sound neutrality matters more, the Sennheiser Momentum True Wireless 4 is the calmer pick.