Owen PalmerBy Owen Palmer

Updated November 2026

The Bose QuietComfort 20 acoustic noise cancelling headphones are in-ear models that use a passive seal plus an active noise cancelling circuit to reduce steady background sound. When they sound thin, leak noise, or seem to cancel less than expected, the cause is usually fit, a worn or dirty ear tip, low battery, or a mismatch between the audio source and the headphones. Most of these problems can be checked in a few minutes without any tools.

Why the quietcomfort 20 acoustic noise cancelling headphones seem to lose performance

Owners of quietcomfort 20 acoustic noise cancelling headphones often describe the same pattern: the first few weeks sound full and quiet, then the bass fades or the room noise starts creeping in. Noise cancelling works by combining a passive seal with an active circuit, so a small loss of seal can make a big difference. Because the QuietComfort 20 uses in-ear tips rather than a large over-ear cup, even a slightly wrong tip size lets low frequencies escape.

Shopping for one? See our guide: Bose QuietComfort Ultra Noise Cancelling Headphones Review: Is It Worth It?.

Some reported drops in performance are not a fault at all. Air travel, a loud train, or a low-frequency engine hum are the hardest sounds to cancel, and active circuits are weakest against steady rumble. Knowing which sounds are realistic to reduce helps you judge whether the headphones are actually failing.

The factors that affect fit, seal and sound

Three factors decide most of the experience with quietcomfort 20 acoustic noise cancelling headphones:

  • Ear tip size. Bose supplies multiple silicone tip sizes. A tip that is too small leaks sound; one that is too large can feel tight and push the earpiece out of position over time.
  • Insertion angle. The earpiece should sit angled toward the ear canal, not straight in. A shallow fit usually gives thin bass.
  • Battery and source. Noise cancelling draws more power than passive listening. Low battery can reduce how much the active circuit does, and a low-quality cable or source can make the sound harsh.

Earwax and debris in the mesh openings can also reduce output. Ear tips slowly harden or lose shape after months of use, which is one of the most common reasons owners see a drop in seal.

What to do about it

Start with the simplest checks and work toward the more involved ones. Most people find the fix in the first two steps.

  1. Remove the ear tips and inspect them. Replace any that are cracked, sticky, or visibly stretched.
  2. Test each size in turn. Insert the earpiece, twist slightly, and play a bass-heavy track. Choose the size that gives the fullest low end without discomfort.
  3. Clean the mesh grilles and tip openings with a dry soft brush. Do not push anything into the openings, and never use liquid directly on the speaker.
  4. Charge the headphones fully and compare performance again.
  5. Reset the connection: unpair from your phone, forget the device, and pair again.
  6. Check the app or device settings to confirm noise cancelling is switched on and not in a transparency or passive mode.
  7. If the problem continues after these steps, contact Bose support with your model details and the purchase date.

Practical tips

  • Keep the carrying case closed when not in use to avoid lint and dust in the tips.
  • Wipe the tips with a dry cloth after workouts to prevent build-up.
  • Replace tips every few months if you use the headphones daily.
  • Test noise cancelling in the same environment each time so comparisons are fair.

What we’d use

If your existing ear tips have worn out, a set of replacement silicone tips in multiple sizes is the most direct fix for a loose seal. Search for the matching Bose tip set rather than generic tips, since diameters vary.

A soft-bristled cleaning brush designed for earbuds helps keep the mesh openings clear without pushing debris deeper. View on Amazon

A compact travel case protects the headphones and keeps the tips from collecting lint in a bag. View on Amazon

For a broader view of how these headphones fit alongside other models, see Bose QuietComfort QC25 Noise Cancelling Headphones: Model Guide, Fixes and Tips and Bose Qc25 Quietcomfort 25 Acoustic Noise Cancelling Headphones: A Practical Guide (2026). If you are comparing brands, Sony Versus Bose Noise Cancelling Headphones: Which Fits You Best (2026) covers the main differences.

Can the quietcomfort 20 acoustic noise cancelling headphones damage my hearing?

Noise cancelling itself does not add volume, but any headphones played loudly can contribute to hearing strain. Health guidance generally recommends keeping volume moderate and taking breaks. Consult a hearing professional if you notice ringing or discomfort.

Why do my headphones feel loose during exercise?

Movement can break the seal. Try a tip size one step larger or a secure-fit tip, and make sure the earpiece is angled toward the canal.

Do I need to reset the headphones after an update?

Restarting the headphones and reconnecting to your device usually clears temporary glitches. Keep the companion app updated so the controls behave as expected.

Is passive isolation enough on a plane?

A good seal blocks higher frequencies well, but engine rumble is easier to reduce with active noise cancelling. Make sure the mode is set correctly before boarding.

Ready to choose one?

Owen Palmer

About Owen Palmer

Owen Palmer is part of our editorial team and reviews and edits our brand headphones & noise cancelling guides, checking product details against manufacturer specifications and owner feedback.