Symptoms
- Faint background hiss noticeable mainly in quiet environments with ANC on
- Hiss disappears when ANC is turned off
- Hiss is louder in one ear than the other
- Hiss seems louder than when the earbuds were new
Likely causes
- CommonInherent self-noise from the ANC microphones and processing circuitActive noise cancelling requires constant microphone monitoring and signal processing, which can produce a low-level hiss especially noticeable in silent rooms.
- CommonANC strength/level set to maximum, amplifying the self-noiseSome earbuds let you adjust ANC intensity, and higher settings can increase perceptible hiss.
- PossibleFirmware bug affecting ANC processing on a specific unitOccasionally a firmware issue causes ANC hiss levels higher than the model's normal spec.
- PossibleManufacturing variance between unitsA small percentage of units may have a slightly noisier ANC circuit than the average for that model.
- Less commonDamaged ANC microphone causing excess noiseA degraded or damaged microphone component can generate more noise than intended.
What to do
- Compare the hiss level to reviews or forum discussions for your exact earbud model, since some baseline hiss with ANC is normal and expected.
- Try reducing the ANC intensity level if your earbuds offer adjustable strength settings.
- Update the earbuds' firmware, since ANC processing improvements are sometimes included in updates.
- Test in a genuinely silent room versus normal environments, since hiss is far more noticeable without any ambient sound to mask it.
- Compare the hiss level between left and right earbuds individually to check for an asymmetric issue.
- If hiss seems unusually loud compared to when the earbuds were new or compared to typical reviews, consider a factory reset.
When to call a pro
If the hiss is clearly louder than typical for your model (as described in reviews) or is asymmetric between ears after a firmware update and reset, contact the manufacturer's support to check for a hardware defect.
Safety
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.