Tests / 08 — Phase / polarity
Phase / polarity test
The same noise plays in both ears. In phase, it forms a tight ball in the center of your head. Flip one channel’s polarity and it smears into a wide, hollow “everywhere” sound. Learn the difference once and you’ll never unhear it.
Switch back and forth while the noise plays. The difference should be obvious within a second.
What you should hear
- In phase: a compact, solid image dead-center between your ears.
- Inverted: diffuse, hollow, hard to locate — some people describe it as “inside-out” or pressing outward on the ears.
Why you’d run this on real headphones
If the button marked In phase is the one that sounds hollow, one of your drivers is wired with reversed polarity — it happens with hand-terminated cables, repairs, and occasionally factory defects on cheap pairs. Music on such a pair has weak, vague bass and no stable center image, yet nothing sounds obviously “broken”, which is why it goes unnoticed.
The mono trick
Inverted channels cancel when summed to mono. If your phone’s accessibility settings offer mono audio, enable it and replay: a healthy pair gets louder and stays clean; a polarity-flipped pair turns thin and quiet — the two channels are subtracting from each other.
This also matters beyond headphones: audio engineers check mono compatibility for exactly this reason, and a speaker pair with one flipped cable loses nearly all its bass.