Polarity ABX Test — Phase Drill
Can you truly hear 180° polarity inversion on music? Double-blind ABX trials with asymmetric waveforms test absolute phase. Free in your browser, no download.
Protect your hearing. Start at a low volume. Never raise the volume to make a tone audible. Levels are shown in dBFS, relative to full scale — not SPL.
How it works
Double-blind ABX polarity test comparing normal and 180° inverted acoustic asymmetric waveforms.
Absolute Phase & Polarity
When an acoustic instrument produces sound, the initial wave front compresses air molecules outward toward the listener’s eardrum.
- Positive Polarity (+): The loudspeaker cone pushes forward on the attack transient, causing an initial condensation (positive pressure) in the room.
- Inverted Polarity (-): The cone pulls inward, creating an initial rarefaction (negative pressure).
Because human hearing organs (the ossicles and basilar membrane) possess physical asymmetric damping, asymmetric waveforms often sound subtly punchier or firmer in one polarity orientation.
Frequently asked questions
What is the difference between phase and polarity?
Polarity refers to inverting the electrical or digital sign of every sample (+ becomes -, - becomes +), representing a 180° inversion across all frequencies simultaneously. Phase shift depends on frequency and involves a time delay.
Is absolute polarity audible to human ears?
On symmetrical sine waves, polarity inversion is mathematically inaudible in isolation. However, real-world sounds (brass, human speech, kick drums) are highly asymmetric. Due to middle-ear mechanical nonlinearities and asymmetric speaker cone suspension, many listeners can reliably hear absolute polarity.
Why does polarity matter in studio production?
If two microphones record the same snare drum (top and bottom) with opposing polarity, summing them to mono causes severe low-end phase cancellation.