Controlled signal
The tool generates the test inside your browser with a bounded app-level gain. Your operating-system and hardware volume remain separate.
Online Phase Test
In-phase playback usually forms a focused center. Out-of-phase playback often feels diffuse or outside the speakers. The comparison is more useful than either sound alone.
Compare the two states at the same volume. A mono path may cancel the out-of-phase signal almost completely.
Local by default
Output tests do not upload audio. Microphone tools request permission only when started and explicitly state what stays in memory.
SCOPE / 01
What this test checks
The phase test sends matching signals to both channels, then reverses the polarity of one channel. A normal stereo path usually preserves a clear contrast between a focused in-phase center and a diffuse out-of-phase image.
- Stereo sounds hollow, unfocused or unexpectedly weak in the center.
- Checking speaker wiring, mono summing or a channel-processing path.
- Whether the digital signal is generated with matching or opposite channel polarity.
- Whether your current playback path preserves an audible contrast between the two states.
- Whether mono summing causes strong cancellation of the out-of-phase signal.
- Which physical cable is reversed without your wiring observations.
- Medical hearing symmetry or absolute acoustic phase through the room.
PROCEDURE / 02
How to run this test
Keep the level moderate and change one thing at a time so the result remains useful.
- 01
Sit centered between speakers or wear headphones correctly.
- 02
Play In phase and note center focus and bass.
- 03
Play Out of phase and compare width and stability.
- 04
If the expected contrast is absent, check mono mode and wiring.
INTERPRETATION / 03
What your result means
Match what you heard or saw, change one variable, then use the linked check to verify the result.
| Observation | Likely cause | Next step | Retest |
|---|---|---|---|
| 01In phase is focused and out of phase is diffuse. | The stereo relationship is being preserved and the comparison is behaving as expected. | Use this as the reference result after changing wiring, balance or spatial settings. | Confirm the stereo center |
| 02Both states sound almost the same. | A single speaker, mono path, channel-combining adapter or strong spatial processing may be removing the contrast. | Disable mono and spatial effects, confirm both channels work separately, then compare again. | Check left-right separation |
| 03In phase remains hollow or diffuse. | One speaker may have reversed polarity, placement may be asymmetric or a processing stage may be altering one channel. | Check speaker cable polarity and bypass widening effects before retesting from the center position. | Check unbalanced output |
| 04Out of phase becomes extremely quiet or silent. | The playback path is likely summing left and right to mono, causing opposite-polarity signals to cancel. | Confirm whether Mono Audio is enabled or the device has only one physical output channel. | Understand mono versus stereo |
VARIABLES / 04
Why results can vary
The generated signal stays controlled; the physical device, room and system path can still change what reaches you.
Mono summing
Combining left and right can cancel the out-of-phase signal almost completely.
Headphones versus speakers
Headphones isolate each ear, while speakers interact through the room and reach both ears.
Listening position
Moving away from the center line changes timing and level, weakening the expected speaker comparison.
Wiring and processing
Reversed cable polarity or spatial effects can alter center focus without changing basic left-right routing.
LIMITS / 05
Browser limits and safety
Online Phase Test questions
What does out of phase sound like?
It commonly sounds wide, hollow or difficult to locate, with a weaker center.
Can phase damage speakers?
No at normal listening levels; it changes channel polarity, not the allowed output level.
Why is out-of-phase silent on one device?
A mono path may cancel opposite-polarity signals.