Online Stereo Test

A stable stereo image depends on correct routing, similar channel level and suitable speaker or headphone placement. This test checks those relationships without claiming to measure the room.

Channel signal bench● Ready — press a channel

App output level-18 dB

Confirm selected signal

The spoken instruction is centered. The tone that follows is the directional test signal. Only your confirmation determines the result.

Controlled signal

The tool generates the test inside your browser with a bounded app-level gain. Your operating-system and hardware volume remain separate.

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

A stereo test compares separate left and right signals with an equal signal sent to both channels. The contrast shows whether the path preserves separation and whether the centered image is stable at your normal listening position.

Use this test when

Vocals, dialogue or game cues pull toward one side despite both channels playing.
You need to confirm that mono mode or spatial processing is not collapsing separation.

It can verify

Whether separate left and right signals remain distinguishable.
Whether equal digital levels form an approximately centered image.
Whether changing fit or listening position changes the apparent balance.

It cannot verify

Laboratory channel matching or room frequency response.
A hearing difference or hardware fault without controlled comparisons.

PROCEDURE / 02

How to run this test

Keep the level moderate and change one thing at a time so the result remains useful.

01
Play the center tone and note where it appears.
02
Compare left and right at the same level.
03
Move to a normal listening position and repeat.
04
Correct balance or placement before judging hardware.

INTERPRETATION / 03

What your result means

Match what you heard or saw, change one variable, then use the linked check to verify the result.

Observed result, likely cause, next step and retest for Online Stereo Test
Observation	Likely cause	Next step	Retest
01The center signal consistently pulls to one side.	System balance, channel gain, speaker distance, headphone seal or reflections may be unequal.	Center all balance controls, use a symmetrical position and see whether reversing the hardware moves the offset.	Diagnose the imbalance
02Left and right signals are difficult to distinguish.	Mono Audio, a single speaker, an adapter or aggressive spatial processing may be combining the channels.	Disable mono and spatial effects temporarily, then run a strict directional check.	Run the left-right test
03The center changes when you move your head or chair.	Speaker distance and room reflections are changing arrival level and timing at the listening position.	Make speaker placement symmetrical and repeat from the intended listening position.	Retest speaker placement
04The center is diffuse even when levels are balanced.	Relative polarity may be reversed or a widening effect may be weakening common center information.	Bypass widening effects and compare in-phase with out-of-phase playback.	Compare phase

VARIABLES / 04

Why results can vary

The generated signal stays controlled; the physical device, room and system path can still change what reaches you.

Listening geometry

A speaker that is closer to the listener arrives earlier and often sounds louder, shifting the center image.

Headphone fit

Unequal pad seal or ear-tip insertion can change both level and bass on one side.

Room reflections

Nearby walls, furniture and screens can reinforce one channel differently from the other.

Mono and spatial processing

Accessibility mixing, virtual surround and widening effects alter the relationship between the channels.

LIMITS / 05

Browser limits and safety