Speaker Test
Check that your speakers or headphones are wired the right way round. Play left, right and both channels, a 20 Hz to 20 kHz sweep, an in-phase and out-of-phase pair, and each surround channel if your output has them.
How to Use
- Turn your system volume down first. Nothing plays until you press a button, and the page never goes above −18 dBFS.
- Press Left, Right or Both. Each plays a short voice-like sound in that channel only; Alternate plays left, right, left, right.
- Press A/B polarity: the in-phase sound should sit firmly in the middle and the out-of-phase one should sound vague and thin. If it is the other way round, one speaker is wired backwards.
- Run the sweep from 20 Hz to 20 kHz and press Mark when the tone fades. Run it falling too: the two marks bracket the real limit.
- If your output reports more than two channels, a button for each surround speaker appears. Press Stop or Esc at any time.
Volume check before sweeps and high tones. High frequencies at high volume can damage hearing and tweeters, and some people find them unpleasant even when quiet. Set your system volume to about a third, and use the Level slider rather than the system volume to go louder.
A surround test appears here after your first test sound if your output reports more than two channels.
Worked Example
The left-channel test at −36 dBFS. The test signal is normalised to an RMS of 0.2. To play it at −36 dBFS the master gain is 10−36/20 ÷ 0.2 = 0.0792, so the output RMS is 0.2 × 0.0792 = 0.01585, and 20 × log10(0.01585) = −36.00 dBFS. The panner is set to −1, so x = (−1 + 1) ÷ 2 = 0: the left gain is cos(0) = 1 and the right gain is sin(0) = 0. Only the left speaker plays. The page’s ceiling, −18 dBFS, is a master gain of 0.6295.
The 20-second sweep. 20 Hz to 20,000 Hz is a ratio of 1,000, which is log2(1,000) = 9.97 octaves, so the sweep spends 20 ÷ 9.97 = 2.01 s on each octave. At 18.97 s it reaches 20 × 1,00018.97/20 = 14,000 Hz.
The common mistake: trusting one rising mark. Say your real upper limit is 14,000 Hz and you take 0.25 s to press Mark. In 0.25 s the rising sweep climbs 0.25 ÷ 2.01 = 0.125 octave, a factor of 20.125 = 1.090, so the mark lands at 15,263 Hz, about 9 % too high. On a falling sweep the same delay puts the mark at 14,000 ÷ 1.090 = 12,842 Hz. The geometric mean of the two, √(15,263 × 12,842) = 14,000 Hz, cancels the delay. The tool removes the output latency (getOutputTimestamp) but cannot know your reaction time.
Show Work
Formulas
What Each Test Tells You
Channels. Stereo needs the left signal in the left speaker and the right in the right. Crossed amplifier cables, headphones worn backwards, a “mono audio” accessibility setting, or a single Bluetooth speaker all break that. The channel buttons use the Web Audio StereoPannerNode at pan −1 or +1, which by the equal-power law in the specification sends the whole signal to one side.
Polarity. A speaker pushes its cone out for a positive voltage. If one speaker’s + and − wires are swapped, it pulls in while the other pushes out, so bass, which spreads round the room, partly cancels and the centre image smears. The out-of-phase test does that on purpose: right = −left. Pink noise is used because it has equal energy in every octave, so the whole range is tested at once.
Frequency range and hearing. OpenStax College Physics gives normal human hearing as 20 to 20,000 Hz and notes that age-related loss is more severe at higher frequencies. Where the sweep fades depends on your speakers and your ears together, and on the room. A browser cannot play above half its sample rate. For a hearing check with pure tones, use the tone generator linked below.
Surround. The Web Audio API lists channel order as front left, front right, front centre, low frequency (LFE), back left, back right, and then further channels such as side left and right. The page only shows the surround buttons when AudioDestinationNode.maxChannelCount is above 2, which happens when the system output itself is set to 4, 6 or 8 channels.
Volume safety. The U.S. National Institute on Deafness and Other Communication Disorders (NIDCD) says sounds at or below 70 dBA are unlikely to cause hearing loss, while long or repeated exposure at or above 85 dBA can. This page caps its digital level, but only you control the amplifier and system volume.
About This Tool
This speaker test plays short, quiet test sounds to one channel at a time, compares in-phase and out-of-phase sound, sweeps 20 Hz to 20 kHz with the current frequency on screen, plays a steady tone from 20 Hz to 20 kHz, and tests each surround channel when your output has more than two. Show Work gives the gains and frequencies behind each sound.
Nothing plays and no audio engine starts until you press a button; sound stops when you press Stop or Esc, when the test ends, and when you leave the tab. The page uses no microphone and sends nothing anywhere.
Sources: W3C Web Audio API 1.1 (StereoPannerNode panning, channel ordering, AudioDestinationNode, setSinkId); OpenStax College Physics 2e, §17.6 Hearing; NIDCD “Noise-Induced Hearing Loss”; Peterson & Barney (1952) vowel formants for the voice-like signal; Paul Kellet’s pink-noise filter.
Related tools: Microphone Test, Tone Generator & Hearing Test, and Audio Spectrum Analyzer.
Frequently Asked Questions
How do I test if my left and right speakers are correct?
Press Left: only the left speaker (or the left earcup, marked L) should play. Press Right for the other side. If they are swapped, the cables are crossed at the amplifier or the headphones are on backwards; if both play the same, the output is set to mono somewhere in the system or app.
What does the out-of-phase (polarity) test show?
In the out-of-phase test the right speaker gets the inverted signal, so the two cancel where they meet: the sound is vague, seems to come from the sides and has less bass. In phase, the same signal from both speakers forms a solid image in the middle. If your speakers sound better on the out-of-phase test, one speaker’s + and − wires are swapped.
Why can’t I hear the sweep above a certain frequency?
Three things set the limit: your speakers, your ears and the sample rate. OpenStax College Physics gives normal human hearing as 20 to 20,000 Hz, with losses that grow at higher frequencies with age. Small laptop and phone speakers also roll off the deep bass. Run the sweep rising and falling: if the true limit is 14,000 Hz and you react in 0.25 s, a 20 s sweep gives marks near 15,263 and 12,842 Hz, and their geometric mean is 14,000 Hz.
Is the speaker test safe for my ears and speakers?
The page plays nothing until you press a button, starts at −36 dBFS and cannot exceed −18 dBFS RMS. But your system volume decides the real loudness, so turn it down before the sweep and high tones. NIDCD warns that long or repeated exposure at or above 85 dBA can cause hearing loss, and full-power high tones can damage tweeters.
How do I test 5.1 or 7.1 surround speakers?
Set your system output to 5.1 or 7.1 first, then press any test button. If the browser reports more than two channels, a button appears for each one, in the order the Web Audio API defines: front left, front right, centre, LFE (subwoofer), back left, back right, then side left and right for 7.1. If it reports 2, the browser is getting a stereo output and only the stereo tests apply.
Common Use Cases
New speakers or headphones
Confirm L and R in 5 seconds with Alternate: left, right, left, right, 1.3 s apart.
Find a reversed speaker wire
If the out-of-phase sound is the fuller one, swap + and − on one speaker; in phase the two add to +6.02 dB in the middle.
Check bass from small speakers
The 20–200 Hz sweep covers 3.32 octaves in 10 s, about 3 s per octave, so you can see where the bass disappears.
Check a surround setup
With a 5.1 output reporting 6 channels, play each one and check the centre and subwoofer cables are not swapped.
Spot a dead tweeter
The 8–20 kHz sweep plays the treble range alone; if one side goes silent long before the other, that tweeter is suspect.
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