Online Tone Generator — Pure Sine Tones from 20 Hz to 15 kHz
This tone generator plays a pure sine wave at any frequency between 20 Hz and 15 kHz, directly in your browser: drag the slider and the pitch follows in 10 Hz steps, with the exact value shown in Hz. Use it to sweep a speaker and hear where the bass gives up, to track down a rattle in a car door, or to find roughly where your own hearing stops. Turn your volume almost all the way down before you press play. The tone is generated locally — nothing is recorded or uploaded.
Read this before you press play
A sustained tone can damage your hearing and your speakers, and both kinds of damage are permanent. Set your system volume near zero, start the tone, then raise the level slowly until you can just hear it. Never press play with headphones already on your head at an unknown volume.
Speakers are at risk because a sine wave is nothing like music. Music spreads energy across the spectrum in short peaks; a tone puts continuous energy into one driver at one frequency. A tweeter may be rated for only a couple of watts, because recordings carry little sustained treble — hold a loud 8–12 kHz tone and you can cook its voice coil in seconds. A loud 20–30 Hz tone instead drives a woofer past its excursion limit. If the sound buzzes or turns rough, turn it down at once.
Your ears are at risk for a quieter reason. Damage depends on level and duration, and a steady tone gives no relief between peaks. High frequencies are the trap — a 13 kHz tone can be genuinely loud while feeling thin, so people turn it up hunting for it. If your ears ring afterwards, stop.
How to use the tone generator
One slider, one button. The slider covers 20 Hz to 15,000 Hz in 10 Hz steps, the readout shows the current frequency, and the button starts and stops a sine wave there. Moving the slider while the tone plays changes the pitch instantly, so the frequency sweep here is done by hand — and slow is what makes it useful. Move a few hundred Hz at a time and pause; a fast drag hides a dip 100 Hz wide.
Frequencies worth knowing
20–60 Hz is sub-bass, felt more than heard, and only a subwoofer or sealed headphones reproduce it. 80–200 Hz is where room modes and panel rattles live. 440 Hz is concert pitch A4; 1 kHz is the standard reference tone in audio specs. Around 3–4 kHz hearing is most sensitive, so tones there sound much louder for the same output. Above 10 kHz is air and sibilance — the first region lost with age. Before sweeping, confirm both channels are alive with the left right speaker test.
What a frequency sweep tells you about your speakers
Roll-off is the main thing to listen for: going downward, the point where the tone stops getting quieter and simply vanishes. Laptop speakers usually produce nothing useful below about 150 Hz and phone speakers nothing below 400–500 Hz, however high you turn the volume. Bookshelf speakers typically give up near 50–60 Hz; headphones go lower than any of them.
- A buzz at one narrow frequency — something mechanical is resonating: loose trim, a grille, a screw, a cabinet panel. Not a speaker fault.
- Distortion across a whole band — the driver itself is struggling or damaged.
- A tone that disappears and returns slightly higher — a room cancellation. Move your head 30 cm and it changes.
- Silence across an entire driver's range — a dead tweeter or woofer, or a crossover fault.
One honest caveat: your ears are not flat. Sensitivity drops steeply at both extremes, so even a linear speaker sounds quieter at 30 Hz than at 1 kHz. A sweep by ear finds faults and roll-off; it does not produce a response curve.
Testing a subwoofer and hunting rattles
For a subwoofer, sweep 20–80 Hz at a moderate level with a hand near the cone or port. Feeling air move at 25 Hz while barely hearing anything is normal. If the cone never moves anywhere in the band, the fault is upstream — cable, gain, crossover setting or a muted LFE channel.
Rattles are what this tool is best at, because one held frequency isolates what music cannot. In a car, most door card, trim and dashboard rattles sit between 50 and 80 Hz, inside a useful range of roughly 30–150 Hz. Sweep until something buzzes, stop there, and leave the tone running while you press your palm on panels one at a time. When the buzz stops under your hand you have found it, and foam tape or a tightened screw usually ends it. Indoors, check light fittings, window frames, cabinet doors and picture frames.
The audible range and how it narrows with age
The textbook range of human hearing is 20 Hz to 20 kHz, but almost no adult reaches the top. High-frequency loss starts in your twenties and works downward: teenagers often reach 17–19 kHz, people in their twenties 16–17 kHz, thirties 15–16 kHz, and by the fifties many hear nothing above 12–14 kHz. Noise exposure speeds it up and none of it comes back. It goes unnoticed for years, because speech sits mostly below 8 kHz.
To find your own ceiling with this online tone generator, set a comfortable level at 1 kHz, then step upward without touching the volume again and note the highest frequency you still detect. The slider stops at 15 kHz, so a young listener hears the top of the range and learns nothing — a limit of the tool, not a result.
A rough self-check, not an audiogram
Consumer headphones plus an uncalibrated browser cannot measure hearing loss. A real audiogram reports the quietest sound you detect at each frequency, in dB HL, using calibrated transducers in a sound-treated booth, one ear at a time. This page plays a fixed-amplitude sine wave into whatever chain your computer has, and browser gain, OS volume, headphone sensitivity and EQ all change the level at your eardrum. Many headphones roll off above 16 kHz, so a tone you cannot hear may never have been produced; Bluetooth codecs discard high frequencies first.
What a browser can show honestly is a gross asymmetry or a hard ceiling — one ear clearly worse than the other at the same setting, or nothing above a frequency your age group normally hears. Either is a reason to see an audiologist, not a diagnosis of anything. For an audio problem rather than a hearing one, the general sound test covers playback and recording together, and the microphone test checks the input side with live playback.
Frequently asked questions
How many Hertz can a human hear by age?
Most adults hear roughly 20 Hz to 15–17 kHz, not the textbook 20 kHz. The ceiling falls steadily with age: teenagers often reach 18–19 kHz, people in their twenties about 17 kHz, and by 50 many hear nothing above 12–14 kHz. Loss always starts at the top and works down, which is why it goes unnoticed for years — speech lives mostly below 8 kHz.
Are online hearing tests accurate?
No — not as a measurement. An audiogram uses calibrated headphones in a sound-treated booth and reports the quietest level you can hear at each frequency in dB HL. A browser has no idea how loud its tone actually is at your eardrum: your volume slider, headphone sensitivity, Bluetooth codec and room noise all change it. Treat this as a rough screen, and if one ear seems worse, book a real test.
Are test tones harmful for speakers and subwoofers?
They can be, at high volume. A sine tone is continuous energy at a single frequency, while music spreads energy across the spectrum in short peaks. A sustained tone above roughly 5 kHz is the classic tweeter killer — tweeters often handle only a couple of watts — and sustained 20–30 Hz pushes a woofer past its excursion limit. At a normal listening level nothing bad happens. Start near silence and stop at the first buzz.
How harmful is listening to those headphone sound quality tests?
Harmful only if you run them loud, but the risk is real. Hearing damage depends on level and duration — around 85 dB is safe for hours, 100 dB for minutes — and a steady tone gives your ears no relief between peaks. High frequencies are the trap: at 12–15 kHz a tone can be genuinely loud while feeling thin, so people turn it up hunting for it. Set the volume before you press play, not after.
How can I test whether I've blown my speakers?
Sweep a tone slowly through each driver's range at low volume and listen to what the sound does. A blown driver is either silent across its whole band or distorts on everything — a scratchy, torn quality that stays no matter the frequency or where you stand. A buzz at one narrow frequency is almost always loose trim instead. Check that both channels are alive first, before blaming a driver.
How do I find a speaker rattle with a tone sweep?
Sweep slowly through 30–150 Hz at moderate volume and stop on the frequency that makes it buzz, then hunt with your hands. Most trim and panel rattles sit between 50 and 80 Hz. Leave the tone running and press on door cards, grilles, light fittings and window frames one at a time — when the buzz stops under your palm, you have found it. Foam tape or a tightened screw usually fixes it.
Why won't my speakers play a 20 Hz tone?
Because most speakers cannot go that low. Laptop and phone speakers usually produce nothing useful below 150–500 Hz, and typical bookshelf speakers stop around 50–60 Hz. Real 20 Hz output needs a large driver and a lot of power, since the wavelength is close to 17 metres. Headphones often manage it because they seal your ear canal and pressurise it. Feeling a 25 Hz tone more than hearing it is normal.