Generate Pure Tones at Any Frequency
A tone generator is one of those tools you rarely need — until you suddenly do. Testing whether a speaker channel works. Finding the frequency of an annoying hum. Checking the upper limit of your hearing. Tuning an instrument to a reference pitch. Demonstrating sound physics to a classroom. This generator produces mathematically clean tones from 20 Hz to 20,000 Hz — the full range of human hearing — using your browser's Web Audio oscillator, with a choice of four classic waveforms and precise volume control. It runs entirely on your device and starts instantly.
How to Use It
- Start with the volume low. Pure tones are more piercing than music at the same level — protect your ears and speakers.
- Set a frequency by typing an exact value, dragging the slider, or tapping a preset (100 Hz, 440 Hz, 1 kHz, 10 kHz…).
- Choose a waveform: sine, square, sawtooth or triangle.
- Press Play. Adjust the frequency live — the tone glides smoothly as you change it.
- Press Stop when finished.
The Four Waveforms, Briefly
A sine wave is the purest sound possible — a single frequency with no overtones — and is the right choice for hearing tests and precise reference tones. A square wave adds strong odd harmonics, sounding hollow and buzzy like vintage video games. A sawtooth contains every harmonic and sounds bright and brassy — the foundation of classic synthesizer leads. A triangle sits between sine and square: gently rounded with only faint overtones. Comparing them at the same frequency is a five-second education in what “timbre” actually means.
Practical Frequencies Worth Knowing
- 440 Hz — concert pitch A4, the standard tuning reference for orchestras and guitars.
- 1,000 Hz — the universal test tone of audio engineering and broadcast alignment.
- 20–60 Hz — deep bass; if your speakers produce nothing here, they simply cannot reproduce it (small speakers physically cannot).
- 50 or 60 Hz — electrical mains hum; matching a mystery hum to one of these identifies a grounding problem.
- 8,000–17,000 Hz — the treble range where age-related hearing loss appears first; sweeping upward reveals your personal ceiling.
Sensible Safety and Honest Notes
Two cautions belong in any honest description of a tone generator. First, sustained pure tones at high volume can damage hearing faster than music at the same perceived loudness — keep levels moderate, especially with headphones, and never play maximum-volume tones near children or pets. Second, an informal hearing check here is not an audiogram: your speakers, headphones and room all color the result, and laptop speakers in particular reproduce almost nothing below 200 Hz or above 15 kHz. Treat the results as interesting rather than diagnostic, and see an audiologist for anything that matters medically. Within those limits, this is a genuinely useful instrument: free, instant, precise to the hertz, and running entirely in your browser with nothing installed and nothing transmitted.
For a five-minute crash course in audio, try this sequence: play 440 Hz in sine and memorize the pitch — that is the A every orchestra tunes to. Switch waveforms at the same frequency to hear what harmonics add. Then sweep slowly from 200 Hz to 2,000 Hz and notice where your speakers sound strongest. Finally, sweep upward from 10 kHz until the tone disappears — that is your personal hearing ceiling on this equipment. Few tools teach this much about sound this quickly.
Frequently Asked Questions
Is it safe to test my hearing with this tool?
As an informal experiment, yes — at moderate volume. But speakers and headphones strongly affect what you hear, so this is not a medical test. For real concerns about hearing, consult an audiologist.
Why can’t I hear anything above 15,000 Hz?
Two possible reasons: adult hearing commonly tops out between 12 and 17 kHz (age-related and normal), and many speakers — especially laptop speakers — barely reproduce those frequencies at all. Try good headphones before blaming your ears.
What is the 440 Hz preset for?
That is A4 concert pitch, the international tuning standard. Musicians tune instruments against it; the sine waveform gives the cleanest reference.
Which waveform should I use for testing speakers?
Use sine waves. They contain exactly one frequency, so what you hear (or fail to hear) tells you unambiguously how the speaker handles that frequency. Other waveforms include harmonics that muddy the diagnosis.