What Is a Frequency Generator?
This tool generates a real audio tone at any exact frequency you choose, from 20Hz up to 20kHz - the commonly cited range of human hearing. Every tone is synthesized live using the Web Audio API's oscillator node, playing the precise frequency and waveform you select rather than switching between pre-recorded audio files.
A frequency generator like this is genuinely useful for testing speaker frequency response across the range, checking for rattles or distortion at specific frequencies, tuning instruments, or simply hearing what a given frequency actually sounds like.
How to Use the Frequency Generator
- Lower your device's physical/system volume first. Digital gain starts at 2% and is capped at 8%, but this does not guarantee a safe acoustic loudness.
- Select Steady tone for one frequency or Frequency sweep to move smoothly between a start and end frequency. For a steady tone, enter an exact Hz value, use the logarithmic slider, or choose a preset.
- Choose Sine for a clean reference tone, or Triangle, Square or Sawtooth to explore harmonic-rich waveforms. Pick Both, Left or Right channel if the browser supports stereo panning.
- Set a short auto-stop duration and start with a low digital gain. Press Play to generate a live Web Audio oscillator signal; use Stop audio immediately if anything is uncomfortable.
- While a steady tone plays, you may adjust frequency, waveform or gain smoothly. A sweep follows its selected start/end/duration, then fades out and stops automatically; wait for it to finish before changing sweep settings.
- Review the browser-reported sample rate, requested oscillator settings and elapsed playback time. The waveform drawing is a mathematical illustration—not a recording or measurement of your speaker. Use Export sessions CSV if you want a local record of settings and completed/interrupted playback.
- If sound is missing or distorted, check output-device settings at a comfortable volume. A missing tone is not proof of a hearing or speaker fault. Switching tabs stops playback for safety.
How It Works
This tool creates an OscillatorNode through the Web Audio API, sets its
frequency property to your chosen value in real time, and routes it through a
GainNode for volume control before sending it to your speakers. Because the oscillator
generates the waveform mathematically rather than playing back a recording, the frequency you set is exactly
the frequency being generated - there's no approximation or nearest-match happening.
Understanding What You Hear
- Low frequencies (20–250Hz) - bass range; you may feel these as much as hear them on capable speakers, and they're a good test for subwoofer or bass driver rattle.
- Mid frequencies (250Hz–4kHz) - most speech and everyday sound lives here; most speakers reproduce this range cleanly.
- High frequencies (4kHz–20kHz) - treble range; the very top end (above roughly 15–17kHz) becomes progressively harder for adult ears to hear, which is a normal part of natural hearing change with age, not a flaw in the tool.
- Silence or distortion at a specific frequency on your speakers - can indicate a limited frequency response range or a damaged driver at that specific frequency.
Browser Limitations
What you actually hear depends entirely on your speakers or headphones' real frequency response - this tool generates a mathematically accurate signal, but no consumer speaker reproduces the full 20Hz–20kHz range with equal loudness. Very low and very high frequencies commonly sound quieter even though the generated signal itself is at full, consistent volume for its frequency.
Common Mistakes to Avoid
- Jumping straight to high volume at extreme frequencies - always start low, especially above 8kHz, since perceived sharpness can catch you off guard.
- Testing with headphones at very low frequencies at high volume - sustained deep bass at high volume can be uncomfortable or risk headphone driver damage on some cheaper models.
- Assuming silence at very high frequencies means broken speakers - many people, especially adults, naturally can't hear well above 15–17kHz even on perfectly good speakers.
Frequently Asked Questions
Is the frequency I set exactly what's being generated?
Yes. The oscillator generates the waveform mathematically at the exact frequency value you set, with no approximation involved.
Which waveform should I use for testing?
Sine wave is the standard choice for pure-tone testing since it contains only the fundamental frequency with no additional harmonics, making it the cleanest reference tone.
Can I use this to check my hearing range?
You can, though the dedicated Hearing Range Test is built specifically for that, with a guided sweep and clearer results tracking.
Why can't I hear anything above roughly 17kHz?
This is normal - the upper limit of human hearing naturally decreases with age, and many adults can't hear much above 15–17kHz even with fully healthy hearing and good speakers.
Is any audio or usage data recorded?
No. Tone generation happens entirely within your browser and nothing about your session is saved or transmitted.
Conclusion
Whether you're testing speaker range, checking for distortion at a specific pitch, or just curious what 20kHz sounds like, this generator gives you an exact, adjustable tone on demand. Pair it with the Hearing Range Test for a structured check of your own hearing range specifically.