40 Hz Tone Generator
A free online tone generator producing a pure 40 Hz signal in your browser. Sub-bass speaker test. Pick a waveform, hit play, and adjust the volume slowly.
What is 40 Hz used for?
40 Hz sits in the deep sub-bass range. Useful for testing whether a subwoofer or full-range speaker can reproduce low fundamentals without distortion.
For sub-bass speaker test, set the volume to roughly 30% before pressing play. 40 Hz can sound deceptively quiet at full volume — always start low to protect your speakers and ears.
How to use it
Press the play button on the preview above to hear 40 Hz immediately. To customize the waveform (sine, square, sawtooth, triangle), tweak the volume curve, or add a second tone for beat-frequency comparison, open the full tone generator. The closest musical pitch to 40 Hz is approximately E♭1 (+49¢).
FAQs
Why does 40 Hz sound different on different speakers?
Speaker frequency response varies dramatically. Small monitors and laptop speakers struggle below about 80 Hz; tweeters distort above 16 kHz on cheaper systems. If 40 Hz sounds quiet, distorted, or buzzy, your hardware is likely the limit — not the tone itself.
Is it safe to listen to 40 Hz?
At reasonable volumes, yes. Sustained exposure to any frequency at high volume can damage your hearing. Always start at 0 volume, ramp up slowly, and don't wear headphones at full volume on this page.
What's the closest musical note to 40 Hz?
40 Hz corresponds to approximately E♭1 (+49¢). For exact tuning, use the chromatic tuner.