🌊

Infrasound Generator

This infrasound generator produces pure 1–20 Hz sub-bass and infrasonic sine tones for subwoofer testing, tactile-bass experiments, and acoustic-research demos. The volume ramps up slowly to protect your cone, and a slow-oscillation display lets you see the signal even when you can’t hear it.

ℹ Can your device even do this? Almost certainly not. A true sub-20 Hz acoustic output is essentially impossible on consumer gear — laptops, phones, earbuds and most speakers simply cannot move enough air this low. You will usually hear nothing, or only audible harmonic distortion or port chuffing — that buzz is not the real tone, it is your speaker straining. Only a capable subwoofer produces genuine output below ~20 Hz, and even then it is felt through the body, not heard as a pitch. This is a tone generator, not a measurement: there is no microphone, and nothing is recorded or uploaded.

⚠ Safety & equipment warning. Below ~20 Hz a driver’s cone must move dramatically further to make sound — excursion roughly quadruples for every octave you go down — so a loud sub-bass tone can over-excurt and physically damage a subwoofer (torn surrounds, broken glue joints, bottomed-out voice coils). Keep the volume LOW; this is why real systems use a subsonic filter near 20 Hz. High-level infrasound exposure can also cause pressure, nausea, fatigue, or disorientation. Stop immediately if your speaker makes flapping, mechanical, or distressed sounds, or if you feel unwell.

Selected 8 Hz

125 ms per cycle

—

Preset frequencies (Hz)

Fine frequency: 8 Hz

Logarithmic across 1–20 Hz, so the deepest end has the most resolution.

Master volume 12%

Pick a frequency, then press Play. Start with the volume LOW.

Audio output is digitally clean down to 1 Hz — but your speaker is the real limit, not the math.

Tactile-bass perception guide

Below ~20 Hz you stop hearing a pitch. The tonal sensation ceases around 20 Hz; from there down, infrasound is sensed (if at all) as pressure and vibration in the chest and body rather than as a note.
It takes a lot of level to feel anything. Body vibration only becomes perceptible roughly 20–40 dB above the hearing threshold, and that threshold is already very high in the infrasonic range — so weak playback feels like nothing at all.
Below ~10 Hz you may perceive single cycles rather than a continuous tone — a slow, pulsing pressure — but again only at very high SPL on a capable subwoofer.
Touch the cone or sit near the sub. Resting a hand lightly near (not on) a working subwoofer is often the only way to confirm a true infrasonic tone is being produced when your ears report silence.

How It Works

This low frequency generator uses your browser’s Web Audio API to synthesise a pure sine tone between 1 and 20 Hz and route it — through a gentle subsonic high-pass guard and a gain stage that controls the volume — to your audio output. That output is whatever your computer or phone drives: built-in speakers, headphones, a soundbar, or a hi-fi/home-theatre system feeding a subwoofer. The tone is the intended sound; there is no microphone and nothing is recorded, measured, or uploaded. The level ramps up slowly (about a second) rather than starting abruptly, because a sudden low-frequency transient acts almost like a DC step and can slam a subwoofer cone past its mechanical limits (Xmax). The slow-oscillation waveform display animates at the real frequency, so you can watch the wave crawl across the screen even when your speakers produce no audible sound at all. If you want to detect rather than generate sub-bass energy, see the infrasound monitor for a live microphone-based spectrum view.

Here is the honest physics. Below about 20 Hz, a driver has to move its cone dramatically further to radiate the same sound — excursion roughly quadruples for every octave down. Tiny laptop, phone, and earbud transducers cannot come close to that displacement, so they produce essentially no acoustic energy in this band; if you hear a buzz, you are almost always hearing audible harmonic distortion or port noise, not the fundamental. Even a good full-range speaker typically rolls off below ~30–40 Hz, and most subwoofers are designed to stop around 20 Hz with a deliberate subsonic filter so they don’t destroy themselves trying to reproduce the impossible. Only a specialised, capable subwoofer makes real output below 20 Hz.

And even when the sound is produced, you mostly won’t hear it. The human hearing threshold rises steeply as frequency falls — from roughly 65 dB SPL at 32 Hz to around 90 dB at 16 Hz and ~100 dB by 10 Hz (Møller & Pedersen, Hearing at Low and Infrasonic Frequencies, 2004) — and the tonal sensation of “a note” fades out around 20 Hz. Below that, infrasound is felt, not heard: a sense of tactile pressure or vibration in the chest and body that only appears at very high sound pressure levels (about 20–40 dB above threshold). Below ~10 Hz you may even perceive individual pressure cycles instead of a continuous tone. So treat this as an educational and experimental deep bass tone generator, not a calibrated acoustic source — what reaches your body depends entirely on your hardware, and silence here is normal, not a fault. To explore the audible bass range just above this, the subwoofer test tones tool covers 20–100 Hz with swept and steady-state tones.

Frequently Asked Questions

I pressed Play and heard nothing — is the tool broken?

Almost certainly not — silence is the normal result below 20 Hz. Laptops, phones, earbuds and most speakers physically cannot move enough air to reproduce sub-20 Hz tones, so they output essentially nothing. The waveform display shows the signal is being generated. To get any real output you need a capable subwoofer, and even then a deep infrasonic tone is felt as body/chest pressure rather than heard as a pitch. If you do hear a buzz on small speakers, that is usually audible harmonic distortion or port noise, not the actual tone.

Can my headphones or laptop speakers play a 5 Hz or 10 Hz infrasound tone?

No. Consumer headphones, earbuds, laptop and phone speakers cannot reproduce true infrasound. Their tiny drivers roll off long before 20 Hz, and producing a sub-20 Hz tone would require cone excursion far beyond what they can manage. Any sound you do hear from them at these settings is distortion (harmonics) created by the speaker struggling, not the genuine low fundamental. Real sub-20 Hz reproduction takes a specialised, capable subwoofer in a proper enclosure.

Why can’t I hear it even on a real subwoofer — only feel it?

Because below about 20 Hz the ear largely stops hearing a pitch. The human hearing threshold rises steeply as frequency drops (roughly 65 dB SPL at 32 Hz up to about 90 dB at 16 Hz and ~100 dB by 10 Hz, per Møller & Pedersen, 2004), and the sensation of a tone ceases around 20 Hz. From there down, infrasound is perceived mostly as pressure and vibration in the chest and body — and only when the level is high (about 20–40 dB above the hearing threshold). Below ~10 Hz you may even perceive individual cycles as a slow pulse rather than a continuous tone. So feeling it rather than hearing it is exactly what should happen.

Can a sub-20 Hz tone damage my subwoofer?

Yes, if it is loud. To make sound at very low frequencies a cone must travel far further — excursion roughly quadruples for every octave down — so a high-level infrasonic tone can push a driver past its mechanical limits (Xmax), tearing surrounds and spiders, breaking glue joints, or bottoming out the voice coil. That is exactly why real systems use a subsonic filter near 20 Hz. Keep the volume low here, let the slow fade-in do its job, and stop at once if the speaker makes flapping, mechanical, or distressed noises.

Is exposure to infrasound safe?

At the modest levels reachable through normal computer audio there is no realistic risk — most gear cannot even produce these frequencies. The cautions apply to genuinely high-level infrasound (the kind from large specialised sources), where exposure has been associated with sensations of pressure, fatigue, nausea, and disorientation, and aural pain only occurs at extreme levels (around 140 dB SPL at 20 Hz). This is an educational and experimental tool, not a medical or clinical device. If you feel unwell, stop. People with ear conditions, or who are pregnant, should be especially cautious with any high-level low-frequency exposure.

Does this measure my subwoofer’s response or output in decibels?

No. This is a tone generator with no microphone, so it produces sound but measures nothing — it cannot report SPL in decibels, a frequency-response curve, or distortion. What (if anything) you hear or feel is your whole playback chain and room combined. For real low-frequency measurements you need a calibrated measurement microphone with software such as REW (Room EQ Wizard), or an SPL meter — and for genuine infrasonic field measurement, a specialised infrasound sensor or microbarometer rather than a regular microphone.

What is a subsonic filter and why do real subwoofers use one?

A subsonic filter (sometimes called an infrasonic filter) is a high-pass filter set around 15–20 Hz that prevents a subwoofer from attempting to reproduce frequencies it was never designed to produce. Without it, deeply ported enclosures can experience massive cone excursion at very low frequencies — the port loses its loading effect below its tuning frequency, leaving the driver almost uncontrolled. The result is damaged surrounds, torn spiders, or a bottomed-out voice coil. This is why most AV receivers and subwoofer amplifiers include a subsonic filter near 20 Hz, and why this generator defaults to a low volume.

How is this different from a standard tone generator or bass frequency generator?

A general-purpose tone generator typically covers the full audible range (20 Hz to 20 kHz) and often additional waveforms. This tool is deliberately limited to 1–20 Hz — the infrasonic and deep sub-bass band where speakers stop making pitched sound and produce tactile vibration instead — and it adds safety features specific to that range: a slow gain ramp (to avoid a DC-like thump that could damage a cone), a low default volume, and a per-frequency perception guide. Think of it as a specialised sub-bass test tone generator rather than a general audio utility.

Is infrasound used in music production or film sound design?

Yes, deliberately and carefully. Film sound designers sometimes add very deep low-frequency content (around 8–16 Hz) to enhance the emotional weight of large-scale scenes — the body-pressure sensation adds unease or awe even when the audience cannot consciously hear it. In music, producers working on experimental electronic music or pipe-organ recordings sometimes extend content into the sub-20 Hz region for the tactile experience in venues with capable systems. Commercial mastering, however, usually high-passes everything below 20–30 Hz to protect consumer speakers and avoid wasted headroom on frequencies that playback systems cannot reproduce.

Related Tools

← All Ultrasonic & Infrasound Tools