20 Hz test tone: can you hear the bottom of the bass?

According to Wikipedia's Hearing range article, "The commonly stated range of human hearing is 20 to 20,000 Hz." That's the bottom of the range people are said to hear. The generator's whole range spans 9.97 octaves, from this tone up to 20,000 Hz. One cycle lasts 50 ms, and the wave is 56 feet (17.1 meters) long.

Your ears are most sensitive between 2,000 and 5,000 Hz, and sensitivity varies with frequency, as equal-loudness contours show. A low tone is easy to miss at a modest volume. Speakers make it harder still. According to Wikipedia's Subwoofer article, many small multimedia subwoofers are too small to produce deep bass in the typical 20 to 100 Hz range. Phone and laptop speakers are much smaller than a subwoofer, so expect little or nothing from them at this pitch.

On a subwoofer that can reach this low, the tone is often felt in the floor, the furniture or your chest as much as it's heard. A speaker pushed past its limit adds copies of the tone at whole number multiples of its frequency, called harmonics, so a distorted low tone sounds higher and rougher than a clean one. For this tone, the 2nd harmonic is 40 Hz and the 3rd is 60 Hz, so those are the pitches to listen for. Loose objects can buzz at low frequencies too, like a shelf, a cabinet door, or a light fixture, so move things around and see whether the sound changes.

Volume is the trap. A 20 Hz tone is hard to hear, which tempts people to turn it up until something happens, and that's how a speaker ends up distorting. Most subwoofer drivers rely on large excursion, meaning the cone travels a long way, and according to Wikipedia's Subwoofer article, excursion at high power levels tends to produce more distortion. So start with the volume low, raise it a little at a time, and stop when the tone turns rough, not when it gets loud.

A quiet or missing 20 Hz tone says more about the speaker, the room and the limits of hearing at this pitch than about the tone. The generator plays a clean sine wave and nothing else, so the tone itself is not the likely problem. This page is a listening check, not a measurement, a hearing test, or a speaker rating. If you can't hear it, try another playback device first.