Human hearing bottoms out around 20 Hz, so a 7.83 Hz tone can't be played through any speaker. This generator produces it the three ways that actually work — as a beat between two tones, as a pulse, or as a swell — synthesized live in your browser.
The cavity between the Earth's surface and the ionosphere resonates at a fundamental near 7.83 Hz, with higher modes at roughly 6.5 Hz intervals. These are observed mode centers, not multiples of the fundamental — the real cavity is irregular, so the peaks land low of theory and are broad rather than sharp. All of them drift by a few tenths of a hertz with the day–night cycle, the seasons, and solar activity.
Two sine tones, one per ear, separated by exactly the target frequency — 436.09 Hz / 443.92 Hz. Neither ear receives 7.83 Hz. The beat is assembled in the superior olivary complex — the first stop in the auditory pathway fed by both ears — which is why it collapses the moment you remove one earbud. Stereo headphones required.
A single audible tone gated on and off at the target rate, with a band-limited edge so it clicks less. The rhythm is physically in the audio, so it survives speakers, one earbud, or a phone on the nightstand. The most obvious of the three.
The same single tone, but its volume rises and falls on a smooth sine instead of a hard gate. Gentler than the pulse and still speaker-safe — usually the easiest of the three to leave running for an hour.