Hear the Date

What you are listening to

Hear the Date is a headphone instrument whose score is a calendar instant and a point on Earth. The Moon and Sun keep two nearly-fixed carriers; their loudness, the depth of the pulse, and where each body sits in the stereo field all move with distance, phase, and the local sky as if you were standing at that latitude and longitude, facing east. Planets do not add new pitches. They lean on the mix.

Open the lab

Headphones. True stereo. Guests cannot start the audio. A free account gets five minutes per UTC day. Members have no daily cap.

Open Hear the Date → Why the beat is 7.83 Hz

A worked minute

Say you set the place to 51.51°N, 0.13°W — London — and the local clock to a March evening just after sunset. The Sun is already under the western horizon. In this lab that means the solar carrier does not vanish; it drops in elevation gain and sits toward the back of the image because west is behind you. The Moon, if it is up in the southeast, comes in on the right ear and a bit in front. Jupiter, if it is anywhere near opposition, is a quiet side-tone whose pan follows the same east-facing map. None of this is a recording of the sky. It is a mapping: tide-scale accelerations into amplitude, local azimuth into stereo pan, altitude into how present a body is allowed to be.

Change only the longitude, keep the UTC timestamp, and the hour angle rotates. London and Cairo on the same instant are not the same mix. That is the whole point of locking time to a coordinate. A “date” with no place is a fiction the tides do not share.

Carriers that barely move

Ordinary binaural pages on this site let you slide a carrier and a beat. Hear the Date does the opposite. The Moon sits near 223.40 Hz, the Sun near 231.23 Hz, and the difference is 7.83 Hz — the same number people pin on the first Schumann peak. That match is a scale choice, not a claim that the ionosphere is coming out of your headphones. The raw lunisolar tide is microhertz. Multiply by 9.9889×10⁶ and the spring–neap envelope, which in the ocean takes about 14.77 days, shows up as a slow change in how hard the 7.83 Hz pulse bites, not as a new oscillator.

A low drone at 136.10 Hz (the so-called “earth year” pitch some just-intonation tables list) holds the floor so the two carriers have something to rest on. You can ignore the lore around that number. It is a bed, not a thesis.

If you want the beat-frequency definition in isolation, use what is a beat frequency. If you want the tidal derivation with M2 and S2 written out, that is spring–neap as a binaural beat.

Facing east

Azimuth in the lab is the usual astronomical one: 0° north, 90° east, 180° south, 270° west. The listener is assumed to stand at the chosen lat/lon looking due east.

Sky direction	In the headphones
North	Left ear
East	Center, in front
South	Right ear
West	Center, quieter, treated as behind
Below the horizon	Still mapped, but elevation gain collapses

That is a stereo panner plus a front/back gain, not an HRTF. West and east both sit near pan 0; west is the one that loses presence. If you have ever tried to fake “behind” with two speakers you already know the cheat. It is good enough that turning the time wheel across a moonrise actually walks the lunar carrier from below, through the left or right, into the front. The CRT under the orrery prints sun and moon azimuth with a cardinal and a crude ear tag (L / front / R / behind) so you can check the map without guessing.

The longer argument, with hour angle and a London-versus-Tokyo example, lives on hearing the sky from one place.

What the planets are doing

Tidal acceleration scales as 2GMR/d³. At Earth’s surface the Moon dominates. The Sun is the same order, a little weaker. Jupiter at opposition is not in the same conversation — you are looking at something like 2×10⁻⁵ of the lunar tide, and the ice giants are worse. If the lab played those ratios honestly you would never hear a planet. So the weights are compressed with a 0.18 exponent and then aligned a bit toward solar syzygy, which is a musical decision. Jupiter becomes a quiet neighbor of the solar carrier, not a second moon.

Each planet still gets its own oscillator (Mercury 229.86 Hz through Neptune 231.22 Hz) so the layer has color, and each one is panned from the same east-facing sky as the Moon. The “Planet layer” fader is the only mix control that is supposed to feel like a fader. All the way left is Moon and Sun. Sliding right lets the compressed weights into the room. If a body is conjunct the Sun it gets a little more; if it is off in quadrature it sits back. Drag a planet on the orrery and you are not remixing — you are changing the date until that geometry is true.

How to drive it

Set a place. UTC at 0°, 0° is the default. Any lat/lon on Earth is valid; the presets are just faster. “Use my location” asks the browser.
Put the date on the wheel (Day / Month / Year / 18.6 y nodal) or type a local datetime, or drag a body on the orrery. The local clock does not snap to midnight when you leave the Day scale.
Optional: “Contrast with now” keeps a quiet ghost of today’s Moon/Sun under the selected date.
ENGAGE from the brass pill or the lower dock. Headphones. The session dock shows place, phase, 7.83 Hz, and tension. Free accounts also see time left today.

Jump buttons (today, next full, next new, next quarter) are date math, not playback. They used to crackle because the audio graph cancelled and rebuilt ramps on every pointer tick. The current engine eases with setTargetAtTime and throttles applies, so you can spin the month without a square-wave of clicks.

Who can hear it

Account	Hear the Date audio
Guest (no account)	None. The orrery still turns. ENGAGE opens create-account.
Free account	5 minutes per UTC day, counted while the engine is actually playing. Pause does not burn the quota.
Member	No daily cap.

The five minutes are for this lab, not for the rest of the Machine. Console programs, the multifrequency mixer, and the ordinary beat pages keep their own rules. If you hit the cap, the session fades and the member tab opens. Next UTC day the quota resets; we do not try to guess your local midnight.

What this is not

It is not a tide table you should sail on. The ephemeris is a compact Kepler set (JPL-style elements 1800–2050) plus a lunar series good enough for phase and a sky position, not a FORTE numerical model. It is not an astrology app, even though the CRT still prints a sign label — that is ecliptic longitude in 30° bins, a habit of the coordinate, not a reading. It is not Schumann resonance coming through the skull; 7.83 Hz is the scaled beat, and the actual cavity peak wanders with lightning and ionosphere. It is not medical. Tension on the CRT is a number derived from the field we build, not a measurement of you.