If you spend enough time in a place, you will begin to know the patterns of that place - the sun and moon, traffic, tides, smells, faces, sounds. SineClock presents an aural pattern - the interaction of three sets of sine waves - representing the time of day.
SineClock uses three sets of two sine waves. One wave in each set is static, sounding at 200Hz, 300Hz and 450Hz (two stacked perfect 5ths). The other wave in each set is detuned slightly (0-5Hz) based on the time. For the first set, the detuned wave moves from 200Hz to 205Hz and back in one minute. The second one moves from 300Hz to 305Hz and back in one hour. The third moves from 450Hz-455Hz and back in one day.
When two sound waves are tuned very close to each other (let's say within 20Hz), you don't hear two distinct tones - instead you hear a "beating" effect, at a rate determined by the difference in frequency between the two waves. So for the first set of waves, at 0 seconds there will be no beating (200Hz-200Hz = 0Hz), while at 30 seconds there will be beating at 5Hz (205Hz-200Hz = 5Hz). By listening for the beats in each set of waves you can get an idea of where they are in their cycles - and what time it is.