WorldTuning

An orchestra tunes up, and never stops. WorldTuning is an endless drone built from the moment before a concert begins: the oboe gives the A, strings and winds drift in slightly out of tune and settle onto it, voices join, and the whole hall hums. Every sound is synthesised on the spot — there are no recordings inside the app — so the performance never repeats.

The screen is the performance itself. Each sound rises from the bottom edge and fades away near the top, the last 45 seconds on screen at once. Left to right is pitch. Colour tells you what is sounding: blue for long tones, green for voices, yellow for short sounds, red for the oboe's A. Each instrument and voice has its own shade, and every stroke swells and thins with its sound.

Touch the picture to send the whole orchestra on a journey. Left to right sets the balance between low and high instruments; bottom to top runs through eight places, quiet at the bottom and busy at the top — Solitude, Stillness, Calm, Vertigo, Tuning, Weighty, Radiant and Rhythm — with the top and bottom joined into a loop. A baton knocks on the podium, a crosshair shows where you are aiming, and when you lift your finger the performance travels there over the Transition time while a circle closes in on the spot. Knock three times to stop or start. The performance can also wander the map on its own, and Randomize moves every setting somewhere new.

Everything that shapes the sound is in the Sound sheet, grouped into five tabs:

- Ensemble — how much the oboe, long tones, short sounds and voices take part, whether the oboe's A comes at random or at a steady interval, and the balance between low and high.
- Pitch — the concert pitch from 415 to 466 Hz, how far the players start out of tune and how quickly they converge, how far up the harmonic series they reach and how much its partials stretch, and the temperament: just, equal, quarter tone, 19 tone, slendro, pelog, gamelan or stretched.
- Time — density, build-up and an optional pulse.
- Motion — slow drifts of pitch and register, breathing density, and waves in which the whole ensemble agrees to tune together.
- Tone — vibrato, the air and grain of breath and voice, how much each instrument keeps its own character, a vowel field that makes the orchestra seem to sing, reverb spaces from a small room to a cathedral, and a limiter.

Choose how the performance ends: cut off, fade out, one by one, let ring, a final accent, high to low or low to high. Send the sound to Bluetooth speakers, AirPlay speakers such as HomePod, or a USB audio interface, and control it from Control Center and the Lock Screen. Record exactly what you hear as a 48 kHz / 24-bit WAV file.

WorldTuning can also listen. With Listening on it hears the sounds around it and tunes its own reference pitch to the pitch it hears, leaving out the sound it is making itself; put two or three devices in a room and they tune to one another. The sound is analysed on this device — nothing is recorded, and nothing is sent. While Listening is on the performance sounds somewhat different, the volume no longer goes all the way down, and AirPlay speakers cannot be chosen. Listening comes with Pro.

Leave it running while you work, read or rest. Background Playback keeps it going when you leave the app, Prevent Auto-Lock keeps the picture awake, and the corner buttons can be hidden while still working where they are. A quick guide is built in.

WorldTuning is free with a banner ad. Pro, a one-time in-app purchase, removes the ad and unlocks every setting and recording. The Sound sheet is fully available without Pro.