How to Play
Phone Theremin turns your screen into a two-zone touch instrument. One hand controls volume, the other controls pitch — just like a real theremin.
Volume
Pitch · Vibrato
The activate button unlocks audio — iOS requires a tap gesture before any sound can play.
Touch anywhere in the left zone to engage the volume control. You won't hear anything yet — your right hand needs to touch the pitch zone too.
Both fingers on screen at the same time — you'll hear the theremin sound immediately. Slide to play.
Like a real theremin — removing the volume hand cuts the sound. Use this for phrasing and note separation.
Playing Tips
The faint horizontal lines mark C3, C4, A4 (440 Hz), and C5. Use them as reference points to find familiar notes.
Rotating to landscape gives your right hand more horizontal space, making vibrato control much smoother.
For that classic theremin sound, let your finger drift gently left and right on the pitch zone rather than staying still.
A real theremin's left hand shapes each note — try moving volume up to swell into a note and back down to fade out.
The app respects your device volume. For full theremin sound, set your iPhone volume to maximum and use the in-app volume zone to shape dynamics.
The A4 marker is your tuning reference. If you're playing along with another instrument, find A4 first and use it to orient your pitch.
Recording Your Performance
Phone Theremin can record up to 30 seconds of audio and save it as a WAV file to your device.
Tap REC in the top-right corner to start recording. The button turns red and a countdown bar appears.
Play your performance. The recording captures everything including reverb — up to 30 seconds.
Tap STOP to finish early, or let the bar reach 30 seconds. Recording stops automatically.
iOS Share Sheet opens automatically. Tap Save to Files to save the WAV to your device, or share it directly to Messages, Mail, or another app.
Recordings are saved as uncompressed WAV files (22 kHz mono). They are not stored on any server — everything stays on your device.
Frequently Asked Questions
Make sure both fingers are on screen at the same time — one in the left (volume) zone and one in the right (pitch) zone. Also check that your device isn't on silent/mute and that the volume is turned up.
This is by design. Phone Theremin silences audio when it goes to the background, the same way a real theremin stops when you step away. Tap ACTIVATE again when you return to the app.
This can happen if your device is low on memory. Try closing other apps and recording again. Also make sure you have free storage space in your Files app.
This may happen if iOS interrupted the recording. Try again — tap REC, play for a few seconds, then tap STOP. The share sheet should appear within a second or two.
Yes — the app supports both portrait and landscape. Landscape gives you more horizontal space in the pitch zone, which makes vibrato control easier.
Yes, completely. No internet connection is required. No data is collected or transmitted.
Phone Theremin requires iOS 16 or later. It has been tested on iPhone SE (2nd gen), iPhone 14, and iPhone 15 Pro.
Contact Support
Get in touch
Have a question or found a bug? Send us an email and we'll get back to you.
gawain.duncan@mac.comWe aim to respond within 2 business days.