FourThirtyTwo is a native iPhone and iPad app that retunes audio to 432 Hz — or any reference pitch you choose. Import a track, compare the original and retuned sound while it plays, then create a pitch-shifted copy you can keep, save, or share.
Nothing is uploaded. There are no accounts, ads, analytics, or servers behind the app.
ONE PURCHASE. NO SUBSCRIPTIONS
Pay once for the app. There is no subscription and no in-app purchase required to unlock its audio tools.
NATIVE, ON-DEVICE PERFORMANCE
Built for iPhone and iPad with Apple’s native audio and interface frameworks. Processing stays on your device for responsive preview and conversion without an internet connection.
LISTEN BEFORE YOU CONVERT
Flip between original and retuned playback while the track plays. Scrub the waveform, skip around, and decide with your ears before creating a new file.
SOURCE TUNING YOU CONTROL
Each import begins with the standard A = 440 Hz assumption. Run on-device Auto-detect to analyse the recording’s reference pitch, re-run detection whenever you like, or override the source tuning by hand.
ANY REFERENCE PITCH
432 Hz is the default, but the choice is yours: presets for 415 Hz (Baroque), 432 Hz, 440 Hz (ISO standard), 444 Hz, and 528 Hz — or enter any custom frequency from 300 to 600 Hz.
MULTIPLE TRACKS AT ONCE
Batch mode converts a folder or multi-file selection in one pass. Every track has its own source-tuning control, progress, estimate, and clean target-Hz filename.
TRUE PITCH SHIFTING, NOT SPEED CHANGE
Pitch processing keeps timing intact. The result is the same performance at a different reference pitch, without intentionally slowing down or speeding up playback.
YOUR RETUNED LIBRARY
Converted tracks can live in an on-device library with playback, editable titles and artist information, and export controls.
EXPORT YOUR WAY
Save as MP3, M4A AAC, lossless M4A ALAC, FLAC, or WAV to the Files app or through the system share sheet. Supported title, artist, album, comment, and artwork metadata is preserved for MP3 and M4A exports. FLAC and WAV exports contain the converted audio without custom metadata writing.
ACCESSIBLE BY DESIGN
Supports VoiceOver, Voice Control, Larger Text, Dark Interface, sufficient contrast, Differentiate Without Color Alone, and Reduced Motion.
PRIVATE BY ARCHITECTURE
All audio processing happens on your device. The app collects no data. Privacy policy: https://fourthirtytwo.app/privacy.html
GOOD TO KNOW
• Import common audio formats including MP3, M4A/AAC, WAV, AIFF, CAF, and FLAC, up to 500 MB per selected file.
• Import from Files or downloaded, non-DRM tracks in your Music library.
• Apple Music subscription tracks are copy-protected and cannot be retuned. Purchased DRM-free downloads, your own recordings, and ordinary audio files can be imported when iOS exposes a readable local file.
QUESTIONS OR FEEDBACK
support@fourthirtytwo.app
