Transfer Function5.7 - App Store

Transfer Function is a dual-FFT acoustic analysis app that is used for sound system audio analysis. Since it can operate with music as the signal source, it can be used during a musical performance to monitor and turn the system equalization during the show.

Transfer function includes:

-- Magnitude Graph
-- Phase Graph
-- Coherence Plot
-- Delay Finder
-- Signal Generator

Normally a transfer function requires a two-channel interface, and that is true with this one, also, if you want to use it with program material (music).

However, you can use our Transfer Funciton with the internal iOS microphone, if you can send the pink noise generator output to the sound system input. In this configuration, the internal generator is routed back to the input as the reference channel. You can measure delay, magnitude, and phase using this setup.

When you use Transfer Function with a two-channel audio interface to run, such as the Studio Six Digital iAudioInterface2, then you can also use any audio source as the test signal, including music.

See our website for more information.

Version History -Bug fixes and stability improvements
-Support for latest iOS versions 5.7 Sep 11 -Bug fixes and stability improvements 5.6 12/22/2025 -Updated for new iOS devices
-Bug fixes and stability improvements 5.5 11/24/2025 -Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements 5.4 11/21/2024 -Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements 5.3 07/10/2024 -Updated for latest iOS devices and new iOS versions
-Bug fixes and stability improvements 5.2 10/19/2023 -Bug fixes and improvements
-Support for more iOS devices and iOS versions 5.1 07/13/2022 -Bug fixes and stability improvements
-Updated for latest iOS and devices 5.0 09/24/2021 -Bug fixes and stability improvements
-Added user registration feature 4.2 04/02/2021 -Bug fixes and stability improvements 4.1 02/04/2021 -Bug fixes and stability improvements
-Support for direct data file access in Files app
-Support for latest devices and iOS versions 4.0 08/20/2020 -Updated Transfer Function for iOS 13 compatibility 3.2 10/09/2019 -Updated for iOS 13
-Fixed issue with setup menu
-Bug fixes and stability improvements 3.1 08/12/2019 -Updated for latest iOS devices
-Bug fixes and stability improvements 3.0 04/09/2019 -Updated for latest iOS and devices.
-Bug fixes and stability improvements. 2.9 09/14/2018 General
- Added Calibration Error Report link to support page
- Fixed crash on iOS 11 when saving screenshots
- Fixed crashes on iOS 8 and iOS 9
- Fixed issue with multiple Studio Six Digital apps trying to access our accessories
- Updated App Store in-app purchase accessing and authorization for iOS 11


Live Calibration Updates
- Added cloud-based database for all iOS devices that can be updated in real time
- All devices included
- Includes local default files, in case a device has no internet connectivity
- Different databases for each major iOS version, starting with iOS 10
- New iPhones added to live calibration database 2.8 09/27/2017 -Bug fixes and stability improvements
-Support for newer iOS devices
-Fixed crash on iOS 11 beta 2.7 08/28/2017 * Updated for latest iOS devices.
* Removed support for older iOS versions, now requires iOS 8 minimum.
* Added simultaneous background launch protection to prevent problems in iOS 10 when plugging in iTestMic or iPrecisionMic when more than one Studio Six Digital app is installed. 2.6 03/18/2017 - Updated for iOS 10 and new devices 2.5 11/21/2016 - Updated to support iPhone 7 and iPhone 7 Plus. 2.4 09/26/2016 Transfer Function, dual-channel FFT for iOS

** Bug fixes and calibration improvements 2.3 05/07/2016 Transfer Function -- Professional dual-FFTaudio system analyzer. Class One calculations meet all ANSI and ISO standards for Type 1 Sound Level Meters.

Now supports multi-tasking Slide Over and Split Screen on newer iPads that support this feature.
Calibrations adjusted for all iOS devices. 2.2 04/29/2016 Measure loudspeaker system performance using the internal generator and mic, or an external source with a 2-channel interface.

** Updated for iOS 9.3. New calibrations loaded for all iPads.

** Save/Recall Updates
* New! Auto-save file name options are now available from the Save/Recall screen mini-menu. Tap the icon with 3 lines.
* New! Added auto-save Name List to store frequently-used file names.
* Fixed auto-save sequence numbers resetting after app relaunches.
* Fixed case where files may not be saved when using auto-save immediately after Delete All Files.
* Fixed possible crash if action buttons were tapped with no file name selected.
* Improved auto-save naming.

**Improved referral screen layout.

**Now always uses 24-bit audio mode if iPrecisionMic is present.

**Fixed an issue where internal mic gain could change coming out of the background

** Support Menu
* Fixed Forum page access.
* Fixed "Rate This App" access.
* Fixed access to other Studio Six Digital webpages 2.1 04/12/2016 * Bug fixes and stability improvements
* Added Projects feature to Settings menu, project data can be saved in data files 2.0 02/15/2016 ** Updated all calibrations for iOS 9.1
** Added support for iPad Pro
** Fixed crash on launch on iOS 7 1.9 12/03/2015