FFT7.9 - App Store

FFT is a high-resolution audio analysis tool for the iPhone and iPod touch. It uses the Fast Fourier Transform to analyze incoming audio, and displays a very detailed graph of amplitude vs. frequency.

Use this app with the built-in iOS device microphone, or upgrade to our iAudioInterface2 or iTestMic for a complete professional solution.

*** Designed for Acoustical Analysis

This application has been designed for acoustics work, and so the bins have been normalized to octaves, to get a display that will show a flat line for pink noise. You can control both the level of graph smoothing and decay time, to get as much or as little detail as you require.

You can also control the dB resolution of the graph, as well as the frequency range that is displayed.

*** Includes Signal Generator

Included in this app is the engine from our Generator app, which is a low-distortion, artifact-free signal generator. The signal generator appears as a heads-up display when you tap the icon, so you can see the graph while you adjust the generator. Generate sine waves, square waves (within limits), white noise, and pink noise, optionally in psuedo-balanced mode. All waveforms are generated in real time using high-precision algorithms.

*** Cursor Readout

Move your finger across the screen to get a cursor to read out exact dB levels and frequencies.

*** Touch-GUI Controls

Use a vertical pinch-open gesture to expand the dB scale.

Use a horizontal pinch-open gesture to expand the frequency scale.

*** Graph Smoothing

Smooth the graph by octave, 1/3, 1/6, 1/12, or 1/24 octave. Adjust the decay time from 0.5 seconds, for a very fast fluid display, to 8 seconds, or use Peak Hold or Average mode. Average mode is a true equal-weighted average, which can run continuously.

*** Peak Tracking

Turn on Peak Tracking to have FFT automatically find a label the frequency of the highest peak on your graph.

*** Tune the Parameters

Set the FFT size from 4096 to 32k points (depending on iOS device) , or select Equal Points Per Octave mode, for high-resolution analysis, even at low frequencies.

*** Calibration

FFT comes calibrated for the typical iPad, iPod touch, or iPhone microphone, and you can adjust the calibration. Microphone compensation files tailored to each iOS device are automatically applied.

*** Save and Recall

When your analysis is complete, you can save the graph image to your photo roll to include in a report, or export the data in an XLS file.

*** Display Multiple Graphs

Show a recalled graph on the screen in a different color.

*** Difference Mode

Use a stored graph as a baseline that is subtracted from the current graph in real time.

*** RTA or FFT?

If you are wondering if you should download this app or our FFT app, check out our website, we have a page devoted to this topic.

*** Other Audio Apps

Also, check out our other great audio and acoustics apps: AudioTools, our premier suite of audio and acoustics analysis apps, SPL, SPL Graph, for recording SPL over time, RTA, RT60, Generator, and Speaker Pop.

Version History -Bug fixes and stability improvements
-Updated for latest iOS and devices 7.9 Sep 11 -Fixed a possible crash on launch 7.8 12/27/2025 -Bug fixes and stability improvements 7.7 12/22/2025 -Updated for new iOS devices
-Bug fixes and stability improvements 7.6 11/24/2025 -Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements 7.5 11/24/2024 -Updated for latest devices and iOS versions
-Bug fixes and stability improvements 7.4 10/17/2024 -Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements 7.3 07/10/2024 -Updated for latest iOS devices and new iOS versions
-Bug fixes and stability improvements 7.2 10/19/2023 -Bug fixes and improvements
-Support for more iOS devices and iOS versions 7.1 07/13/2022 -Bug fixes and stability improvements
-Updated for latest iOS and devices 7.0 09/25/2021 -Bug fixes and stability improvements
-Added user registration feature 6.9 04/02/2021 -Bug fixes and improvements 6.8 02/04/2021 -Bug fixes and stability improvements
-Support for direct data file access in Files app
-Support for latest devices and iOS versions 6.7 08/22/2020 -Bug fixes and stability improvements 6.6 11/15/2019 -Updated for iOS 13
-Bug fixes and compatibility improvements 6.5 10/09/2019 -Updated with latest iOS devices
-Updated for any iOS 9 or later
-Fixed issue with setup menu
-Bug fixes and stability improvements 6.4 08/13/2019 -Updated for latest iOS devices
-Bug fixes and stability improvements 6.3 04/09/2019 -Added compatibility for the latest iOS and new devices.
-Bug fixes and stability improvements. 6.2 09/14/2018 FFT
- Fixed instability in EPPO mode with octave smoothing on iPad Pro 10.5
- Fixed losing EPPO mode recall in some cases
- Added support for iPhone X and other new iOS devices
- Added support for latest iOS 11 6.1 06/08/2018 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

FFT
- Added option to set the plot crossover point to 400Hz, 1kHz, or 2kHz for Normalize mode
- Fixed possible crash when loading older FFT files 6.0 09/25/2017 -Bug fixes and stability improvements 5.9 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. 5.8 03/17/2017 - Updated for iOS 10 and new devices 5.7 11/21/2016 - Updated to support iPhone 7 and iPhone 7 Plus. 5.6 09/24/2016 FFT -- Professional FFT audio 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. 5.5 04/29/2016