Support / AFA

Audio Frequency Analyzer for iPhone


"Audio Frequency Analyzer" is a powerful Real-Time Audio Analyzer (RTA) app for iPhone.

"Audio Frequency Analyzer" uses our proprietary signal processing technology to analyze incoming audio signals and provides a precision frequency response measurement and spectral visualization.

In the frequency range of 20kHz from 20Hz, the response of the measurement frequency can be displayed in the logarithmic FFT scale or 30 split band scale of 1/3 Octave.

"Audio Frequency Analyzer" is available in a variety of applications, such as sound room tuning, speaker settings, audio equipment testing, stage setting measurement, evaluation of sound mixing environment and Investigation of noise environment.

In the latest version, the 1/3 octave band calibration is now available. By adjusting the characteristics according to the external microphone used, high accuracy measurement can be realized.



Please to click the following link to download "Audio Frequency Analyzer" from App StoreTM. It will be open the download page on App StoreTM.

It will move to another site, download from Aplle Store

iPhone is a trademark of Apple Inc., registered in U.S. and other countries. App Store is a service mark of Apple Inc.

Products Information

Version : 5.0
Release date : January 23, 2019 UTC
Size : 0.8 MB
Category : Utilities, Music
Recommendations : Requires iOS 12.1 or later.

Measurement display and input signal

"Audio Frequency Analyzer" measures the input acoustic signals, and displays the frequency spectrum in 30 split bands of 1/3 octave , or in the Logarithmic FFT scale.

Observation frequency range: 20 - 23000Hz
Measurement display
FFT Scale: X-axis - log-scale frequency : 20 - 20000Hz
1/3 Octave Scale: X-axis - Center frequency(Hz): 25, 32, 40,50, 64, 80, 100, 125, 160, 200, 250, 320,
400, 500, 640, 800, 1k, 1.25k, 1.6k, 2k, 2.5k, 3.2k, 4k, 5k, 6.4k, 8k, 10k, 12.5k, 16k, 20k
Measurement display Y-axis - Logarithmic amplitude (Ref-Level: 0dB/1V): Up to +30dB from -130dB


"Audio Frequency Analyzer" has the following features:

Optimized for iPhone, Compact code size.
High performance software design for Real Time Spectrum Audio Analyzing.
FFT: 8192points/frame
Ferquency spectrum response measurement of 1/3 Octave unit, 30 bands. (OCT)
FFT analyzer. (FFT)
Logarithmic amplitude band: 70dB/band-width. minimum
Peak Hold function at 1/3OCT mode. (Hold)
Display Response control (Slow)
Function of Touch-Scroll to adjust visible amplitude ranges.
Return function of the display range. (Scroll reset)
Calibration function at 1/3OCT mode. : Octave band offset setting. Overall offset setting.(Calibrate)
Display measured value of 1/3 oct bands. (Oct val.)
Save/Load function at Octave band offset setting. (Set/Info)
Snapshot of Measurement display. (Snap)
Supports built-in microphone, headset microphone, and external digital audio connection.


"Audio Frequency Analyzer" can be very useful for a variety of applications including:

Frequency characterization evaluation of speakers and headphones
Testing and tuning audio amplifiers, equalizers and many other audio equipments
Stage setting measurement
Evaluation of sound mixing environment
Evaluation of car audio equipments installation
Various acoustic testing, and others

How to use - Top View

At the time of starting this app "Audio Frequency Analyzer", this topview will be displayed. All operations can be carried out in the topview screen.

The access permission to the built-in microphone will be confirmed from the iOS system at the first start-up. Please enable access to the built-in microphone.

Top View

The topview has Measurement Mode(OCT/FFT), Calibration(Calibrate), Measured oct value (Oct val), Peak Hold(Hold), Start/Stop, Display response(Slow), Scroll reset, Snapshot(Snap) and Settings(Set&Info) at right side. In addition, it has the measurement display (TRACE DISPLAY) at left side. By touching scroll the screen up and down direction, you can easily change the display range.

How to use - Trace Display

TRACE DISPLAY is the image monitor that displays the frequency spectrum measurements. The display shows the amplitude on the Y-axis, and the frequency of the 1/3 octave scale or logarithmic FFT scale on the X-axis.

TRACE DISPLAY is visible in the amplitude range of 70dB. By Touch Scroll setting, you can be observed in the amplitude display area that is shifted at +30dB to -130dB. The default position is set to 0dB. By tapping "Scroll reset" button, you can return to the reference level of 0 dB.

Trace Display at 1/3 octave mode

Trace Display at FFT mode

How to use - Start/Stop

"Start/Stop" is a function to control the measurement of Frequency Analyzer. Tap "Start" button to start measurement and tap again to stop. Available to verify the instantaneous measurement results.

How to use - Mode (OCT/FFT)

Measurement function has two measurement modes, 1/3 octave mode (OCT), or, FFT mode (FFT). You can select a measurement mode by tapping either mode. The default is set to 1/3 octave mode.

1/3 octave mode

In 1/3 octave mode, you can measure the energy average value of each frequency band by frequency division in 1/3 octave x 30 bands. You can analyze spectrum in a specific frequency band, not the instantaneous frequency peak. It is suitable for more quantitative spectrum analysis.


FFT mode

In FFT mode, It will perform an instantaneous FFT measurement in all measurement frequency. It can measure the instantaneous frequency peak situations, such as cases where multiple harmonics are generated.


How to use - Hold

"Hold" is a display function that is held the accumulated peak level at 1/3 octave mode. In TRACE DISPLAY, the gain of each band will be displayed maximum value is always retained. In addition, it can not be selected at FFT mode.

How to use - Slow

It is the display response control function. By tapping "Slow" button, Trace Display will be show the measurement image slowly. Tap again, it returns to normal response.

How to use - Scroll reset

When you tap "Scroll reset" button, TRACE DISPLAY will be initialized. Reference level of TRACE DISPLAY returns to 0dB. Please use ”Scroll reset" if you want to initialize the image display immediately or to undo the information display.

How to use - Calibrate

"Calibrate" is a function to set the measurement offset gain. It is effective only when measuring in 1/3 octave mode.

By adjusting the characteristics according to the external microphone used, high accuracy measurement can be realized.

If you tap "Calibrate" button, a setting window that can be set to gain correction value is displayed. The overall level value can be set in the range of -15 dB to +15 dB. Also, the offset value per 1/3 octave can be set independently in the range of -15 dB to +15 dB.

Calibration Overall level setting image

Offset value per 1/3 octave setting image

If you tap "Set/Info" button, the calibration data save settings of the offset value in 1/3 octave band is displayed. It can store two offset data and can also reload stored data. For reference, a sample model data for calibration is prepared, so please use it as necessary.

Set/Info screen

Save offset data of 1/3 octave band (Save)

How to use - Oct val

By tapping the "OCT val" button, the response level for each band is displayed in the 1/3 octave band measurement, so it can assist for calibration adjustment.

Display measured value of 1/3 oct bands

How to use - Snap

"Snap" is a snapshot function to save the measurement result image to the Photos (camera roll). The access permission to Photos will be confirmed from the iOS system at the first snapshot usage. Please enable access to Photos.

Snapshot image in oct mode

Snapshot image in oct mode

How to use - Set/Info

If you tap "Set/Info" button, it will be displayed the calibration data save settings and product information.

In the calibration data save setting, you can save/load two data of the offset value in 1/3 octave band.

If you tap "Support" button , Safari will be started and you can view our support web page.

By tapping "Close" button again, it return to the measurement view.

Set/Info screen


Audio Frequency Analyzer version 5.0 was released on January 23, 2019 UTC.

* Correspond to iOS 12.1, Update of UI design, Improved stability.

Audio Frequency Analyzer version 4.3 was released on May 21, 2018 UTC.

* Correspond to iOS 11.3, Improved stability.

Audio Frequency Analyzer version 4.2 was released on March 14, 2018 UTC.

* Performance improvement.

Audio Frequency Analyzer version 4.1 was released on February 22, 2018 UTC.

* Performance improvement.

Audio Frequency Analyzer version 4.0 was released on January 17, 2018 UTC.

* Correspond to iOS 11.2, Update of UI design, Performance improvement.

* Add the 1/3 octave band calibration function.

Audio Frequency Analyzer version 3.2 was released on March 4, 2016 UTC.

* Correspond to iOS 9.2, Performance improvement.

Audio Frequency Analyzer version 3.1 was released on January 16, 2016 UTC.

* Correspond to iOS 8.4, Update of UI design, Performance improvement.

* Add display response control function.

* Delete Monitor function.

Audio Frequency Analyzer version 3.0 was released on March 5, 2015 UTC.

* Correspond to iOS 8.1, Major Update. Changed UI design design, Performance improvement.

* Add Peak-hold function.

* Add Snapshot function.

Audio Frequency Analyzer version 2.1 was released on July 4, 2014 UTC.

* Add gain calibration function.

* Improved low frequency response.

* Optimized code.

Audio Frequency Analyzer version 2.0 was released on April 20, 2014 UTC.

* Correspond to iOS 7.1, Major Update. Performance improvement

* Changed UI design and App name.

* Add Function of Touch-Scroll to adjust visible amplitude ranges.

fo-Kannon Lite version 1.1 was released on November 27, 2013 UTC.

* Update for iOS 7.0, Redesign of UI, performance improvement

* Adjustment of frequency accuracy, Improvement of sensitivity

fo-Kannon Lite version 1.0 was released on August 31, 2013 UTC.


If you use an external digital audio interface via Lightning or USB interface, iOS device is input from the left channel. Please input of the accoustic signal out of the way to level-over by the gain adjustment carefully.
If the acoustic signal of high level is input from external microphone (via pin jack), iOS devices might be switched to the built-in microphone automatically. It is recommended that you should adjust the microphone gain very carefully.
At the time of the first access to Microphone/Photos after installing the app, you will be asked permission to access them from the iOS. If you did not enable this setting on this time, it can not be access from the app by privacy restrictions of the iOS. Please enable slide switch of the app in the access permission of the iOS setting, "Settings > Privacy > Microphone/Photos".

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Support contact :

Please contact us with the following details if you have any requests or problems.

1. Application name
2. Device model
3. iOS version
4. Country you live
5. Details about your requests or problems.

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