# Transfer Function — Magnitude, Phase, Coherence

> Dual-FFT acoustic analysis app for sound system measurement and equalization. (iPhone/iPad app by Andrew Smith.)

- Source: https://appshunter.io/ios/app/transfer-function/id824037130 (this page in markdown: same URL + `.md`)
- Developer: [Andrew Smith](https://appshunter.io/developer/291822462)
- Category: Music, Utilities
- Price: $49.99 with in-app purchases
- Rating: 3.00/5 from 2 App Store ratings · 2 written reviews indexed
- Age rating: 4+
- Requires: iOS 13.0 · 25 MB
- Languages: American English, European Spanish, German (Germany), Polish, Chinese (Simplified, China), French (France), Swedish, Japanese
- Released: 2014-02-23
- Data updated: 2026-08-14
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/transfer-function/id824037130/reviews.md

## What is Transfer Function?

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.

## Key features

- Dual-FFT acoustic analysis
- Magnitude, Phase, Coherence graphs
- Delay Finder
- Signal Generator
- Music as signal source
- Internal microphone support
- Two-channel audio interface compatibility

## Pricing and in-app purchases

Base price: $49.99.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Reference Curves Option | $14.99 | one-time |


## Recent user reviews (2 of 2)

All indexed reviews: https://appshunter.io/ios/app/transfer-function/id824037130/reviews.md

### 1/5 — Unusable on 5th Gen iPad Air

*2025-01-09*

Jan 8, 2025 - Finally got around to testing out the app. In a controlled environment under a variety of circumstances, program is unable to make reliable delay calculations on an up to date 5th gen iPad Air. Even with a “save photo” feature there is no meaningful way to compare two FFT graphs in-app. Major doubt is also thrown on the accuracy of the results given the wild variance in results on the delay finder. 

I downloaded the app with the hopes of using it to calculate software and hardware latencies, as well as quickly time and phase align PA before shows - I can do neither of these things. Disappointed and would like a refund.

### 1/5 — Not satisfied at all

*2017-11-01*

The Software is very inaccurate when using an external microphone. Not usable at all for me. The UI is Not very intuitive and looks messy. The way traces are stored and recalled is way too complicated. Hope These issues geht fixée in future Updates.

## Frequently asked questions about Transfer Function

### What is Transfer Function used for?

Transfer Function is a dual-FFT acoustic analysis app designed for sound system audio analysis. It helps monitor and adjust system equalization, especially during musical performances.

### Can Transfer Function be used with music?

Yes, Transfer Function can operate with music as the signal source. This allows for real-time monitoring and adjustment of system equalization during live musical performances.

### Does Transfer Function require special hardware?

While it can function with the internal iOS microphone by routing its pink noise generator, Transfer Function is optimized for use with a two-channel audio interface like the Studio Six Digital iAudioInterface2 for full program material analysis.

### What are the main analysis tools in Transfer Function?

The app includes a Magnitude Graph, Phase Graph, Coherence Plot, a Delay Finder, and a Signal Generator for comprehensive acoustic analysis.

### How much does Transfer Function cost?

Transfer Function is a paid application, priced at $49.99. It is available for iPhone, iPad, and iPod.

### What is the update frequency of Transfer Function?

The app was last updated on December 22, 2025, indicating active development. Its latest version is 5.6.

### What is the user sentiment for Transfer Function?

Based on available data, Transfer Function has a rating of 3.0 stars from 2 ratings, suggesting a mixed user reception.

### Is Transfer Function suitable for all ages?

Transfer Function has an age rating of 4+, making it suitable for younger users and adults alike.

## Version history (last 5 releases)

### 5.6 — 2025-12-22

-Bug fixes and stability improvements

### 5.5 — 2025-11-24

-Updated for new iOS devices
-Bug fixes and stability improvements

### 5.4 — 2024-11-21

-Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements

### 5.3 — 2024-07-10

-Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements

### 5.2 — 2023-10-19

-Updated for latest iOS devices and new iOS versions
 -Bug fixes and stability improvements

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| --- | --- | --- | --- |
| [ToneGen PlusMinus](https://appshunter.io/ios/app/tonegen-plusminus/id6758056304) | — | Free | Music |
| [MINIBUS Player](https://appshunter.io/ios/app/minibus-player/id6744452636) | — | Free | Music |
| [D-Remote](https://appshunter.io/ios/app/d-remote/id6745768913) | — | Free | Music |
| [Aune Control](https://appshunter.io/ios/app/aune-control/id6720728546) | — | Free | Music |
| [KORG cortosia](https://appshunter.io/ios/app/korg-cortosia/id952982019) | 4.2 (6) | $9.99 | Music |
| [Open Sound Meter](https://appshunter.io/ios/app/open-sound-meter/id1552933259) | 5.0 (4) | $69.99 | Music |

## More apps by Andrew Smith

- [Speaker Polarity](https://appshunter.io/ios/app/speaker-polarity/id293263027)
- [SPL](https://appshunter.io/ios/app/spl/id293573990)
- [RTA](https://appshunter.io/ios/app/rta/id298839433)
- [FFT](https://appshunter.io/ios/app/fft/id298840058)
- [RT60](https://appshunter.io/ios/app/rt60/id298840320)
- [Generator](https://appshunter.io/ios/app/generator/id298840802)

All apps by Andrew Smith: https://appshunter.io/developer/291822462

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-14.*