# Spectral Eye

> Visualizes sound frequencies in a spiral spectrum display. (iPhone/iPad app by Secret Base Design.)

- Source: https://appshunter.io/ios/app/spectral-eye/id546934084 (this page in markdown: same URL + `.md`)
- Developer: [Secret Base Design](https://appshunter.io/developer/413007812)
- Category: Music, Utilities
- Price: Free
- Rating: 4.90/5 from 82 App Store ratings · 56 written reviews indexed
- Age rating: 4+
- Requires: iOS 8.0 · 5 MB
- Languages: American English
- Released: 2012-08-01
- Data updated: 2026-07-04
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/spectral-eye/id546934084/reviews.md

## What is Spectral Eye?

The sound that you hear is made up of vibrations at different frequencies.  Two instruments, such as a guitar or a trumpet, might play the same note -- what makes them sound different are the harmonic frequencies that combine to make the overall tone.

Spectral Eye will reveal these frequencies, so you can see what your sounds are made from.  Using a Fast Fourier transform, incoming sound is split into individual sine waves, which are then displayed on the screen.  Frequency spectrum displays are not uncommon; what makes Spectral
Eye different is the arrangement of the frequencies into a spiral, so that octaves line up as rays coming from the center.

The `concert pitch' of A is a vibration at 440 cycles per second.  One octave above this is a doubling to 880, and an octave below is 220.  On the Spectral Eye display, these frequencies fall into a line.  You can see the structure clearly on the display as you make different kinds of sounds or play music.  The stronger the frequency, the larger the red dot and white line; the size of the dots on the display scale to show the relative
frequency strengths clearly.

When you pluck a string on a guitar, the string will vibrate at a root frequency, but also at a frequency that is twice that of the root, as well as a number of different multiples. The resonant frequencies are what make different guitars sound unique.  Harmonies between the frequencies of multiple notes are what make chords sound interesting.  As the tone
of a synthesizer note changes, you can see different component frequencies rise and fall.

In addition to displaying the frequencies, you can also generate sound using Spectral Eye; we have included a simple synthesizer, which will generate either a pure sine wave, or a sine wave with an additional frequency a fifth above.  Move the control on the right or bottom
part of the screen to change the tone, and touch the main display and move in a clockwise or counterclockwise manner to change the pitch.

The version of Spectral Eye also includes MIDI; you can start a MIDI synthesizer, and then use the Spectral Eye display to trigger notes.  There are dozens of excellent synthesizers available; you can use this app to not only play them, but to see how their sounds are formed. And if you're trying to pick out the notes to a song, you can watch the display to see where the notes land.

Spectral Eye is free, and will remain that way.  No pop-up ads.  No nag screen.  Just good clean fun.  If you like the app, we would very much appreciate a review in the app store.  The core technology in Spectral Eye is part of our polyphonic pitch-to-MIDI app MIDImorphosis, which will let you use an ordinary guitar or other instrument to control MIDI synthesizers.  This technology is also part of Infinite Looper, our innovative MIDI looping app.  We have a number of other music-related apps available; we hope you dig Spectral Eye, and if you want to help us keep good things going, reviews or purchases of our other apps would be awesome!

## Key features

- Spiral frequency spectrum display
- Fast Fourier transform analysis
- Visualizes harmonic frequencies
- Adjustable synthesizer with sine waves
- MIDI input for triggering notes
- Displays relative frequency strengths

## Recent user reviews (10 of 56)

All indexed reviews: https://appshunter.io/ios/app/spectral-eye/id546934084/reviews.md

### 5/5 — Best app ever

*2026-04-11, version 2.0*

This is my favorite app of all time. If it goes away I’m gonna pay someone to build a similar app for me.

### 5/5 — Great for drums

*2026-02-15, version 2.0*

This is the most reliable and accurate tuner I've found so far. I mainly use it to identify the pitch of drums and cowbells. I love it.

### 5/5 — Too bad, it’s so good

*2026-02-10, version 2.0*

A really great app but not updated in years and hasn’t flushed out its potential. Nonetheless, an excellent tool. One of my only negative remarks is that one can’t use 432hz as pitch tuning rather than “concert” 440hz.

### 1/5 — Is it working??

*2025-08-20, version 2.0*

Not for me…

### 5/5 — Extraordinary !

*2025-01-19, version 2.0*

… Meant in the nicest possible way:

This App is innovative, amusing, and useful

Thank You for making it, and for giving it free

### 1/5 — Was great but no update so microphone stays on 24/7/365

*2024-02-29, version 2.0*

This app used to be great but now it does not present a choice to use the microphone only when the app is active. You have to turn the mic on in the iPhone Settings Spectral Eye app settings to get it to work. There is no option in the app to only let the app use the mic when the app is open. If you close the app the app still keeps the microphone connected, until you go back to iPhone Settings Spectral Eye app settings to manually turn the microphone off. The multistep process takes all the fun out of it, and the microphone staying on after you close the app seems creepy. Sorry to complain but this app should be pulled from the store if development and updates are dead. Thank you.

### 5/5 — Thank you, this is wonderfull

*2023-11-29, version 2.0*

I am writing this review because they made this app free to use and thus free to enjoy. Its like a part of humanity in us that just wants to share the joy like a celebration of life. Thank you, I love science and sound is amazing, not prticularly for hearing it but that sound is ripples of pressure through the air, higher frequencies make closer ripples, low base makes long ripples, louder sounds increase the pressure, quiter is less pressure. So you can scientifically create the pressure and size within the air, but one really cool thing you can do with these pressure ripples is reflect them back to their source, and if you get the distance between the source and the reflection surface to be a distance that is a multiple of the width of a ripple then you get what looks like sound standing still, you would need some fog and light to see it, but its called a standing wave and you could place little nurf pelletts in the standing wave and the standing wave will hold them in place, if your reflecting vertically else they will fall but vertical floating balls is what many people like to dramatize the effect by calling it levitation and indeed is entertaining. Its not the toy aspect that is interesting, its the contemplation of what you have actuallly done that would seem impossible, a strip of pressurized air that has no walls yet does not leak. Imagination can lead us to what we could do with that.

I hope you enjoyed my small add-on knowlege.

Thank you Developers!

### 4/5 — The way to sound freedom

*2023-10-14, version 2.0*

Most excellent app and further development from the company worth investing.thank you

### 5/5 — Thank you, thank you, thank you

*2023-10-06, version 2.0*

I’m so glad this app exists. I would buy a device just to have this app on it. Please to not let this app be in the graveyard. 🙏🙏🙏 Thank you, thank you, thank you.

### 5/5 — Eye opening!

*2023-07-31, version 2.0*

Fun to use and interesting to see the relationship between harmonics and primary tones.  Check this one out.

## Frequently asked questions about Spectral Eye

### What does Spectral Eye do?

Spectral Eye analyzes incoming sound and displays its constituent frequencies in a unique spiral spectrum. It uses a Fast Fourier transform to break down sounds into individual sine waves, revealing the harmonic content that defines different instruments and tones.

### How does the spiral display work?

The app arranges frequencies into a spiral where octaves line up as rays emanating from the center. This allows for a clear visualization of musical structure, as frequencies an octave apart will appear on the same line from the center.

### Is Spectral Eye free to use?

Yes, Spectral Eye is completely free to use. The developers have stated it will remain free with no pop-up ads or nag screens, focusing on providing a clean and enjoyable experience for users.

### What are the key features for musicians?

Musicians can use Spectral Eye to see how different instruments produce unique sounds by visualizing their resonant frequencies. It also includes a simple synthesizer and MIDI input, allowing users to generate sounds and control external MIDI synthesizers while observing their frequency composition.

### Can I use Spectral Eye to learn songs?

Yes, you can use Spectral Eye to help pick out the notes to a song. By watching the display as a song plays or as you play an instrument, you can see where the notes land on the frequency spectrum, aiding in transcription and learning.

## Version history (last 5 releases)

### 2.0 — 2017-01-25

This app has been updated by Apple to display the Apple Watch app icon.

MIDI support added.
Updated for iOS 10.

### 1.3 — 2014-01-03

iOS 7 update, and updated Audiobus library.

### 1.2 — 2013-05-01

Introducing support for Audiobus, and a new Theremin sound generator.  Spectral Eye can be placed in the input slot of Audiobus.  A new pro version of the app is also available, which can be placed in any Audiobus slot.  The pro version also has support for MIDI.

### 1.1 — 2013-01-29

The app now supports landscape and portrait modes, and also the iPhone 5.

A new lock control freezes the display, so that you can look closely at the frequency spectrum.

### 1.0 — 2012-08-01

No release notes.

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## More apps by Secret Base Design

- [Apollo MIDI Controller](https://appshunter.io/ios/app/apollo-midi-controller/id720942905)
- [FCBFF](https://appshunter.io/ios/app/fcbff/id896310133)
- [Apollo Sound Injector - Streaming Audio between iOS Devices](https://appshunter.io/ios/app/apollo-sound-injector-streaming-audio-between-ios-devices/id912136793)
- [Infinite Looper](https://appshunter.io/ios/app/infinite-looper/id1054808350)
- [Sidecar MIDI Controller](https://appshunter.io/ios/app/sidecar-midi-controller/id1073305840)

All apps by Secret Base Design: https://appshunter.io/developer/413007812

## Related topics

[spectral eye](https://appshunter.io/ios/topics/spectral-eye) · [secret base design](https://appshunter.io/ios/topics/secret-base-design) · [cymascope](https://appshunter.io/ios/topics/cymascope) · [spectral](https://appshunter.io/ios/topics/spectral) · [spectral analysis](https://appshunter.io/ios/topics/spectral-analysis)

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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 2026-07-04.*