# Audio / Spectrum Analyzer — RTA (FFT / Spectrogram)

> Real-time audio analysis with waveform and spectrum display. (iPhone/iPad app by Loop-Sessions.LLC..)

- Source: https://appshunter.io/ios/app/audio-spectrum-analyzer/id1508848574 (this page in markdown: same URL + `.md`)
- Developer: [Loop-Sessions.LLC.](https://appshunter.io/developer/414215366)
- Category: Music, Utilities
- Price: Free with in-app purchases (on sale, was $10.99)
- Rating: 4.60/5 from 1,013 App Store ratings · 97 written reviews indexed
- Age rating: 4+
- Requires: iOS 17.0 · 5 MB
- Languages: American English, Japanese
- Released: 2020-05-18
- Data updated: 2026-08-27
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/audio-spectrum-analyzer/id1508848574/reviews.md

## What is Audio / Spectrum Analyzer?

This RTA app supports simultaneous display of "Audio Waveform", as well as the FFT-based "Amplitude Spectrum" (frequency magnitude) and "Spectrogram" (frequency distribution over time), for audio signals input from a microphone.
(FFT: Fast Fourier Transform, RTA: Real Time Analyzer)

[Features]
- Supports simultaneous display of Waveform / Spectrum / Spectrogram.
- Supports orientation both portrait and landscape.
- Selectable configuration of Waveform / Spectrum / Spectrogram display.
- Selectable FFT size.
- Selectable Window function.
- Selectable Spectrum average.
- Selectable Frequency weighting. (Flat, dBA, dBC)
- Selectable the type of expressing the X direction (frequency) of Spectrum / Spectrogram. (Linear, Log)
- Displays the peak level and its frequency of the spectrum.
- Peak Hold (displays the results of holding past peak values ​​of the spectrum).
- Octave Analysis (displays the spectrum divided into octave bands).
- Generates the audio signal (Sine, Triangle, Squire, Saw)
- Generates the noise signal (white noise, pink noise)
- Pitch meter display.

The Pro version offers Ad-Free Viewing and High-Resolution Analysis (FFT size: 16384, Spectrum Average: 4, 8).

[Setting items]
1. Screen structure :
Select the display screen configuration.
View Num : 1, 2
View Type :
- 1 screen : Wave (Waveform) / 1D (Spectrum) / 2D (Spectrogram)
- 2 screens : W+1D (Waveform + Spectrum) / W+2D (Waveform + Spectrogram) / 1D+2D (Spectrum + Spectrogram)
Layout : Vertical (displayed vertically), Horizon (displayed horizontally)

2. Frequency Axis Scale Type :
Selectable the type of expressing the X direction (frequency) of Spectrum / Spectrogram.
- Linear: Distributed at equal intervals
- Log: The intervals increase logarithmically

3. FFT size :
Selectable FFT size. (number of samples used when performing FFT)
1024, 2048, 4096, 8192, 16384
(* 16384 is available in the Pro version.)

4. Window function :
Selectable window function (multiplication just before FFT) used for spectrum calculation.
Hanning, Hamming, Blackman, No window

5. Spectrum Average
Number of spectrum average for a display of spectrum.
1, 2, 4, 8 (init value: 1)
(* 4 and 8 are available in the Pro version.)
Higher value will make the spectrum less noisy and more smooth, at the cost of lower time resolution.

6. Frequency Weighting :
Selectable frequency weighting.
- Flat: No frequency weighting is applied.
- dB(A): Frequency response that takes into account human hearing.
- dB(C): Relatively flat response.

7. Peak Hold :
Displays the results of holding the past maximum values ​​(peak values) of the spectrum.

8. Octave Analysis :
Displays the results of classifying the spectrum into octave bands.
Division method:
- FFT: Spectral display
- 1/12, 1/6, 1/3, 1 octave: Display divided into octave bands
Calc method:
- Max: Displays the maximum spectrum value in each band
- Average: Displays the average spectrum value in each band

9. Generates the audio signal :
Set the audio signal to be generated.
- There are 4 types of waveform. (Sine, Triangle, Squire, Saw)
- It can set the value of the frequency in 20Hz - 20000Hz.

10. Generates the noise signal :
Set the noise signal to be generated.
- There are 2 types of noise. (White noise, pink noise)

[Other]
- Background color: Black, White
- WaveForm: Line Color (Green, Yellow, Invert), Line Width (1.0 ~ 6.0 px)
- Spectrum: Bar color (Green, Yellow, Color patterns)
- Spectrogram: Colormap, Display range (-150 ~ -60 dB), Display time (4 ~ 15 sec)
- Bluetooth connection policy selection (disabled, HFP, A2DP).
- Scaling of Waveform / Spectrum display in the Y direction (magnification: 0.5 - 2.0).
- Scaling of Spectrum / Spectrogram display in the X direction (magnification: 1.0 - 16.0).

[Information]
- The vertical line spacing in the waveform display is 2 mSec.
- The calculation of spectrum and spectrogram uses the vDSP library.

## Key features

- Simultaneous waveform and spectrum display
- Configurable display layouts
- Selectable FFT size and averaging
- Frequency weighting options (Flat, dBA, dBC)
- Octave band analysis
- Audio signal and noise generation
- Peak hold and pitch meter

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Pro (Remove ads, High-Res analysis) | $11.49 | one-time |


## What do users think of Audio / Spectrum Analyzer?

Overall sentiment: mixed

**Pros**

- 👍 Customizable features
- ⚙️ Accurate measurements
- 🚀 Helpful for troubleshooting
- 💡 Useful for ghost hunting

**Cons**

- 🐛 Crashes and freezes
- 🔋 High battery and CPU usage
- 🚫 Inappropriate ads/content
- 🔒 Security concerns with payment info

**Commonly reported bugs**

- Stuck on latest measurement
- White noise instead of expected functionality
- Disconnects AirPods

**Most requested features**

- Sampling rate adjustment
- Wave shape tracking
- Audio file analysis
- Octave analysis

## Recent user reviews (10 of 97)

All indexed reviews: https://appshunter.io/ios/app/audio-spectrum-analyzer/id1508848574/reviews.md

### 4/5 — Works flawlessly! But…

*2026-08-25*

…and the full paid version just needs one little tweak by the developers: if you could add one or two steps of higher resolution (32768, 65536) to get the lowest frequencies more accurate measured and displayed. Then this App could be used also to identify and locate standing waves pressure maxima more precise (higher latency due the higher sampling is not too relevant in this specific use-case).
Thank you for your work!

### 4/5 — Frequency picking from spectra

*2026-08-18*

Please add the ability to click on a point in the spectrum to see the frequency

**Developer response:** Thank you for your comment.
In the latest version, we have added a feature that allows users to tap on the spectrum to display the frequency at that location. 
Please check it out.

### 5/5 — Muito bom

*2026-06-20*

Jean curtinovi

### 5/5 — The best!

*2026-06-19*

The best !!

### 5/5 — Cool

*2026-06-16*

I don’t know about the other reviews from other people, but I think this is fine

### 5/5 — 耳鳴り

*2026-06-12*

耳鳴りの音に同期できる電子音を探していました。専門家ではないので何を触ったらどうなるとかはわからないけど色々触ってみています。同じ周波数なのに左耳と右耳では聞こえ方が違うということを発見しました。個人的には興味深いアプリだと思います。
バックグラウンドで聴けるようになると尚嬉しいです。

### 1/5 — Not reading frequency

*2026-06-12*

This does not read frequency like ai said and the app

**Developer response:** Thank you for your comment.
This app shows a frequency spectrum and also detects pitch (fundamental frequency).
If it felt like no frequencies were shown, what kind of sound were you testing with?

### 1/5 — Lost functionality

*2026-05-07*

Spectral analysis no longer available. App has worse interface and less information.

**Developer response:** Thank you for your comment.
This app is designed to be easy to use.
Please explain the specific points that concern you.

### 5/5 — เสปรคตั้ม

*2026-04-25, version 2.2.2*

ดีมากก

### 5/5 — App non funzionante

*2026-04-22, version 2.2.2*

Collegando il cellulare all’amplificatore viene disattivato il microfono e quindi l’analisi di spettro non può avvenire.
È obbligatorio collegare il cellulare all’amplificatore che comanda il diffusore da controllare, per alimentare il diffusore acustico con il vostro emettitore di frequenze.
Ho aggiornato l’app alla versione 2.2.2 ho testato il nuovo selettore che avete aggiunto ma purtroppo non funziona, sia dettato alto che basso, appena si innesta il cavo usb-c il microfono del iPhone si scollega, lo si vede chiaramente dalla vostra analisi di spettro che diventa insensibile a qualunque suono o rumore.
Problema risolto, era la configurazione del microfono iPhone a disabilitarlo all’inserimento del cavo usb-c.
Adesso la vostra app funziona.

## Frequently asked questions about Audio / Spectrum Analyzer

### What does this audio spectrum analyzer app do?

This app analyzes audio signals from your device's microphone and displays both the audio waveform and its amplitude spectrum in real-time. It uses FFT (Fast Fourier Transform) to calculate the spectrum, allowing for detailed frequency analysis.

### What are the key features of this RTA app?

Key features include simultaneous waveform and spectrum display, selectable FFT sizes, spectrum averaging for smoother results, various frequency weighting options (Flat, dBA, dBC), octave band analysis, and the ability to generate sine, triangle, square, and saw waveforms, as well as white and pink noise.

### Is this app free to use?

The app is free to download and use, but it does contain in-app purchases. This suggests that some advanced features or customization options may require a purchase.

### What devices is this app compatible with?

The app description does not specify exact compatibility requirements, but it is designed for mobile devices. It supports both portrait and landscape orientations, indicating adaptability to different screen sizes and device types.

### How can I use this app for audio analysis?

You can use this app to visualize the frequency content of any sound captured by your microphone. It's useful for tuning instruments, checking room acoustics, troubleshooting audio equipment, or simply understanding the spectral composition of sounds.

## Version history (last 5 releases)

### 2.5.0 — 2026-08-24

Added a feature that displays the frequency at the tapped position in the spectrum view.

### 2.4.4 — 2026-08-11

Improved spectrum display rendering.

### 2.4.3 — 2026-07-20

- Added an [Audio Processing] setting under [Audio I/O].
[Standard]: Uses standard iOS audio processing. Input levels may be adjusted automatically. (AVAudioSessionModeDefault)
[Measurement]: Minimizes system-supplied signal processing for audio measurement. Because processing such as automatic gain adjustment is reduced, microphone input levels and signal playback volume may be lower than in [Standard] mode. (AVAudioSessionModeMeasurement)

- Adjusted the text size of the spectrum peak level and frequency display.

### 2.4.2 — 2026-07-14

Fixed an issue where spectrogram color map changes were not applied.

### 2.4.1 — 2026-07-08

Added spectrum bar color options with multiple color patterns to choose from.

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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 2026-08-27.*