# ListenAid — see what you hear

> see what you hear (iPhone/iPad app by Michael Reisigl.)

- Source: https://appshunter.io/ios/app/listenaid/id6747974662 (this page in markdown: same URL + `.md`)
- Developer: [Michael Reisigl](https://appshunter.io/developer/1823656228)
- Category: Music, Utilities
- Price: $3.99
- Age rating: 4+
- Requires: iOS 17.6 · 5 MB
- Languages: American English
- Released: 2025-06-30
- Data updated: 2026-08-24
- User reviews in markdown: https://appshunter.io/ios/app/listenaid/id6747974662/reviews.md

## What is ListenAid?

ListenAid - intuitive & clean realtime audio spectrum analysis.

ListenAid is an acoustic visualization tool optimized for live sound engineering and system tuning (leveraging transfer functions and multi-resolution processing), delivering maximum performance through Metal and Accelerate hardware acceleration.

Audio Engine & Core DSP
•	Lock-Free Processing (RingBuffer):  non-blocking, zero-dropout audio.
•	Low-Level Math (vDSP): minimal CPU load
•	Real-Time Transfer Function: Live reference vs. live channel division: instantly shows frequency responses differences

5 different Analysis models:
•	STFT: Standard Short-Time Fourier Transform.
•	CWT: Continuous Wavelet Transform for high-frequency time resolution; optimized via integral images.
•	CQT: Constant-Q Transform with variable smoothing.
•	QTAM: Amplitude demodulation in the frequency domain.
•	Multi-Resolution: Concurrent Low, Mid, and High FFT windows for low-end frequency and high-end time resolution.

Metal GPU Rendering
•	Spectrogram is GPU-offloaded; maintains 60 FPS even at massive bin sizes
•	Phase Reassignment: Analyzes frame phase differences, shifts energy to exact sub-bin frequencies to sharpen visual traces
•	Simultaneous FFT Traces: Concurrently plots Live, Reference, and Secondary traces with customizable colors and opacities
•	Dynamic Viewport (ViewportMath): Continuous pan and zoom

Analytical Tools & Precision
•	Sub-Bin Peak Detection: Calculates precise peak frequencies using FFT phase correction or logarithmic-parabolic interpolation
•	Pitch Conversion (FrequencyConverter): translates frequency peaks to notes, showing cent deviations (with adjustable concert pitch)
•	Weighting & Tilt: A- and C-Weighting filters; adjustable display tilt
•	Smoothing & Averaging: Exponential, RMS, LUFS, Leq or Peak Hold averaging; psychoacoustic fractional octave smoothing (1/96 to 1 full octave).

System Tests & Signal Generation
•	Sine Generator: Artifact-free oscillator with amplitude fade envelopes; outputs up to the Nyquist frequency
•	Channel Control (SystemTestManager): Routes the generator or loop player via Normal, Solo L/R, or Phase Invert
•	Loop Playback: Imports and loops custom audio files to test spaces using known reference tracks

Workflow & Connectivity
•	Multipeer Control (MultipeerManager): fully remote-control another instance at the mixing desk (volume, mute, generator, playback)
•	Smart Routing: AudioEngine safely intercepts hardware changes and manages BT profiles
•	Preset System: Instantly save and recall all DSP and UI configurations via slots A, B, and Y.


## Version history (last 5 releases)

### 34 — 2026-08-10

- Sinus-Generator Remote smoothing

### 33 — 2026-07-24

- hidden Gain & Volume Sliders

### 32 — 2026-07-21

- spectrogram improvements (flow, reassignment, blur)

### 29 — 2026-07-12

- LUFSi improvements
- double-tap stability

### 28 — 2026-07-11

- ignores Auto Screen Lock

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| --- | --- | --- | --- |
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| [Music Spectrograph](https://appshunter.io/ios/app/music-spectrograph/id432044946) | 2.5 (4) | $9.99 | Music |
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## Related topics

[fft audio](https://appshunter.io/ios/topics/fft-audio)

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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 2026-08-24.*