# High-Frequency Noise Monitor > Monitors and analyzes inaudible high-frequency noise using spectrograms. (iPhone/iPad app by TOON,LLC.) - Source: https://appshunter.io/ios/app/high-frequency-noise-monitor/id1588823574 (this page in markdown: same URL + `.md`) - Developer: [TOON,LLC](https://appshunter.io/developer/633948723) - Category: Utilities - Price: $6.99 - Rating: 3.30/5 from 4 App Store ratings · 2 written reviews indexed - Age rating: 4+ - Requires: iOS 26.2 · 1 MB - Languages: American English - Released: 2021-10-07 - Data updated: 2026-09-09 - Monetization: paid - User reviews in markdown: https://appshunter.io/ios/app/high-frequency-noise-monitor/id1588823574/reviews.md ## What is High? "High-Frequency Noise Monitor" is a noise analysis tool that specializes in high-frequency bands above 8 kHz. You may be exposed to artificial high-frequency noise on a daily basis that is inaudible to the human ear. This app allows you to monitor these noises and examine their occurrence. Generally, noise contains relatively high-frequency components depending on its source, which is classified as high-frequency noise. For instance, harmonic noise radiates from electronic devices' main bodies or power lines of power conversion devices, such as AC-DC power adapters. Depending on its power level, this noise may affect peripheral devices. Some devices generate high-frequency noise to drive away vermin, such as rats and weasels. The frequency of the sound varies depending on the type of vermin. Some devices incorporate sensors that change the volume and frequency over time. When such devices are installed nearby, they can sometimes cause noise problems that have adverse effects on human health. High-frequency noise does not often occur at a constant volume or frequency, but rather in cycles or randomly. Such noise is not easy to detect. This app collects randomly fluctuating high-frequency noise from the iPhone's built-in microphone and performs a frequency analysis. It also retains PCM data from the 20 seconds just before measurement stop, enabling the display of spectrograms for FFT and octave band analysis. A spectrogram is a graph showing the results of a frequency spectrum analysis, with time on the vertical axis, frequency on the horizontal axis, and signal strength represented by colors. With this app, you can visually monitor the occurrence of high-frequency noise. Features: # Main: Real-time frequency analysis function. - Real-time measurement: Automatically stops after a maximum of approximately 180 seconds. - Maximum frequency detection and power level display (dB unit in 20 μPa standard) - Time trace display: approx. 10 seconds - Display gain adjustment (Range): 3 levels (0dB - 90dB / -10dB - 80dB / -20dB - 70dB) # Analysis: FFT/octave band spectrogram analysis function (PCM data for 20 seconds immediately before the measurement is stopped is saved, and spectrogram analysis is performed.) - FFT spectrogram analysis (FFT) - Octave spectrogram analysis (OCT) - Display gain switching (Range): 3 levels - Playback function: approx. 20 seconds. - Playback sound filter (Filter): 8kHz high-pass filter to cut off low-mid range sound. # Snapshot (Snap): Save the analysis result as an image file. Operation Procedure: 1) Sound measurement and real-time frequency analysis (Main) Tap Start button in Main mode to start measurement. It displays the real-time instantaneous frequency analysis result and the trace of frequency time variation. The frequency and signal level at which the maximum level is detected can be displayed numerically. 2) Spectrogram analysis (Analysis) After measurement in Main mode, tap the Analysis button to perform spectrogram analysis. Tap FFT or OCT button to display the spectrogram by FFT or octave band analysis. Notes: - The measurement of high frequency sounds depends on the sensitivity characteristics of the built-in microphone, so it may vary depending on the iPhone model. - Wireless (Bluetooth) headphones and headset are not supported. - At the time of the first access to Microphone and Photos after installing the app, you will be asked authorization to access them by the iOS system. If you have not enabled this setting, the app cannot access them by privacy restrictions of the iOS system. Please enable the access permission on the iOS setting, "Settings > Privacy & Security > Photos or Microphone". Please visit our iOS app support page for more information on this app. ## Key features - Real-time frequency analysis - Spectrogram analysis (FFT/Octave) - Maximum frequency and power level detection - Time trace display - Playback with high-pass filter - Save analysis results as images ## Chart rankings - #199 in Top Paid · Utilities (US App Store) ## Recent user reviews (2 of 2) All indexed reviews: https://appshunter.io/ios/app/high-frequency-noise-monitor/id1588823574/reviews.md ### 5/5 — No customers… *2026-04-01* Every time you update this app, you throw away 1000’s of potential customers. Not all people will update their phones to the latest iOS. I don’t, and I won’t be updating again. Ever. Many can’t update, but don’t need a new phone, or can’t afford to. The app looks no different, so only supporting the latest iOS is not necessary, surely?? Anyway… it’s a good app. It works well, and I like it. But I suppose this is the last update I will receive. Not a big problem I think. Thank you. ### 1/5 — Difficult to use *2025-09-29* Instructions very brief making the app useless to the average individual trying to verify if there is a a source of high frequency noise. (Ruling out tinnitus vs high frequency noise in the home). **Developer response:** This app is designed to monitor the frequency components of high-frequency sounds in real time. For simply detecting high-frequency noises, we recommend our “Mosquitone Detector” app. It can detect and visualize high-frequency noises. Additionally, it features a search mode that can display the direction of the high-frequency sound source that detected the highest sound level on the radar display (pie chart). ## Frequently asked questions about High ### What is High-Frequency Noise Monitor? High-Frequency Noise Monitor is a utility app designed to detect and analyze sounds with frequencies above 8 kHz, which are typically inaudible to humans. It provides real-time analysis and detailed spectrograms to visualize these noises. ### How does High-Frequency Noise Monitor work? The app uses the iPhone's microphone to capture sound, then performs real-time frequency analysis. It can also save PCM data to generate FFT and octave band spectrograms for detailed examination of noise occurrences. ### What devices does High-Frequency Noise Monitor support? High-Frequency Noise Monitor is currently supported on iPhone devices. ### What is the price of High-Frequency Noise Monitor? High-Frequency Noise Monitor is available for a one-time purchase of $5.99. ### How often is High-Frequency Noise Monitor updated? The app was last updated on March 10, 2026, indicating a recent update. The latest version is 6.0. ### What is the age rating for High-Frequency Noise Monitor? High-Frequency Noise Monitor has an age rating of 4+, making it suitable for a wide range of users. ### Does High-Frequency Noise Monitor have ads? No, High-Frequency Noise Monitor does not contain advertisements. It is a paid application. ### What is the user sentiment for High-Frequency Noise Monitor? Based on available data, High-Frequency Noise Monitor has a rating of 3.3 stars from 4 ratings. This suggests a mixed to positive user reception. ## Version history (last 5 releases) ### 6.1 — 2026-08-13 - Improved internal processing and performance. ### 6.0 — 2026-03-10 - Improved internal processing and performance. - Requires iOS 26.2 or later. ### 5.0.1 — 2025-12-22 - Improved internal processing and performance. - Requires iOS 18.7 or later. ### 5.0 — 2024-12-15 - Renewed UI design. - Requires iOS 18.1 or later. ### 4.0 — 2023-10-11 - Improved internal processing and performance. - Requires iOS 16.6 or later. ## Apps similar to High | App | Rating | Price | Category | | --- | --- | --- | --- | | [Decibel X:dB Sound Level Meter](https://appshunter.io/ios/app/decibel-xdb-sound-level-meter/id448155923) | 4.6 (161,260) | Free | Utilities | | [Decibel X PRO: dBA Noise Meter](https://appshunter.io/ios/app/decibel-x-pro-dba-noise-meter/id1257651611) | 4.7 (6,897) | $69.99 | Utilities | | [Noise Guru: Decibel Meter](https://appshunter.io/ios/app/noise-guru-decibel-meter/id6444836813) | 4.6 (299) | Free | Utilities | | [Decibel : dB sound level meter](https://appshunter.io/ios/app/decibel-db-sound-level-meter/id1227650795) | 4.6 (36,118) | Free | Utilities | | [Decibel Meter - Sound Analyzer](https://appshunter.io/ios/app/decibel-meter-sound-analyzer/id1579747105) | 3.5 (54) | Free | Utilities | | [Audio Frequency Analyzer](https://appshunter.io/ios/app/audio-frequency-analyzer/id684641742) | 3.7 (3) | $9.99 | Utilities | ## More apps by TOON,LLC - [Audio Tone Generator Lite](https://appshunter.io/ios/app/audio-tone-generator-lite/id633948720) - [Audio Frequency Analyzer](https://appshunter.io/ios/app/audio-frequency-analyzer/id684641742) - [Sound Level Analyzer Lite](https://appshunter.io/ios/app/sound-level-analyzer-lite/id886090835) - [Sound Level Analyzer](https://appshunter.io/ios/app/sound-level-analyzer/id886109671) - [Hearing Analyzer Portrait](https://appshunter.io/ios/app/hearing-analyzer-portrait/id922806926) - [Hearing Analyzer Lite](https://appshunter.io/ios/app/hearing-analyzer-lite/id922827806) All apps by TOON,LLC: https://appshunter.io/developer/633948723 ## Related topics [noise monitor and analysis](https://appshunter.io/ios/topics/noise-monitor-and-analysis) · [high frequency noise](https://appshunter.io/ios/topics/high-frequency-noise) · [high frequency detector](https://appshunter.io/ios/topics/high-frequency-detector) --- *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 2026-09-09.*