# Low Frequency Detector

> Acoustic measurement tool for detecting and analyzing low-frequency sounds. (iPhone/iPad app by TOON,LLC.)

- Source: https://appshunter.io/ios/app/low-frequency-detector/id1196584147 (this page in markdown: same URL + `.md`)
- Developer: [TOON,LLC](https://appshunter.io/developer/633948723)
- Category: Utilities
- Price: $9.99
- Rating: 2.80/5 from 6 App Store ratings · 8 written reviews indexed
- Age rating: 4+
- Requires: iOS 26.2 · 1 MB
- Languages: American English
- Released: 2017-01-26
- Data updated: 2026-09-04
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/low-frequency-detector/id1196584147/reviews.md

## What is Low Frequency Detector?

"Low Frequency Detector" is an acoustic measurement tool for detecting low-frequency sounds that is hard to hear in normal situation. 

The human ear is not sensitive enough to low-frequency sounds. If you are exposed to noise from nearby construction or factories without realizing it, you may feel discomfort or a sense of pressure. In such cases, you can use this app to check what kind of low-frequency noise is present.

Generally, low-frequency sounds is a sound wave ranging from 1Hz to 100Hz. Depending on its frequency component and sound level, the degree of influence on the human body and the noise sensation is different. 

This app allows you to examine the frequency component of low-frequency sounds by 1/3 octave band analysis and FFT analysis.

Features:
- Low-frequency power level measurement less than 100Hz (LF Level):  Flat characteristic, Updating indication of measurement period 1 sec.
- Power level measurement in the audible band (Leq): Flat characteristic, Updating indication of measurement period 200ms.
- 1/3 octave band analysis (OCT)
- FFT analysis (FFT)
- Time course graph (TIME) 
- Snapshot (Snap) on the measurement display screen.
- Report function (Report): Analysis report of a peak LF Level with TIME, OCT and FFT.
- Measurement time: up to 60 sec

Functions: 
The measurement analysis is performed in the following step. Be sure to set the measurement conditions in Step-1 once before starting the sound measurement.

1) Calibration (Calibrate): The reference signal (1kHz sine wave) is output to determine the reference noise level for the low-frequency component. If the volume level of iPhone is set to about 20-50%, the calibration will automatically adjust it to the optimum volume level for the reference signal.

2) Measurement (Measure): Analyze a power level of low-frequency sounds. 
- LF Level (dB): Low-frequency power level less than 100Hz. 
- Leq (dB): Sound power level with the frequency weight characteristic Z (Flat) of the audible band.

3) Measurement display: It can select either 1/3 octave band frequency analysis, FFT analysis or Time course graph. They are updated in real time.

4) Report: Measurement result report. It is effective when measuring for 10 seconds or more.
# Time course graph: TIME
- Low-frequency (LF) Level (dB): Time course graph with peak level noise level judgment (RED-very noisy, YELLOW-noisy, GREEN-normal) at the peak level.
- LF max (dB): maximum dB value of low frequency.
# Frequency response graph: OCT, FFT
 - OCT Band LF max (dB): maximum dB value in 1/3 octave band at LF max observation.
 - Max Level Frequency (Hz): peak frequency at LF max observation.

Notes:
- The sound measurement of the low-frequency range is a level difference with respect to the reference signal, which indicates the relative power level. 
- The reference signal is output during calibration and sound level measurement.
- Do not change the volume level of iPhone after the calibration. 
- White line in the OCT and FFT modes indicates frequency characteristics in frequency weight correction of G characteristics.
- Since iPhone's built-in microphone has a lower sensitivity on the very low frequency range, it is not recommended to measure a huge volume sound near a very loud noise source.
- Since it takes a while for the observation value to stabilize immediately after the start of measurement, the maximum value is calculated from about 2 seconds later.
- In the case high power of 1kHz component is included in the measured noise source, the precision of measured value by this app largely decreases. 
- Sudden noise or impulsive sounds are not low frequency noises in general.
- The previous calibration information can be maintained internally.
- The analysis results may vary due to individual differences in iPhone devices.
- The authorization to access built-in microphone and Photos will be confirmed by iOS system at first access.

Please visit our iOS app support page for more information.

## Key features

- Low-frequency power level measurement (<100Hz)
- Audible band power level measurement (Leq)
- 1/3 octave band analysis (OCT)
- FFT analysis (FFT)
- Time course graph (TIME)
- Measurement report generation
- Calibration function

## Recent user reviews (8 of 8)

All indexed reviews: https://appshunter.io/ios/app/low-frequency-detector/id1196584147/reviews.md

### 1/5 — Low Frequency Detector

*2024-05-07*

This app will not calibrate

**Developer response:** To ensure proper calibration, please check the following three points.

1) Check that this app has permission to access the iPhone's built-in microphone.

2) Calibration cannot be completed if the iPhone audio output level is too low or too high. Try setting the iPhone audio volume to the appropriate gain (20%-50%).

3) Calibration cannot be performed if the background noise level is very high in your environment. Try the calibration in a quiet place as far as possible.

Please see our app support website for more information on this issue.

http://www.toon-llc.com/support/lfd_en.html

Thank you.

### 1/5 — Rubbish and a scam

*2023-11-11*

Pretty sure I previously wrote a review about this, but it seems to have been removed. This DOES NOT detect low frequency. The frequency response of the iPhone microphone is not sufficient to do so. Aside from that the capability of the phone to provide a low pass filter does not exist. SCAM.

**Developer response:** As you mentioned, the frequency response of the iPhone's built-in microphone is less sensitive below 100 Hz. In this app, we do not use the simple technique you might imagine, such as direct low-pass filtering the iPhone's built-in microphone signal.
This app employs our proprietary digital signal processing technology to detect and analyze only low-frequency components using a specific frequency extraction technology with a reference signal. Therefore, it requires a reference tone output and pre-measurement calibration. It was developed for iPhone devices based on the logical sound analysis technology. Details cannot be disclosed due to our confidential technical information.
Thank you for your understanding.

### 5/5 — Very useful and it works

*2023-01-21*

This app had a slight learning curve, but it’s well designed to lead one through what to do. It’s easily well-calibrated enough for my purposes, and getting it to work with the tiny iPhone mic was ingenious. Extremely worth the value. Update: I realized after I wrote the above that it almost looks like a fake review. I’m a meditator who is very sensitive to sound in the environment. LF sound is hard to localize, but I was able to use this app, in addition to my other senses, to walk around and eventually find many intermittent LF sources in my vicinity, made easier by the multimodal sharp peaks in the FFT when I got closer to and farther from different sources.

### 5/5 — Source of low hum identified

*2022-02-22*

Low sporadic hum seemed to be coming from all directions. App allowed me to pinpoint the room and the source which was next doors bathroom extractor fan coming in via a shared wall.

### 4/5 — Pretty good

*2020-12-15*

This app isn’t as intuitive as other noise detection apps. You have to tune it first by adjusting the volume on your phone, as it sends out a reference signal. The other thing that is not intuitive is it doesn’t show you a live readout of decibels versus frequency like some of the other apps. You have to essentially push “record” and it takes a reading over 60 seconds, then push another button to get the report.

I’m giving it four stars though because it seems pretty accurate. When I’m sensing my neighbor’s bass, it reflects in the report as well (the report shows you the decibels versus frequency and is color-coded to reflect low, medium, or high noise levels), and when I’m not sensing it, it reflects that too.

### 1/5 — Rip off - doesn’t actually work as cannot be ‘tuned’

*2020-10-04*

Don’t waste your money

**Developer response:** In order for this app to work properly, it is necessary to make the microphone access permission settings related to the iOS system. In addition, please check the default settings (tuning and calibration) listed on our support page and try again.

### 4/5 — Works best between 30 Hz and 110 Hz

*2020-04-11*

It cannot detect 120 Hz or above because it is outside the range, and 20 Hz and below seems to get lost in the background noise.  Both 30 Hz and 110 Hz are detected.

### 1/5 — Doesn’t work

*2019-11-03*

This app does not work, no support, hard to contact anyone. Don’t buy it.

**Developer response:** Our web support desk is available. Please check the email address information on our website again.

In addition, there may be a problem accessing the microphone. Please check if you have enabled the microphone input in the iOS settings.

## Frequently asked questions about Low Frequency Detector

### What is the main purpose of Low Frequency Detector?

Low Frequency Detector is designed to measure and analyze low-frequency sounds (1Hz to 100Hz) that are typically inaudible to the human ear. It helps users identify and understand potential noise pollution from sources like construction or factories.

### How does Low Frequency Detector measure sound?

The app uses a calibration step to set a reference noise level, followed by measurement and analysis. It can perform 1/3 octave band analysis (OCT) and FFT analysis to examine the frequency components and power levels of low-frequency sounds.

### Can Low Frequency Detector detect all types of noise?

This app specifically focuses on low-frequency sounds below 100Hz, which are often difficult to perceive. It also measures the overall sound power level in the audible band (Leq).

### What kind of reports does Low Frequency Detector generate?

The app can generate analysis reports that include peak LF Level, time course graphs with noise level judgments (RED-very noisy, YELLOW-noisy, GREEN-normal), and frequency response graphs (OCT, FFT) showing maximum dB values and peak frequencies.

### Is Low Frequency Detector available on multiple devices?

Based on the provided data, Low Frequency Detector is currently supported on iPhones.

### How often is Low Frequency Detector updated?

The app's latest version is 8.0, and it was last updated on February 16, 2026. This indicates a recent update, suggesting ongoing development and support.

### What is the price of Low Frequency Detector?

Low Frequency Detector is a paid application, priced at $9.99.

### Does Low Frequency Detector have ads?

No, Low Frequency Detector does not contain advertisements. It is a paid application without any ad-supported elements.

## Version history (last 5 releases)

### 8.1 — 2026-08-06

- Improved internal processing and performance.

### 8.0 — 2026-02-16

- Improved internal processing and performance.
- Requires iOS 26.2 or later.

### 7.0.1 — 2025-12-20

- Improved internal processing and performance.
- Requires iOS 18.7 or later.

### 7.0 — 2024-12-31

- Renewed UI design.
- Requires iOS 18.2 or later.

### 6.0 — 2023-09-28

- Improved internal processing and performance.
- Requires iOS16.6 or later.

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## More apps by TOON,LLC

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All apps by TOON,LLC: https://appshunter.io/developer/633948723

## Related topics

[low frequency detector](https://appshunter.io/ios/topics/low-frequency-detector) · [low frequency](https://appshunter.io/ios/topics/low-frequency)

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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 2026-09-04.*