Low Frequency Detector Support Page

Description - iOS app / Low Frequency Detector

Low Frequency Detector

"Low Frequency Detector" is a new acoustic measurement tool for detecting low frequency sound/noise that is hard to hear in the normal situation. It supports very lower frequency range less than 100Hz by our proprietary sound sensing technology. This app can also display the frequency component of the low frequency sound by examining by 1/3 octave band analysis and FFT analysis.

The human ear is insensitive enough to become a low frequency. If you may be exposed to the noise of neighboring constructions and factories without noticing, you may have a feeling bad and a sense of oppression. In this case, you can check what type of low frequency noise exists by simple operation of this app.

Please to click the following link to download "Low Frequency Detector" from App Store^TM. It will be open the download page on App Store^TM.

Installation of iTunes is required.

Communications charges when connecting to the App Store will be borne by the customer.

* iPhone is a trademark of Apple Inc., registered in the U.S. and other countries.

* App Store is a service mark of Apple Inc.

Products Information

Version : 1.4

Release date : May 17, 2018. UTC

Size : 0.7 MB

Category : Utilities, Life Style

Recommendation : Compatible with iPhone. Requires iOS 11.3 or later. iPod and iPad products are not recommended.

Features

Optimized for iPhone, Compact code size.

Low frequency power level measurement from 5Hz to 100Hz (LF Level): Flat characteristic, Updating indication of measurement period 1sec.

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 transition graph chart (Time) for displaying the relative sound level of low frequency sound

Timer measurement (Sec): 10 - 60 seconds / 10 seconds unit.

Instantaneous maximum value display (Max)

Snapshot (Snap) on the measurement display screen.

Low Frequency Sound

In general, the low frequency sound is a sound wave with 1 Hz to 100 Hz. By depending on its frequency component and sound level, it is different the degree of influence on the human body and the noise sensation. This app can also display the frequency component of the low frequency sound by examining by 1/3 octave band analysis and FFT analysis.

Operation procedure

Measurement analysis of low frequency sound is performed in the following step. Be sure to set the measurement conditions in Step 1) and Step 2) once before starting the measurement analysis.

1) Tuning(Reference signal adjustment)

Adjust the hardware volume of the iPhone and adjust the playback sound of the reference tone 1 kHz to fit the power level bar between 40 to 60.

2) Calibration

Signal calibration is performed in as quiet a sound environment as possible. It takes 15 seconds and stops automatically. The measured value at this time is applied as the reference noise level, so this app measures the relative noise value for the low frequency range. The previous calibration information can be maintained in ver 1.1.

3) Measure

In low frequency sound measurement, it analyzes the ambient sound from the built-in microphone while playing the reference signal (1kHz). Perform measurements in places where low frequency noise is expected to occur. This measurement is automatically stopped within the time specified in the timer setting.

4) Measurement display

The measurement indication can select either 1/3 octave band frequency analysis, FFT analysis, or low frequency sound level time transition chart. These measurement analysis displays are updated in real time. In addition, after the completion of the measurement, you can call the maximum instantaneous value in the Max button.

Sound Level

The sound level shows the power level (Leq) of the audible band and the low frequency power level (LF Level) less than 100 Hz. At this time, these update period are "Leq" with 0.2 seconds and "LF Level" with 1 second.

1/3 Octave Band Analysis

In this analysis, the power spectrum in the low frequency sound is displayed by the frequency component band that is divided into fourteen from the center frequency 5Hz to 100Hz. This display is updated in real time, and you can intuitively grasp the frequency component of low frequency sound. In addition, the white line display shows the frequency characteristic with the frequency weight corrected for the G characteristic.

FFT

In this analysis, FFT analysis (Fast Fourier Transform) is performed on the low frequency sound, and the power for each frequency component is displayed in spectrum so that the instantaneous frequency peak can be observed. This display is updated in real time, and you can intuitively grasp the frequency component of low frequency sound. In addition, the white line display shows the frequency characteristic with the frequency weight corrected for the G characteristic.

Time transition graph chart

In this analysis, the time transition of the observed low frequency sound power level (LF Level) is displayed as a graph chart. The vertical axis shows the power level and the horizontal axis updates and displays in real time.

Maximum display

When you tap the Max button after the measurement is completed, the instantaneous maximum value (LF Level) is displayed. In each analysis mode, you can display the analysis result of the timing with the maximum value.

Snap Shot

By tapping the Snap button, you can save the current measurement display to "Photos".

Product Information

By tapping "Information" button, it is displayed the product information. If you tap the "Support Information", Safari starts and you can see our support page. If you tap the "Other Apps Information", you will see our App's information on the "App Store".

Release Information

Version 1.4 was released on May 18, 2018. UTC

Version 1.3 was released on April 17, 2018. UTC

Version 1.2 was released on February 25, 2018. UTC

Version 1.1 was released on May 9, 2017. UTC

Version 1.0 was released on January 26, 2017. UTC

Note

Sound measurement of the low frequency range is a level difference with respect to the reference signal 1kHz, which indicates the relative power value. The frequency characteristic of the low frequency measurement is the flat characteristic.

The 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 low frequency range, it is not recommended to measure a huge volume sound near a 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.

There are variations in analysis results due to individual differences of iPhone devices.

The authorization for access to the built-in microphone and Photos will be confirmed by the iOS system at first access. Please enable access to Microphone and Photos.

Request for review

Please send a review of your comments and requests for this app. We will use your review to improve our products. Thank you for your cooperation.

Please fill in your review by accessing from iOS device.

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Support index

• Description
• Products Information
• Features
• Low Frequency Sound
• Operating procedure
• Sound Level
• 1/3 Octave Band Analysis
• FFT Analysis
• Time transition graph chart
• Maximum display
• Snap Shot
• Product Information
• Release Information
• Note
• Request for review
• Contact us