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Sound Level Analyzer PRO


"Sound level analyzer PRO" is a professional-grade sound level measurement app further evolved from our standard app, “Sound Level Analyzer".

"Sound Level Analyzer PRO" is a new integrated sound measurement app with sound level measurement and powerful sound analysis tools. It can display automatically the instantaneous sound level such as environmental noise, specific sound sources, live sounds in real-time. In addition, this app has advanced sound analysis functions that can perform "Power Spectrum Analyzer", "Time Course graph", and "Statistical Analysis (Histogram, Percentile Level)". It can be used to analyze characteristics and trends of occurrence for the noise/sound source.

slapro_main slapro_ps_max slapro_tc

slapro_sa_hist slapro_sa_ln

Please to click the following link to download "Sound Level Analyzer PRO" from App StoreTM. It will be open the download page on App StoreTM.

It will move to another site, download from Apple Store

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

# Product name : Sound Level Analyzer PRO

Version : 1.0
Release date : December 12, 2017. UTC
Size : 1.0 MB
Recommendation : Requires iOS 11.2 or later.
Category : Utilities, Life style


"Sound Level Analyzer PRO" has the following features:

Sound level measurement (dB) : Main

- Leq (equivalent noise level), Lmin (minimum value), Lmax (maximum value), Lavg (time average equivalent noise level)

- Frequency weighting correction characteristics : A (for noise level meter), C (for sound level measurement), Z (no correction)

- Time weighting characteristics : Fast = 0.125 sec, Slow = 1.0 sec

- Display Range : 0 - 130dB

- Measurement Time:Maximum 8 hour linked on a timer.

Power Spectrum (P.S.) : View of frequency spectrum analysis

- Spectrum analyzer function : FFT analysis, 1/3-octave band response analysis.

- Display frequency band: 100Hz - 20kHz or 100Hz - 8kHz or 8k - 16kHz

Time Course (T.C.) : View of time-history of the sound level.(graphical representation after measuring completion.)

- Time-domain fluctuation level display function: up to 8 hours linked on a timer.)

Statistical Analysis (S.A.) : Statistical analysis of sound level at A-weighting and Fast. (analysis display after measuring completion.)

- Histogram : Displays all detected sound level distribution as a percentage.

- Percentile level (LN:dB): Display the levels of L05 / L10 / L50 / L90 / L95 on the percentile level graph.

Calibration function : level correction value setting, -20 to +20dB / 0.1dB unit
Measurement timer function : 1 minute / 5 minutes / 10 minutes / 15 minutes / 20 minutes / 30 minutes / 1 - 8 hours (1 hour unit)
Snapshot : Save measurement display with time stamp to Photos.


"Sound Level Analyzer PRO" can be used in applications such as the following:

Live Sound
Environmental noise measurement
Setting and Tuning of Audio system
Installation of Audio equipments
Installation of Car audio equipments
Architectural acoustics
Device management

In addition, the followings are examples of the magnitude of the sound level in the measurement of environmental noise.

130dB : Engine sound of Airplane
110dB : Horn of Car
100dB : Noise of passing train
90dB : In loud factory
80dB : In the train, Vacuum cleaner
70dB : Noisy office, Noisy street
60dB : Quiet Car, Normal conversation
50dB : Quiet office
40dB : In the library, Quiet residential area
30dB : Outskirts of midnight, Whisper
20dB : Sounds of rubbing leaves

Operation Mode

"Sound Level Analyzer PRO" has four types of measurement analysis modes. By tapping on each mode button, you can select one of the modes and display it. The function of each mode is as follows.


[Measurement analysis mode]

MAIN:Sound level measurement (dB)
P.S.:Power Spectrum
T.C.:Time Course (graphical representation after measuring completion.)
S.A.:Statistical Analysis (analysis display after measuring completion.)

"MAIN mode" and "P.S. mode" are also switched during measurement operation.

"TC mode" and "S.A. mode" can be selected and displayed only after the sound level measurement is completed.

The access permission to the microphone will be confirmed from the iOS system at the first start-up. Please enable access to the microphone.

In addition, it will start up in MAIN mode at the first boot-up.

MAIN : Sound Level Measurement

"MAIN mode" makes the sound level measurement in general. In this case, by applying the appropriate Frequency Correction, Time Correction, and Level Correction, you can be the best sound level measurement.

By tapping play button to start the sound level measurement, and it then pause by tapping it again.


Sound level measurements are displayed measured values​of Equivalent continuous sound level (Leq), minimum value (Lmin), maximum value (Lmax) and Time average equivalent noise level (Lavg) in dB units. The Leq is also displayed as a bar graph.

It can be measured as parameters, Time weighting correction, Frequency weighting correction, and Level calibration, to set as follows:

[Time weighting correction]

It specifies the time constant of calculating the sound level. Please set in accordance with the occurrence tendency and type of sound source.

FAST : 0.125 sec (Default)
SLOW : 1.0 sec

[Frequency weighting correction]

It is a weighting filter that limits the frequency band of the input signal. Please set according to the measurement applications.

A : A correction - The noise measurement by general audibility correction (Default)
C : C correction - Sound pressure level measurement for wideband sounds and music
Z : Non correction

[Level Calibration]

You can specify the reference level in the offset range. Tap the "Setting" button, the calibration input window will appear. If you have a standard sound level meter, please use it to adjust the reference level.

Offset ranges : -20dB to +20dB in 0.1dB unit

P.S. : Power Spectrum

"P.S. mode" displays frequency spectrum analysis in real time. Measurement is displayed by 1/3 octave band response and FFT analysis.

The 1/3 octave band analysis displays the signal response of the input signal's frequency spectrum in 1/3 octave and 24 band (100 Hz to 20 kHz). FFT analysis displays the FFT spectrum by Fast Fourier transform.

You can also switch the frequency range and display it.

- All: 100 - 20 kHz

- Scope 1: 100 - 8 kHz

- Scope 2: 8000 - 16 kHz

slapro_ps_all slapro_ps_sc1 slapro_ps_sc2

In addition, you can display the frequency spectrum characteristics at the time of maximum equivalent noise level (Lmax) is occured by tapping "@Max" button.


T.C. : Time Course

"T.C. mode" displays the time course graph of the sound level.

In conjunction with the timer, fluctuation data of the sound level up to 8 hours is recorded, and the time course graph can be displayed in all the measurement time. "T.C. mode" can be selected only after measuring completion.

The time course graph is displayed with time as Y axis and sound level (dB) as X axis, and it can be displayed by scrolling. The moving average level can also be displayed.

In addition, you can select graph display in 1 hour unit with the buttons from "0" to "7" at the bottom.


S.A.:Statistical Analysis

"S.A. mode" displays the statistical analysis focusing on sound level fluctuation.

In conjunction with the timer, fluctuation data of the sound level up to 8 hours is recorded, Histogram and Percentile level can be displayed as a sound level statistical analysis on all measurement time. "S.A. mode" can be selected only after measuring completion.


It displays the noise level distribution showing the occurrence frequency of sound level as a percentage. It can intuitively grasp which sound level occurred frequently in all measurement time. It may be shown the occurrence of steady noise and the distribution trend of the noise floor. The X axis is the sound level (dB), and the Y axis is the incidence of each sound level. In addition, the cumulative relative frequency distribution curve is also displayed.


Percentile level

It displays the percentile level LN (L5, L10, L50, L90, L95), and the cumulative relative frequency distribution curve.

In this statistical analysis, when the total time exceeding a certain level corresponds to N% of the measured time in the fluctuating noise within the measured time, the noise level is expressed as N% hourly noise level (LN). The percentile level can be used to evaluate the noise environment where the noise level is random or it fluctuates dramatically.


Also, in the sound statistical analysis, the following measurement time is required. Please note that the required measurement time varies depending on the timer setting.

[Timer setting : Measurement Time]

- 1 min : 10 sec or more

- 5 min : 30 sec or more

- 10 min over : 60 sec or more

Snap Shot

If you tap "Snap" button, you can capture the measured image to Photos. It is possible in all modes.

At the first time, the confirmation of access to Photos is required once from iOS system when you press "Snap" button.


If you tap "Setting" button, Measurement Timer settings is displayed

Timer time can be selected from a minimum of 1 minute to a maximum of 8 hours.

By tapping "Close" button, it will return to the previous measurement view.

Timer time:1 min / 5 min / 10 min / 15 min / 20 min / 30 min / 1 - 8 hour(1 hour unit)


Product Information

By tapping "Setting" button, it is displayed the product information and function description. If you tap "Support" button, Safari starts and you can see our support page.

By tapping "Close" button, it will return to the previous measurement view.

Release Information

Version 1.0 was released on December 12, 2017. UTC


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 can not access them by privacy restrictions of the iOS system. Please enable the access permission on the iOS setting, "Settings > Privacy > Photos or Microphone".

This app is adjusted the reference value for iPhone. However, the built-in microphone of your iPhone is likely to have a non-uniform gain. The more exact measurement should be calibrated using the absolute level calibration devices.

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.

It will move to another site, download from Aplle Store Please send a review message for "Sound Level Analyzer PRO".

Please fill in your review by accessing from iOS device.

Contact us

Inquire about this app please from below! Please contact us with the following details if you have any requests or problems.

1. Application name
2. Device model
3. iOS version
4. Country you live
5. Details about your requests or problems.

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