Sound Level Analyzer


"Sound Level Analyzer" is a standard sound level measurement iPhone app with sound frequency analysis tools.

Available in variety of applications as the neighboring environmental noise measurement, audio system check, vehicle interior noise check, sound check of live events, and more.

"Sound Level Analyzer" has additional analysis modes, which are time graph, frequency realtime analyzer (RTA) and FFT analyzer.

It can be used to analyze the characteristics for the sound/noise source.

The latest version supports iOS 17 and improves stability and performance. Changed the display position of the occurrence time and the maximum level in "Display Max" at P.S. mode.

sla_main sla_ps

The WHO has proven direct links between noise and health risks; tinnitus, sleep disturbance, stress, cognitive impairment, heart diseases and annoyance in general. Please check your environmental noise for your wellness.

"Sound Level Analyzer" has received the highest rating as a sound level meter app in the research paper of acoustic academic journal "Applied Acoustics". (Paper: ”Testing the accuracy of smartphones and sound level meter applications for measuring environmental noise”, Enda Murphy, Eoin A. King ; Applied Acoustics 106(2016)16-22.)

In addition, the high-end app "Sound Level Analyzer PRO" has more powerful sound / noise analysis function in addition to the sound level measurement function, so please consider using these apps for your advanced requirements.

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

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Products Information

Version : 7.0
Release date : September 30, 2023. UTC
Size : 0.7 MB
Compatibility : Compatible with iPhone. Requires iOS 16.6 or later.
Category : Utilities, Life style


"Sound Level Analyzer" has the following features:

Sound level measurement (dB) : Main (Leq)

- Leq (equivalent sound level), Min (minimum value), Max (maximum value), Avg (time average equivalent sound 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

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

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

- 1/3-octave band center frequency(Hz): 25, 31.5, 40, 50, 63, 80, 100, 125, 160, 200,
250, 315, 400, 500, 630, 800, 1k, 1.25k, 1.6k, 2k, 2.5k, 3.15k, 4k, 5k, 6.3k, 8k, 10k, 12.5k, 16k, 20k

- FFT frequency range settings : 100Hz - 20kHz (FFT All) / 100Hz - 3kHz / 3k - 6kHz

- Measured value display function in 1/3 oct band response analysis. (OctVal)

- Power spectrum display function at the time of occurrence of Lmax. (Display Max)

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


"Sound Level Analyzer" 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

Important initial settings (iOS permissions)

In order for this app to work properly, it is necessary to make the following initial settings related to the iOS system.

Microphone access permission setting

At the initial startup after installing the app, the iOS system asks for permission to access the built-in microphone. In this case, you need to enable access to "Microphone".

If you have not enabled this setting, this app can not work by privacy restrictions of the iOS system. Please enable the access permission on the iOS setting, "Settings > Privacy > Microphone".

Photos access permission setting

When the first time you save an image data with Snapshot, the iOS system asks for permission to access the "Photos" library. In this case, you need to enable access to "Photos".

If you have not enabled this setting, this app can not work by privacy restrictions of the iOS system. Please enable the access permission on the iOS setting, "Settings > Privacy > Photos".

Operation Mode

"Sound Level Analyzer" has two 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 (Leq) : Sound level measurement (dB)
P.S : Power Spectrum

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

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 (Leq) mode at the first boot-up.

MAIN (Leq) : Sound Level Measurement

"MAIN (Leq) 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.

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

sla_main_2 sla_main sla_main

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

Leq: Equivalent sound level - Instantaneous value of sound level (noise level) (dB)
Avg: Time average equivalent sound level - Time moving average value (dB)
Min: Minimum sound level - Minimum value within the measurement time (dB)
Max: Maximum sound level - Maximum value within the measurement time (dB)

It also displays a short-term time variability graph at the same time. This graph shows the sound level fluctuations for the past 20 seconds. The graph shows the Leq level (white bar), the Avg level (green line), and the moving average level for 10 seconds (orange line).

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 - 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 calibration value window in Info view, the input keyboard will appear. If you have the 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.

[FFT frequency range]

All : 100Hz - 20kHz
Scope 1 : 100Hz - 3kHz
Scope 2 : 3kHz - 6kHz

sla_all=2 sla_scope1 

By tapping "OctVal" button, it can display the measured values for each band of 1/3 octave band analysis in real-time.


In addition, by tapping "Display Max" button, it can display the frequency spectrum characteristics at the moment when the maximum sound level "Max" has occurred.


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

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

Timer time:1 min / 5 min / 10 min / 15 min / 20 min / 30 min / 1 hour


Product Information

Tap "Setting" button, it is displayed the product information and function description.

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


Release Information

"Sound Level Analyzer" ver 7.0 was released on September 30, 2023. UTC
"Sound Level Analyzer" ver 6.0 was released on October 5, 2022. UTC
"Sound Level Analyzer" ver 5.0.1 was released on November 6, 2021. UTC
"Sound Level Analyzer" ver 5.0 was released on November 3, 2021. UTC
"Sound Level Analyzer" ver 4.2 was released on February 17, 2021. UTC
"Sound Level Analyzer" ver 4.1 was released on November 4, 2020. UTC
"Sound Level Analyzer" ver 4.0 was released on May 18, 2020. UTC
"Sound Level Analyzer" ver 3.1 was released on April 2, 2019. UTC
"Sound Level Analyzer" ver 3.0 was released on November 13, 2018. UTC
"Sound Level Analyzer" ver 2.3 was released on May 16, 2017. UTC
"Sound Level Analyzer" ver 2.2 was released on March 24, 2017. UTC
"Sound Level Analyzer" ver 2.1 was released on March 4, 2016. UTC
"Sound Level Analyzer" ver 2.0 was released on December 12, 2015. UTC
"Sound Level Analyzer" ver 1.3 was released on May 28, 2015. UTC
"Sound Level Analyzer" ver 1.2 was released on March 24, 2015. UTC
"Sound Level Analyzer" ver 1.1 was released on September 3, 2014. UTC
"Sound Level Analyzer" ver 1.0 was released on June 10, 2014. UTC


The standard noise measurement range is 30-130 dBA, and even in a quiet room of the household, the measured value is approximately 30 dBA. In any silent environment, it will not be measured with very low noise levels, such as 0 dBA.
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.

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