Opening the iTunes Store.If iTunes doesn't open, click the iTunes application icon in your Dock or on your Windows desktop.Progress Indicator
Opening the iBooks Store.If iBooks doesn't open, click the iBooks app in your Dock.Progress Indicator

iTunes is the world's easiest way to organize and add to your digital media collection.

We are unable to find iTunes on your computer. To buy and download logSPL by Fabien Lefebvre, get iTunes now.

Already have iTunes? Click I Have iTunes to open it now.

I Have iTunes Free Download
iTunes for Mac + PC


By Fabien Lefebvre

Open iTunes to buy and download apps.


This App is a full featured sound level meter, designed by a signal processing expert. It is iPhone/iPod/iPad compatible and adapts itself to the actual screen resolutions ("HD", "retina").

It consists in two parts: half top for basic features, half bottom for advanced ones (L95, %D, ...).

Half top was thus designed to be extremely easy to use. Only two settings are requested:
* select 'fast' or 'slow' update rate, which corresponds to 2 different integration periods
* select the type of weighting: A or C or Z (Z meaning roughly: no filtering)
These settings are saved when exiting the App.

Some tips for weighting:
* select A to evaluate the feeling of a person against a noise
* select Z to balance an audio system

Supports upside-down orientation.

The min and max values are monitored and displayed in green in the upper view. An average value (Leq, LAeq, ...) is computed on top of this: the green triangle. Take care that this latter corresponds to the logarithm of the average power and not to the average of logarithm values, which is completely different. Integration time for this average value is: all time since start-up of the App or last reset.
To reset these extreme and average values, touch the text named RESET.

Bottom view is used to display an historical curve. A grid is visible, with lines every 10dB vertical and 10s horizontal.

Half bottom now:
* a real-time histogram is displayed on left side
* it can compute L%: L95, L50, ...
* it can make some dosemetering: for this you need to set threshold, criterion and exchange values. This is for advanced users due to the complexity of underlying concepts

As for all sound-meter (at any price, hardware or software), you should calibrate it against a reference in order to achieve best accuracy. For this go to Mic. tab to add or remove a fixed offset to the measured values.

Any question ? Click on the Facebook icon !

What's New in Version 4.0

Major update that improves by the way accuracy in higher range of measurement. A new procedure appears, to align internal gains: the 'SET' procedure. Just go to Mic. tab, select 'SET' when available (depending on device type), and follow instructions. It will generate a beep that will last few seconds thus find a quiet room first. Fortunately this procedure is to be run only once.
From now logSPL can be seen as a derivative of SPLnFFT. Both Apps will share the same core, with this difference: SPLnFFT is a full featured sound level meter targeting advanced users whereas logSPL is designed to be simple to use, for standard usage, yet with the same accuracy.
Note: click on the text to change displayed data and information


iPhone Screenshot 1
iPhone Screenshot 2
iPhone Screenshot 3
iPhone Screenshot 4
iPad Screenshot 1
iPad Screenshot 2
iPad Screenshot 3
iPad Screenshot 4
View In iTunes
This app is designed for both iPhone and iPad
  • $2.99
  • Category: Utilities
  • Updated:
  • Version: 4.0
  • Size: 0.6 MB
  • Languages: English, French
  • Seller:

Compatibility: Requires iOS 7.0 or later. Compatible with iPhone, iPad, and iPod touch.

Customer Ratings

0 0 0 We have not received enough ratings to display an average for the current version of this application.
All Versions: