SPLnFFT is a sound level meter (noise meter) for your iPhone or iPad with many advanced features: frequency analyzer, frequency meter, test signal generator, dosimeter, ...

This soundmeter App is the only one for iOS recommended by the "Laborers' Health and Safety Fund of North America".
Here are extracts from other reviews:
"our favorite sound measurement app"
"SPLnFFT is comprehensive, easy to use"
You will find more reviews here:

For daily use, a very simple interface displays the level of exposure: if orange or red, protect your ears !
Professional users will take advantage of a wide range of accurate and reliable measurements: Leq, peak, L10, L95, taktmaximal, frequency analysis, histogram, dosemetering, ... A&C weightings are compliant with ANSI® S1.42 standard. "468" refers to ITU-R 468-4

>>> Some KEY INFORMATION <<< :
- you absolutely need to allow access to microphone to use this App
- screen rotation must be un-locked
- there are built-in help messages (speech bubble). Need more ? Contact us !: email, blog, Facebook,...
- do not expect to measure as low as 0dB(A) in a quiet room, for these 2 reasons: 30-130dB(A) is the standard usable range for sound level meters and anyway a standard quiet room is around 30dB(A) whereas a typical anechoic chamber is 10 to 20dB(A)
- to change frequency weightings (dB(A),dB(C),...) a LONG PRESS is required (1/3rd of a second). This is to avoid accidental changes

Top digital display is for measurement of sound power in 'slow' mode (averaged on 1s). Central analog display is for 'fast' mode (averaged on 1/8th s). But it can display 'slow' mode as well on request: just click on 'fast' label.
Peak and average values are displayed below and are holded until you touch the 'reset' label. The videos on Youtube reveal more details.

Bottom view is a real time FFT (frequency analysis). You will notice that predominant frequency and next one are highlighted. Their frequencies and relative power are displayed on the right. If your input signal is a pure tone then this App will lock on its frequency and display a very accurate result.
Green line is the result of a real time FFT done with 1024 points. Purple line is the averaged FFT (exponential filtering done on power of each frequency). Blue line is a copy of what the purple line was when the user froze the display the last time.
A test tone at 1kHz or a white noise or a pink noise can be generated and sent to right and/or left outputs (select the type you want in BEEP tab). This FFT view - more precisely an upsized version of it - can be exported as a picture in your own photo library, using the camera button (when display is frozen only). This picture can be exported in a mail as well.
The display can be flipped upside-down to ease reading: just rotate your iPhone while holding it vertically.

As for ALL sound meters (thus including this one and all others at any price), calibration is suggested if you want to reach extreme precision. This is enabled in this App thanks to a slider to apply some compensation and to three non volatile memories (choice to be made in MIC. tab). How to ? For calibration, you need and external reference, either a calibrated sound meter, or a calibrated noise source.
Note as well that the tiny embedded loudspeaker cannot reproduce extreme frequencies. Thus if you want to hear a real white or pink noise, you will need to use a quality headphone or HiFi system.

This App was designed seriously for our own needs, by a signal processing expert, and is regularly updated to maintain accuracy and reliability.

***** Any comment, any feedback ? Click on 'support' in iTunes: there is a blog for this. You can even contact us directly by email or through the dedicated FaceBook page (note 'send email' top right) *****

What’s New

Version 6.91

Minor update for the HTTP GET feature: unique identifier added

Ratings and Reviews

4.6 out of 5
22 Ratings
22 Ratings
Eivind T ,

My best app purchase

I use it all the time to understand more about the audio environment around me.

I bought it several years ago. The author has all the time kept the app updated and current. Seems to be someone who cares deeply and really knows the domain.

Gigabit1 ,

Indispensable app

This is a must-have for anyone who cares about sound, audiophiles, sound engineers and even concert goers. Use this to adjust tone controls on your car stereo or see how loud that club really is. With this app, I know for sure when to insert my earplugs.

I am not associated with the developers.

Seattle Rex ,

Loud Maintenance Noise Started

I fired up app to measure it while holding to toward the source, bring it down, look at the screen, there is a Nag asking me to leave a comment in here.

Even though I have rating nags disabled in iOS. Nice guys, real nice. Thanks for putting your needs above your customer’s needs.

Thanks for knowing your market. Cause that’s what people want to do monitoring noise. They really want to write ad copy in the App Store instead. I mean, why else would they launch the app, right?

“But but it help us when people rate!”

Sure and it helps me when people send me money. Can I spam your phone requesting donations from time to time? I mean, what’s the big deal? I won’t do it that often?

Anyway, here’s the comment you wanted. You’re welcome.

Developer Response ,

Thanks for the feedback.
The App will ask for a feedback once every ten days. Provided you launch it that particular days. It will never ask you more that once in a particular day, except if you are used to kill the App instead of letting it go background.
If you feel this is still too much, just go to "Conf" and select "Disable verbose mode".


Fabien Lefebvre
7.7 MB
Requires iOS 9.0 or later. Compatible with iPhone, iPad, and iPod touch.
English, French, German
Age Rating
Rated 4+
© 2010 Fabien LEFEBVRE
In-App Purchases
  1. Export raw data to Dropbox + PRO features $4.99


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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