SPL7.10 - App Store

SPL is a professional-grade digital sound level meter (decibel meter) for your iPad, iPhone or iPod touch. It includes all of the modes, filters, and features that you would expect from a professional ANSI or IEC Sound Level Meter. All filters and averaging modes meet or exceed the criteria for ANSI Type 1 standards or better. SPL is created from the same team who brought you the Audio Toolbox and ATB Plus.

Store Results -- Uses the same powerful Save / Recall engine as our premier app, AudioTools. Allows storing GPS and time-stamped results, and exporting them to your computer.

You can also use SPL with our calibrated iPhone measurement mic, iTestMic, or iAudioInterface.

The screen flips if you turn the phone upside down, so that you can point the built-in iPhone mic directly at the sound source.

*** Modes: Slow, Fast, Impulse, Peak, and Leq.

*** Filters: A and C weighting, and 10 octave band filters.

*** Includes a resettable Max field to track the highest reading.

*** Includes a reference field (except in Leq mode) so that you can set a reference level and do seat-to-seat comparisons.

The SPL meter can be fully calibrated. It comes preset with the calibration for a typical iPad, iPhone, and iPod Touch. Most iOS devices will be within a few dB of this reading. If you have access, even temporarily, to a calibrated sound level meter, just use the calibration field on the settings scree to match the meter, and you will be accurately calibrated.

Also, see our other professional-grade audio apps: AudioTools, our premier suite of professional-caliber audio and acoustics test apps, Speaker Pop, to test speaker polarity, and RTA, a real-time analyzer for the iPhone.

And, we have a group of calibrated, accurate measurement microphones, including iTestMic,iTestMic2, and iAudioInterface2, that allows full professional results for Type 1 or Type 2 measurements.

This will allow measuring a range from approximately 30 dB SPL to 130 dB SPL. Each mic will include a calibration factor that you will enter into the SPL app for calibrated measurements. This mic will also work with Speaker Pop, our speaker polarity tester, FFT, RTA, ETC, and other acoustical measurement apps in our AudioTools app that is available now.

Also, see our iAudioInterface2 system, which supports any pro test and measurement mic.

Now includes an iPhone internal mic compensation filter, to cancel out the low-frequency roll-off present in the iPhone and other iOS devices.

See our other audio apps, including AudioTools.

Version History -Bug fixes and stability improvements
-Support for latest iOS versions 7.10 Sep 11 -Bug fixes and stability improvements 7.9 12/22/2025 -Fixed SPL not running after storing data 7.8 12/01/2025 -Updated for new iOS devices
-Bug fixes and stability improvements 7.7 11/24/2025 -Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements 7.6 11/24/2024 -Added taking a photo as a screen background to document what is being tested
-Added screen recording to save a video of the sound levels with the photo as the background if desired
-Added more device support 7.5 10/18/2024 -Bug fixes and stability improvements 7.4 08/05/2024 -Updated for latest iOS devices and calibrations
-Bug fixes and operational improvements 7.3 07/10/2024 -Updated for latest iOS devices and new iOS versions
-Bug fixes and stability improvements 7.2 10/19/2023 -Bug fixes and improvements
-Support for more iOS devices and iOS versions 7.1 07/13/2022 -Bug fixes and stability improvements
-Updated for latest iOS and devices 7.0 09/25/2021 -Bug fixes and stability improvements 6.1 02/04/2021 -Bug fixes and stability improvements
-Support for direct data file access in Files app
-Support for latest devices and iOS versions 6.0 08/20/2020 -Bug fixes and stability improvements 5.7 11/05/2019 -Fixed issues on iOS 13
-Bug fixes and stability improvements 5.6 10/09/2019 -Updated for any iOS 9 or later
-Fixed issue with setup menu
-Bug fixes and stability improvements 5.5 08/13/2019 -Updated for latest iOS and new devices
-Bug fixes and stability improvements 5.4 08/07/2018 General
- Added Calibration Error Report link to support page
- Fixed crashes on iOS 8 and iOS 9
- Fixed issue with multiple Studio Six Digital apps trying to access our accessories
- Updated App Store in-app purchase accessing and authorization for iOS 11


Live Calibration Updates
- Added cloud-based database for all iOS devices that can be updated in real time
- All devices included
- Includes local default files, in case a device has no internet connectivity
- Different databases for each major iOS version, starting with iOS 10
- New iPhones added to live calibration database 5.3 09/26/2017 -Bug fixes and stability improvements 5.2 08/28/2017 * Updated for latest iOS devices.
* Removed support for older iOS versions, now requires iOS 8 minimum.
* Added simultaneous background launch protection to prevent problems in iOS 10 when plugging in iTestMic or iPrecisionMic when more than one Studio Six Digital app is installed. 5.1 03/18/2017 -Updated for iOS 10 and iPhone 7
-Fixed measurements starting after going to setup page 5.0 11/21/2016 - Updated to support iPhone 7 and iPhone 7 Plus. 4.9 09/24/2016 ** SPL Pro, sound level meter app that meets industry Class 1 standards

** Bug fixes and calibration updates 4.8 05/09/2016 SPL Pro -- Class One calculations meet all ANSI and ISO standards for Type 1 Sound Level Meters.

Now supports multi-tasking Slide Over and Split Screen on newer iPads that support this feature.
Calibrations adjusted for all iOS devices. 4.7 04/28/2016 ** Best professional iOS-based Sound Level Meter.

** Updated for iOS 9.3. New calibrations loaded for all iPads.

** Save/Recall Updates
* New! Auto-save file name options are now available from the Save/Recall screen mini-menu. Tap the icon with 3 lines.
* New! Added auto-save Name List to store frequently-used file names.
* Fixed auto-save sequence numbers resetting after app relaunches.
* Fixed case where files may not be saved when using auto-save immediately after Delete All Files.
* Fixed possible crash if action buttons were tapped with no file name selected.
* Improved auto-save naming.

**Improved referral screen layout.

**Now always uses 24-bit audio mode if iPrecisionMic is present.

**Fixed an issue where internal mic gain could change coming out of the background

** Support Menu
* Fixed Forum page access.
* Fixed "Rate This App" access.
* Fixed access to other Studio Six Digital webpages 4.6 04/12/2016