SPL Graph is an audio Sound Pressure Level (SPL) chart recorder for the iPhone, iPad, and iPod Touch. It works by averaging the SPL for one second, applying an optional weighting filter, and plotting the sound level.
The app works very well with the built-in iOS device microphone. To upgrade the app to true pro standards, add our iTestMic or iAudioInterface2 with a microphone, and get ANSI or ISO Type 1 o2 2 results.
SPL Graph can record up to 24 hours of sound level data, with single second resolution. The graph starts with a one-minute window, and as a minute is recorded, the graph re-scales automatically and adds another minute to show the data collected so far. The overall SPL leve, or LEQ, is displayed for whatever portion of the test is showing on the graph.
Tap the green play button to play back the recorded audio, and use the cursor to scrub the audio location on the graph. Use this feature to listen to events that you can see on the graph.
With the optional octave logging module, you can also record the octave or 1/3 octave band levels. And, you can view the data on the 3D plot for a graphical view of frequency over time.
You can scroll and scale the graph vertically, in dB, by using standard swipe and pinch gestures. You can also scroll and expand and contract the time axis using gestures. Zoom out to a full 24 hours, or zoom in to a single minute, showing second resolution. Double-tap the screen to zoom out to show the entire graph on the screen.
The time scale grid changes dynamically, highlighting minutes, ten-minute, and hour lines as as it runs.
As the graph runs, the overall LEQ (average SPL) for the entire time period is computed and displayed on the screen. Swiping across the graph brings up a cursor that displays the exact dB level and time for any point on the graph.
You can turn on audio recording, so that you have a record of the sounds that were happening while the graph was being stored. You can use this to figure out exactly what the sound was that caused a peak on the graph, for example.
If you exit the app, or are interrupted with a phone call, the graph data will not be lost. SPL Graph will automatically save the graph, and reload it when you next open the program. You can also save a graph in one of ten files on the iPhone, so that you can recall the graph later.
SPL Graph supports saving graphs directly on your iOS device. You can recall these graphs and bring them up on the screen, and listen to the sounds that were made while the graph was recorded. You can also store an image of the screen to your photo roll.
You can also export data in tab-delimited files for XLS import. Dropbox is supported for automatic file transfer.
The filters are all ANSI type 1 or better, and include A-weighting, C-weighting, and all octaves band filters from 32 to 16kHz.
Like all Studio Six Digital audio apps, SPL Graph supports calibration. The app ships calibrated for the iOS device that it is running on. If you have access to a calibrated SPL meter you can calibrate your iPhone.
NOTE: This app was renamed from "LEQ Graph".
You can use SPL Graph on an iPod Touch second generation by using a headset microphone. If you have first generation Touch, you can use the app only with a third-party microphone input adapter. See our web site for more detail.
Also, see our other great audio and acoustical analysis apps: AudioTools, SPL, SPL Meter, RTA, ETC, RT60, FFT, Generator, and Speaker Pop.
Great app but it crashes with iOS 4.3.3 when trying to adjust db calibration. An iPad version would be nice to have!
I really appreciate the graph and the ability to save the graph image. The app saves a screen capture of the graph image to your iPhone camera roll so you can document your readings. Worth the price!
I've found many uses for this application, the most valuable being the ability to measure sound exposure in various environments. I hope the developer will consider adding the ability to graph peak spl exposure concurrent to average spl. This is the only reason why I did not add a fifth star. Otherwise the interface is stable, effective, and easy to use.
Great tool for finding "dead spots" while balancing systems! Giving me indicators where to aim speakers for even coverage. A+++ app. Can't wait for the interface!
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