SPL Graph vs MIDI Aid
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
SPL Graph
This app analyzes sound pressure levels and environmental noise in real-time. It logs audio, captures video, and performs frequency analysis, with options for advanced octave band analysis and professional microphone integration. Receive email notifications for exceeding noise limits and auto-save data for continuous monitoring.
- Real-time sound pressure level analysis
- Audio recording and playback
- Optional video capture
- Octave and 1/3 octave band analysis
- 3D frequency plot
- Ln SPL value calculation
- Email notifications for noise limits
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SPL Graph is an audio Sound Pressure Level (SPL) environmental noise analyzer, real-time frequency analyzer, chart recorder and data logger. It includes: * Plot sound level over time * Record audio while plot is running, playback to identify sounds that may have caused problems * Capture video of events (optional in-app purchase) * Do octave and 1/3 octave band analysis (optional in-app purchase) * Show a 3D Plot of octave or 1/3 octave results * Calculate Ln SPL values, L01, L10, L50, L90, L95, LMax and LMin * Email notifications when sound exceeds pre-set limits * Auto-save results after set intervals, and email the results to you * Start another plot after auto-saving for continuous operation SPL Graph works by averaging the SPL for a period of time that can vary from 0.1 second to 60 minutes, applying an optional weighting filter, and plotting the sound level, recording the raw audio signal, if recording is turned on. For sound intervals of 1.0 second to 60 minutes, the optional octave and 1/3 octave logging modules allows storing the spectrum of the sound, for each interval. The app works very well with the built-in iOS device microphone. To upgrade the app to true professional standards, add our iTestMic, iPrecisionMic, or iAudioInterface2 with an appropriate microphone, and get ANSI or ISO Type 1 or 2 results. With iPrecisionMic, you can send the system in to our calibration lab and get a calibration certificate for ISO 61672 and ANSI S1.4. SPL Graph can record up to 24 hours of sound level data, with single second resolution. The graph starts with a one-minute plot 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 level, or LEQ, is displayed for whatever portion of the test is showing on the graph. Tap the play button to play back the recorded audio, and you can 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. Recordings can be compressed or uncompressed. 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. Use Dropbox or iTunes Files Sharing to export the results to your computer. You can also export data in tab-delimited files for XLS import using iCloud. The filters are all ANSI type 1 or better, and include A-weighting, C-weighting, and all octaves band filters from 32 to 16kHz.
MIDI Aid
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MIDI Aid is a MIDI monitor: connect your MIDI devices and see every incoming event in one clean, technical view. Whether you are debugging a synth patch, checking a controller mapping, or just curious what your gear is sending, MIDI Aid shows you what is really happening on the wire. CAPTURE • Live event log with precise timestamps • Start, pause, and resume capturing at any time • Clear the log with one tap • Follow mode keeps the newest events in view • Clear controls in the style of studio gear: a capture key, a status display with the live event count, and a Follow key with a light that shows when it is on UNDERSTAND • Every event decoded into plain language: notes with names and velocities, controllers with their standard names, program changes, aftertouch, pitch wheel, and more • Raw status and data bytes side by side with the decoded event • Hex or decimal display, your choice • Tap any event for a detail view including the full raw bytes FILTER • Focus on what matters: filter by device, event type, and MIDI channel • Channel events, system common events, and system real time events can be toggled individually • Mute noisy events like Timing Clock or Active Sensing with one tap • All 16 MIDI channels as pads: tap one to hide or show it • Each section shows how many of its filters are on DEVICES • Works with USB MIDI devices out of the box • Network MIDI sessions and Bluetooth MIDI devices set up at system level appear automatically SUBSCRIPTION • MIDI Aid Pro: try it free for one week, then 0.99 € per month (or the equivalent in your currency) • Cancel any time in your account settings • Bought MIDI Aid before it became a subscription? It stays unlocked for you: tap Restore purchase • Terms of Use: https://ramuslabs.com/midi-aid/terms/ MIDI Aid supports all 16 MIDI channels, running status, and System Exclusive messages. No account, no ads, no tracking. Your MIDI data never leaves your device. MIDI Aid only counts anonymously which features are used; a random install ID is added only if you allow it.
Screenshots
Verdict
The clearest difference is price: MIDI Aid at Free against SPL Graph's $9.99. MIDI Aid also leads on update cadence (every 6 weeks vs every 6 months). On ads, in-app purchases, device support and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
MIDI Aid is free to download; SPL Graph costs $9.99 up front. SPL Graph sells 5 in-app purchases, starting at $19.99 per month and MIDI Aid sells 1 in-app purchase, starting at $0.99 per month. Whichever you choose, the download price is not the number that matters.
SPL Graph ships an update every 6 months, MIDI Aid every 6 weeks. Both last shipped on November 13, 2026.
| Parameter | SPL Graph | MIDI Aid |
|---|---|---|
| Price | $9.99 | Free — better |
| Rating | 3.7 (3 ratings) — better | — |
| Positive reviews | 64.3% of reviews | — |
| Number of ratings | 3 — better | — |
| Update frequency | Every 6 months | Every 6 weeks — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Paid | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Mac |
| Requires iOS | 15.0 — better | 16.0 |
| Further details — not scored | ||
| Size | 30 MB | 41 MB |
| Age rating | 4+ | 4+ |
| Developer | Andrew Smith | Tobias Wissmueller |
In-app purchases
SPL Graph
- Remote Noise Monitoring7 Days trial$19.991 Month
- Remote Noise Mid Level7 Days trial$79.991 Month
- Remote Noise Large7 Days trial$149.991 Month
- Octave Band SPL Logging$9.99
- Video Capture Option$19.99
MIDI Aid
- MIDI Aid Pro7 Days trial$0.991 Month









