"Decibel X PRO" is one of very few sound meter apps on the market that has highly reliable, pre-calibrated measurements and supports frequency weightings: ITU-R 468, A and C. It turns your iOS device into a professional noise meter, precisely measures the sound pressure level (SPL) all around you. This extremely useful and beautiful tool will not only be a great tool for many uses but also bring you a lot of fun. Have you wondered how quiet is your room or how loud is a rock concert or sport event? "Decibel X PRO" will help you answer all of those.


- Trusted accuracy: the app is tested and pre calibrated for all Apple devices. The precision is matching with real SPL devices
- Apple Watch support: see noise level right from your wrist
- Frequency weighting filters: ITU-R 468, A, B, C, Z
- Powerful, smart history data management:
+ Recording data can be saved into a list of history records for future access and analysis
+ Each record can be exported as hi-res PNG graph or CSV text via sharing services
+ iCloud support which synchronize all history records across your Apple devices
+ Fullscreen mode to give overview the whole history of an record
- Dosimeter with NIOSH, OSHA standards
- FFT and BAR graphs to display real time FFT. Those are very useful for frequency analysis and musical tests. Real time predominant frequency is also displayed.
- WAVE graph with 2 display modes: Rolling & Buffer
- InstaDecibel to capture your dB report overlaid on photos and easily shared via popular social networks (Facebook, Instagram, Messages, etc.).
- Support both Portrait and Landscape layouts
- Beautiful, intuitive and carefully crafted UI design
- Optimized for iOS 11


- Standard time weightings (Response Time): SLOW (500 milliseconds) and FAST (200 milliseconds)
- Trimming calibration from -15 dB to 15 dB
- Standard measurement range from 30 dBA up to 130 dBA
- HISTO graph for plotted history of the recorded values
- Real time scale level chart
- Display Current, Average/Leq, and Max values with both nice and clear digital and analog layouts
- Quick reference text to help you compare with real-life examples
- "Keep Device Stay Awake" option for long duration recording
- Reset and clear current recording at any time
- Tap on Max value to reset at any time
- Pause/Resume the tool at any time


- Please do not expect a quiet room reading will be 0 dBA. The range 30-130 dBA is the standard usable range and an average quiet room will be about 30 dBA.
- Although all devices are pre-calibrated, custom calibration is suggested for serious purposes requiring higher precision and accuracy. You will need a real external device or calibrated sound meter as a reference, then adjust the trimming calibration until the reading matches with the reference.

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What’s New

Version 7.0.0

● Introduce a tab bar at the bottom and re-organize the layout accordingly
● Introduce a new minimal light theme and set the flat dark theme by default
● Fix an in-app purchase issue which caused some users to restore purchase every time opening the app
● Fix a crashing issue for PRO users when switching to "Modern Dark" theme
● Add support for running natively on Apple Watch. Decibel X will now measure directly using Watch's microphone instead of pairing results from phones
● Add support for the new iPad Pro
● Add show/hide usage tooltips button at the main screen
● Fixe BAR graph issue which shows incorrect frequency axes
● Remove the gap at the top and re-organize buttons
● Add left, right buttons to navigate among graphs
● Introduce fullscreen mode for graphs so that it is much easier to monitor measurements from distance
● Landscape mode now becomes fullscreen
● Re-organize settings to be more compact and convenient
● Various UI improvements to make the app clearer and intuitive
● A lot of performance improvements and bug fixes
● Component upgrades

Thanks for using Decibel X! Please be sure to rate this new version and leave us a review on the App Store. Your feedback is greatly appreciated. We're listening to your feedback and working hard to improving Decibel X.

Ratings and Reviews

4.6 out of 5
3.5K Ratings
3.5K Ratings

Stay away from the Dark (mode).

I’m just a hobbyist, so don’t need extreme accuracy. That said, previous apps I’d tried didn’t seem accurate, and compared to a handheld (actual) sound meter, usually weren’t. When I found the non-Pro app, it seemed spot on, and while the ads were ever present, they weren’t annoying (unlike another app that lets you use the trial version for 2 minutes and then stops working and puts up a “buy me” screen with an almost invisible close button). But after using the “free” version for a while, I decided this was worth it.

Everything was going fine up until this last update; I’d open it only to have the screen go completely black just after opening. Scrolling through apps would show that it was open, but it wasn’t there. I was pretty frustrated. So, I loaded on to my wife’s newer iPhone and it worked just fine. And then curiosity about the new “Dark Mode” got the better of me and I clicked it... and got nothing. I guess they named it better than they thought, as the screen goes completely dark.

As soon as they fix that problem, I’ll change my rating to 5 stars (if I can figure out how).

Developer Response ,

Hello, we are sorry for the bug. It has been fixed in the latest version now. Thanks.

Debauchee ,

Next to my D👀k and my Brain, my Ears are my Favourite Organ.

03NOV2018, I went to a Nine Inch Nails Concert in San Francisco, CA. The warm up act was playing so loud that it showed 122db Z Weighted!!! That is INSTANT Hearing Loss!!!👂 wearing my Ear Plugs under my shooting muffs, that only dropped the sound level 6db or to 117db
Z Weighted or Permanent Hearing 👂 after 20 seconds. I ran outside and during the break, confronted the sound crew, showing them the data and demanding the lower the volume else I’ll call OSHA and shut down the tour!!! The dropped it to 105db because of your program!!!

Later that week, I got a room upgrade due to noisy neighbours and I got a seat 💺 upgrade because the engines were too loud. I am PROUD to be a HEALTH-NAZI (for fun and profit) and you can be TOO!!!

MusicalMyers ,

Camera mode crashes the app... FYI

I’m a music and Theatre teacher, and just attended a conference, one session was on the need for hearing protection for music teachers. I panicked, bought some cheaper earplugs for the time being, set an audiology appointment, and purchased this app. I’ve only played with the app, for a few minutes and noticed that on the camera setting the app crashes. Seems like the developer is very responsive though, and is why I went through purchasing the app.
I’ve played on my piano for just a few minutes and was shocked that I can easily push my piano about 95 decibels! Yikes!
Guess, I’m glad I purchased the ear plugs...
and the app.


SkyPaw Co. Ltd
20.8 MB

Requires iOS 9.0 or later. Compatible with iPhone 5s, iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE, iPhone 7, iPhone 7 Plus, iPhone 8, iPhone 8 Plus, iPhone X, iPhone XS, iPhone XS Max, iPhone XR, iPad Air, iPad Air Wi-Fi + Cellular, iPad mini 2, iPad mini 2 Wi-Fi + Cellular, iPad Air 2, iPad Air 2 Wi-Fi + Cellular, iPad mini 3, iPad mini 3 Wi-Fi + Cellular, iPad mini 4, iPad mini 4 Wi-Fi + Cellular, 12.9-inch iPad Pro, 12.9-inch iPad Pro Wi-Fi + Cellular, 9.7-inch iPad Pro, 9.7-inch iPad Pro Wi-Fi + Cellular, iPad (5th generation), iPad Wi-Fi + Cellular (5th generation), 12.9-inch iPad Pro (2nd generation), 12.9-inch iPad Pro Wi‑Fi + Cellular (2nd generation), 10.5-inch iPad Pro, 10.5-inch iPad Pro Wi‑Fi + Cellular, iPad (6th generation), iPad Wi-Fi + Cellular (6th generation), iPad Pro (11-inch), iPad Pro (11-inch), iPad Pro (12.9-inch) (3rd generation), iPad Pro (12.9-inch) (3rd generation), and iPod touch (6th generation).


English, Dutch, French, German, Italian, Japanese, Korean, Portuguese, Simplified Chinese, Spanish, Traditional Chinese, Vietnamese

Age Rating
Rated 4+
© 2019 SkyPaw


  • Family Sharing

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

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