This app turns your iOS device into a professional sound level meter, detects halmful environmental noises, and helps protect your hearing and health.

"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
- Health App integration: export noise levels directly into Health app.
- 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.

If you like it or have suggestions, please support us by rating and giving us comments and feedback.

What’s New

Version 9.3.3

Thanks for using Decibel X! Here's what's new for the version 9.3.3:
∿ Fix an issue where summary report is not displayed
∿ Upgrade components
∿ Several improvements & fixes

What to expect in upcoming versions:
∿ Set notification alarm when exceeded a preset threshold
∿ Support external mics
∿ Hearing test

Ratings and Reviews

4.7 out of 5
5.5K Ratings

5.5K Ratings


Better than ever

I’m just a hobbyist, so I 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.

I’ve been enjoying the new features such as the frequency charting feature. Pretty cool seeing what frequency the drum beat is, or why band X seems so much louder despite being a lower decibel reading (more sound closer to 1500 Hz vs 300 Hz).

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!!!

B.J.S. ,

Best SPL App I’ve Used

This is the best SPL meter app I’ve used. Well worth the purchase.
The only suggestion I have is that it doesn’t rotate 180 degrees on the iPhone XS Max like it did on my old iPhone 6. I like to have the microphone at the bottom of the phone pointed at the speakers so to have the UI flip upside down was very useful.
Also the “email support” button in settings didn’t work when I pressed it. Hence my notes here. Otherwise it’s great and I use it in the theater everyday when setting up for a screening.

App Privacy

The developer, SkyPaw Co. Ltd, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Usage Data
  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

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

More By This Developer

You May Also Like