Decibel X:dB Sound Level Meter 4+

Frequency Spectrum Analyzer

Thanh Dinh

Designed for iPad

    • 4.6 • 131.2K Ratings
    • Free
    • Offers In-App Purchases


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

"Decibel X" is one of very few noise meter apps on the market that has highly reliable, pre-calibrated measurements and supports dBA, dBC. It turns your iOS device into a professional sound level 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" 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
- Powerful calibration: Linear, Octave 1/1, 1/3, Load/save profile
- 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.
- InstaDecibel to capture your dB report overlaid on photos and easily shared via popular social networks (Facebook, Instagram, Messages, etc.).
- Support Live Activity, Dynamic Island
- Support both Portrait and Landscape layouts
- Beautiful, intuitive and carefully crafted UI design. Themes: LIGHT, DARK and CLASSIC


- Standard time weightings (Response Time): SLOW (500 milliseconds), FAST (200 milliseconds) AND IMPULSE (50 milliseconds)
- MIC Gain Offset from -50 dB to 50 dB
- Standard measurement range from 30 dBA up to 130 dBA
- HISTO graph for plotted history of the recorded values
- WAVE graph with 2 display modes: Rolling & Buffer
- 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


- 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.

* Privacy Policy:

What’s New

Version 9.8.0

Thanks for using Decibel X! Here's what's new for the version 9.8.0:
∿ Upgrade library components
∿ Several other minor improvements & bug fixes

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

Ratings and Reviews

4.6 out of 5
131.2K Ratings

131.2K Ratings

RealAdvisor ,

My mission and you might want to follow

Years ago I lost my high tones from being in the music business, competitive shooting and hunting without ear protection, whch at the time was something not known to me. My daughter and wife finally got exasperated with my asking “Huh, what did you say?” So they had me go to an audiologist who determined I did have significant hearing loss of the high tones, literally crashing off the chart. Having compensated for 19 years, it was time for hearing aids. For $6,000, great improvement shown. I’m due for new aids, another $6K. So, for the past 10 years I have spoken with some 50-60 young folks who blast music in their vehicles. I put the DecibleX app on my iPhone and demonstrate that they are ranging from the 90s to over 120 decibels. They were unaware of the damage they were causing to themselves and in some instances their children. Everyone has been nice and thankful that I’ve brought this to their attention and saved them their hearing and some $$$. Let’s pass it on!!!

Developer Response ,

We are glad 😀 that our Decibel X suits your needs. Hope you continue having decent experiences with us, and yes we love hearing more stories from you!

9235S ,

Great app!!

The free version is likely the best app of its kind, and highly recommended. The only strike against it is that the premium version is subscription based, and a fairly expensive one at $4.99 per month. I suspect that for most casual users, this is far too expensive…I certainly wouldn’t pay that. I can understand subscriptions for something like a newspaper or periodical magazine, where content is changing, but not for something that provides an essentially fixed functionality. This kind of app is particularly suitable to one time purchase of premium functionality.

Create a reasonably priced onetime purchase option If you keep a subscription, reduce the cost considerably. You may be surprised how many more paid users you’d have, if you do this.

Developer Response ,

Thank you for your kind words. We are glad that you like our App.
If you want to find the one-time paid version.
You can find "Decibel X PRO: dBA Noise Meter" on AppStore or via this link

treynolds57 ,

Very Good, With One Quibble...

I’ve used a couple sound meter apps over the last few years along with a commercial quality sound level meter. I would put this up there with the best of what I’ve used. This review is for the purchased, “pro” version of the software. That I can pay $4.99 and use the processing capabilities of my iPhone in leu of spending $150+ on a professional, stand-alone meter blows my mind.

The level of detail shown in the various portions of the screen offer a broad range of information to the user. You get both numerical and graph output as well as dial analog output of minimum and maximum readings, duration, etc.

One quibble is that when I pause the meter and reset it, it asks if I really want to, which is okay, but immediately restarts the sound reading, even if I don’t want it to. Also, I’d like for a reset to take the meter back to “0”. It restarts at the prior average. I would like to see these twin issues corrected, and I’d then give the app 5 stars.

App Privacy

The developer, Thanh Dinh, 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

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