# Decibel X vs SPL Reference

The clearest difference is update cadence: SPL Reference at every 2 weeks against Decibel X's every 3 months. Decibel X's advantage is device support (3 vs 1). On price, ads, in-app purchases and iOS requirement there is nothing between them.

Both are free to download. Decibel X sells 5 in-app purchases, starting at $1.99 per 7 days and SPL Reference sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Decibel X ships an update every 3 months, SPL Reference every 2 weeks. The most recent releases landed on November 10, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | Decibel X | SPL Reference |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.6 (164K ratings)](https://appshunter.io/ios/app/decibel-xdb-sound-level-meter/id448155923/reviews)** | — |
| Number of ratings | **164K** | — |
| Positive reviews | 66.3% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 2 weeks** |
| Monetization | Freemium | — |
| Size | 90 MB | 6 MB |
| Requires iOS | 17.0 | 17.0 |
| Devices | **iPhone, iPad, Apple Watch** | iPhone |
| Age rating | 4+ | 17+ |
| Developer | [SkyPaw Co., Limited](https://appshunter.io/developer/1842040687) | [Direct Sound Records Ltd](https://appshunter.io/developer/1896279797) |

## What reviewers say

### Decibel X

[App page](https://appshunter.io/ios/app/decibel-xdb-sound-level-meter/id448155923)

This tool transforms your device into a professional sound level meter, offering precise measurements of ambient noise. It features advanced calibration, frequency analysis, and data management for various applications, from personal curiosity to professional use.

**Highlights:** Pre-calibrated sound pressure level (SPL) measurements, Frequency weighting filters (dBA, dBC, ITU-R 468), Apple Watch and Health App integration, History data management with export options, Dosimeter with NIOSH, OSHA standards, FFT and BAR graphs for real-time frequency analysis, InstaDecibel for sharing dB reports on photos

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support, iPhone Duo support

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly Membership | $1.99 | per 7 days |
| Monthly Membership | $5.99 | per month |
| Annual Membership | $49.99 | per year |
| ITU-R 468, A, B, C Weightings | $1.99 | one-time |
| Data Export | $2.99 | one-time |

**What reviewers like**

- ⭐ Excellent app
- 👍 Easy to use and understand
- 🔍 Useful for various applications
- 🎓 Helpful for hearing protection
- 🔧 Accurate and reliable

**What reviewers complain about**

- 💰 Expensive subscription model
- 🔒 Misleading free trial
- 📢 Intrusive ads
- 🤖 Inaccurate readings compared to professional meters
- 🤔 Confusing interface

**Reported bugs**

- App crashes when deleting recordings
- Microphone issues on certain devices
- Saved files not accessible after updates

**Requested features**

- Add GPS coordinates to recordings
- Improve reporting and data export
- Provide more weighting options
- Extend frequency range
- Allow music playback while using the app


### SPL Reference

[App page](https://appshunter.io/ios/app/spl-reference/id6806757498)

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Lifetime Professional Unlock | $39.99 | one-time |


## Frequently asked questions

### Is Decibel X free?

Decibel X is free to download, with in-app purchases available.

### Is SPL Reference free?

SPL Reference is free to download, with in-app purchases available.

### Do Decibel X or SPL Reference have ads?

Neither Decibel X nor SPL Reference shows ads.

### Which is updated more often, Decibel X or SPL Reference?

Decibel X ships an update every 3 months, and SPL Reference every 2 weeks. Most recently, Decibel X was updated on November 10, 2026 and SPL Reference on October 31, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*