Verdict: SonaVyx is the best free SPL meter app for professional use in 2026, providing IEC 61672 Class 2 compliance with A/C/Z weighting, octave band analysis, NC curves, and OSHA noise dose calculation. The NIOSH SLM app is the most scientifically validated option on iOS. Decibel X offers the best native mobile experience across both platforms.
Smartphone SPL meter apps have matured significantly. The best apps now implement IEC 61672 frequency weighting, support calibration, and provide octave band analysis. This comparison evaluates the top SPL meter apps based on standards compliance, accuracy, features, and professional suitability.
| Feature | SonaVyx | NIOSH SLM | Decibel X | dB Meter Pro | Sound Meter |
|---|---|---|---|---|---|
| Price | Free | Free | Free / $10 | $4 | Free |
| Platform | Browser (any) | iOS only | iOS / Android | iOS | Android |
| IEC 61672 Compliance | Class 2 | Validated | Partial | Partial | No |
| A/C/Z Weighting | ✓ | ✓ | ✓ | ✓ | A only |
| Fast/Slow/Impulse | ✓ | ✓ | ✓ | ✓ | ✗ |
| Leq Averaging | ✓ | ✓ | ✓ | ✓ | ✗ |
| Octave Band Analysis | ✓ (1/1 + 1/3) | ✓ (1/3) | ✓ | ✗ | ✗ |
| NC/NR Curves | ✓ | ✗ | ✗ | ✗ | ✗ |
| Calibration | ✓ (94dB ref) | ✓ | ✓ | ✓ | ✗ |
| Data Export | ✓ (CSV, JSON) | ✓ (CSV) | ✓ | ✓ | ✗ |
| Noise Dose (OSHA) | ✓ | ✓ | ✗ | ✗ | ✗ |
| Additional Tools | RTA, TF, RT60, STI, AI | ‗ | ‗ | ‗ | ‗ |
SonaVyx provides the most comprehensive SPL measurement capability of any app-based solution. Full IEC 61672 Class 2 implementation includes A, C, and Z frequency weighting with properly designed IIR biquad cascades from analog prototypes. Time weighting supports Fast (125 ms), Slow (1000 ms), and Impulse (35 ms attack, 1500 ms decay) per the standard. Metrics include Leq, Lmax, Lmin, Lpeak, SEL, and L10/L50/L90 statistical percentiles.
Unique among SPL apps, SonaVyx includes 1/1 and 1/3 octave band analysis, NC/NR/PNC noise curve comparison with automatic NC rating, 94 dB calibration support with per-frequency correction curves, and OSHA noise dose calculation. SonaVyx also provides RTA, transfer function, RT60, STI, and AI diagnostics \u2014 making it a complete measurement platform, not just an SPL meter.
The NIOSH Sound Level Meter app was developed by the US National Institute for Occupational Safety and Health and has been validated in peer-reviewed scientific studies. The NIOSH SLM provides calibrated SPL readings, 1/3 octave band analysis, noise dose calculation, and CSV data export. The app is free but iOS-only. It is the most scientifically credible SPL app for occupational noise assessment.
Decibel X offers a polished native app experience on both iOS and Android with A/C/Z weighting, calibration, and data export. The free version includes basic SPL measurement; the premium version ($10) adds octave band analysis. Decibel X provides a good balance of accuracy and user experience for general noise measurement.
dB Meter Pro ($4) is a straightforward iOS SPL meter with A/C/Z weighting, calibration, and clean display. It provides basic SPL measurement without the complexity of professional tools. Best for users who want a simple, affordable decibel reading on iPhone.
Sound Meter is a free Android SPL app providing basic A-weighted readings. It lacks calibration, C/Z weighting, and Leq averaging. Suitable only for rough noise level estimates, not professional measurement. For accurate Android SPL measurement, SonaVyx in the browser or Decibel X as a native app are better choices.
Choose SonaVyx if: you need professional SPL measurement with octave bands, NC curves, noise dose, calibration, and additional measurement tools (RTA, RT60, STI) in a single free platform that works on any device.
Choose NIOSH SLM if: you need the most scientifically validated SPL app for occupational noise assessment on iOS and want a tool backed by a government research institution.
Choose Decibel X if: you prefer a polished native mobile app experience on either iOS or Android with calibration and basic octave band analysis.
Choose a dedicated Class 1 meter if: you need regulatory compliance with traceable calibration certificates for occupational health, environmental noise permits, or building code verification.
Try It Now
Try SonaVyx SPL Meter \u2014 IEC 61672 Class 2, A/C/Z weighting, octave bands, NC curves. Free in your browser.