RTA SPL - Audio Analyzer Pro

Assessing a sound level or diagnosing a spectral imbalance normally requires a separate sound meter and spectrum analyzer, often expensive or imprecise on mobile — this audio analyzer combines both functions in a native Rust computing engine, with no garbage-collection latency.

Who is it for, and in what situations?
For a live sound engineer, the audio analyzer lets you fine-tune an equalizer by comparing the measured curve to a target curve (Harman, JBL House) and pinpoint the exact frequency of feedback using the high-resolution mode. For a car audio technician, the app offers dedicated calibration curves (Audiofrog, B&K Optimum, Step-Down) to tune the frequency response of a vehicle cabin. For a health and safety officer, the SLOW/FAST history with NIOSH/OSHA thresholds helps document prolonged noise exposure.

What you gain
- Spot a tonal imbalance at a glance thanks to the colored spectral tilt line
- Assess listening fatigue in a mix thanks to psychoacoustic sharpness (ACUM, Zwicker model)
- Calibrate an audio system with precision thanks to target curves and their ±3.5 dB tolerance corridor
- Track noise exposure over time thanks to L10/L50/L90 statistics and LRA
- Catch clipping instantly thanks to real-time saturation detection

Key Features
📊 RTA spectral analysis
- IIR constant-Q filter bank, resolution from 3 to 24 bands per octave
- Live spectral centroid and bandwidth display
- Sharpness (ACUM) overlay on high frequencies
🎚️ Professional SPL measurement
- A-weighting compliant with IEC 61672, FAST (125 ms) and SLOW (1 s) integration
- VU meter with color-coded safety zones and clipping badge
- Time history, histogram, and L10/L50/L90 percentiles
🎯 Calibration and target curves
Reference curves: Harman, Audiofrog, JBL House, B&K Optimum, Half Whitledge
- Two dynamic range modes: Studio (30–100 dB) and Live (50–120 dB)
- Manual microphone calibration (RTA offset, SPL offset)
📘 Built-in learning
- Explanatory tooltip on every parameter (theory, typical values, use cases)

A differentiating technical approach
Unlike tools that rely on a fixed-resolution FFT, this audio analyzer uses a constant-Q filter bank (CQT), which better matches human frequency perception. The constant-Q transform delivers better resolution in low frequencies than a classic FFT, whose resolution stays fixed regardless of where in the spectrum you're analyzing — a decisive advantage for precisely identifying a room mode or an EQ issue in the bass range. The signal processing engine, written entirely in Rust, avoids the garbage-collector latency found in competing apps built in Java or Dart.

Your data, your choice of use
The app accesses the microphone solely for acoustic analysis, with no other access to personal data. The free version remains fully functional (3/6-band RTA, complete SPL measurement); advanced features (24-band resolution, Pro curves, Live mode) are unlocked via a 30-minute rewarded video ad or a one-time lifetime purchase, with no subscription.

Install this audio analyzer to measure, calibrate, and understand the sound behavior of your environment starting with your next session.