Spectrum: Audio Analyzer & RTA

Spectrum turns your phone's microphone into a real-time audio analyzer, showing the exact frequency content of any sound as a live spectrum, a spectrogram, or a 1/3 octave RTA view, with a tone generator and calibration tools built in for real acoustic work.

WHAT YOU SEE, LIVE
The spectrum view plots frequency against level in real time, with log or linear scaling, adjustable peak hold, and A-weighting so readings match how the human ear actually perceives loudness. The spectrogram view lays that same signal out over time so you can see how a sound evolves, not just a single snapshot. A digital readout tracks the exact level and frequency wherever you tap the chart.

BUILT-IN TOOLS FOR REAL ACOUSTIC WORK
- A 1/3 octave RTA (real-time analyzer) view, the same band layout used in room tuning and sound system work
- A tone generator with sine waves, logarithmic sweeps, and white or pink noise, useful for testing speakers, tuning instruments, or checking hearing across a range
- A peak list showing the top frequency peaks in the current signal, tagged with their harmonic relationships, so you're not squinting at a chart to find a resonance or a hum
- Multiple tap markers on the chart at once, so you can compare several frequencies side by side instead of one at a time
- A calibration offset so readings can be adjusted to match a reference microphone or a known source
- A higher-resolution 16384-point FFT option for finer frequency detail when 4096 points isn't precise enough

SAVE WHAT YOU MEASURE
Freeze a reading, save the session, and export the data as CSV for further analysis, or export a standard image of the chart itself. History keeps every saved measurement with its full session data, not just a picture.

HONEST ABOUT WHAT THIS IS
Spectrum reads sound through your phone's built-in microphone, the same hardware used for calls, so its absolute accuracy depends on that microphone's own response. For casual room analysis, instrument tuning, speaker testing, or curiosity about the sound around you, it's a genuinely capable tool. For calibrated measurements against a legal noise standard, use dedicated measurement hardware.

FREQUENTLY ASKED QUESTIONS
Q: What's the difference between the spectrum view and the RTA view?
A: The spectrum view shows a continuous frequency curve at high resolution. The RTA view groups that same signal into 1/3 octave bands, the standard layout used in room tuning and live sound work, which is easier to read at a glance during setup.

Q: What does the tone generator actually do?
A: It plays a sine wave at a chosen frequency, a logarithmic sweep across a range, or white or pink noise, useful for testing speaker response, tuning instruments, or checking a room's behavior at specific frequencies.

Q: Can I use the microphone while the analyzer runs in the background or the screen is off?
A: The app is built around active, on-screen analysis rather than passive background logging, so keep it in the foreground while measuring for accurate results.

Q: Does Spectrum need an internet connection?
A: No. All analysis, generation, and calibration run locally using your microphone. An internet connection is only used for the optional high-resolution export feature.

Q: Will ads interrupt me while I'm actively analyzing sound?
A: No. The analyzer screen is treated as off-limits for interstitial ads. Banner ads, when shown, only appear on the history and settings tabs.

Q: What does Spectrum Pro unlock?
A: Pro unlocks the 1/3 octave RTA view, the tone generator, the peak list, multiple chart markers, the calibration offset, and the 16384-point FFT option, and it removes ads throughout the app.

SPECTRUM PRO
A single one-time purchase unlocks the full analysis toolkit and removes ads for good, with no subscription at any point.

Recent changes:
Performance and stability improvements.