Spectrum Analyzer: Audio FFT

Spectrum Analyzer turns your phone microphone into a live audio FFT analyzer. Watch the frequency spectrum of any sound, then capture a 5-second average to see exactly which frequency is the strongest and how the energy is spread.

WHAT YOU SEE LIVE
• 32 frequency bands from 20 Hz to 20 kHz (2048-point FFT)
• Bars with peak hold, Line, Waterfall and Spectrogram views
• Peak frequency in Hz and peak level in dB
• Min / Max traces, cursor readout on any bar, freeze
• dB range adjustable from 30 to 120 dB

THE 5-SECOND CAPTURE
Tap Capture 5 s and keep the sound steady. You get a result card with:
• The strongest component in Hz (plus note and cents in Voice mode)
• The top three components and their levels
• How the detected energy splits between low, mid and high in the chosen range
• The strongest band level and the FFT resolution
Too quiet in the range? The card tells you, instead of showing a made-up peak.

BEFORE / AFTER
Save a capture as a reference, change something, capture again in the same mode and read the average dB difference. Keep up to 10 references and overlay one on the live graph.

THREE MODES
• Voice 80–4000 Hz with note name
• Machine 20–2000 Hz with 50/60 Hz mains hum and harmonics
• Room 20–500 Hz for low-frequency room modes

MORE
• CSV export of the live spectrum or a capture, text summary to share
• Calibration offset −20 to +20 dB (0.5 dB steps)
• Pink noise generator, unlocked for 24 hours with a short ad
• 30 languages

HONEST LIMITS
Levels are dBFS, relative to the microphone's full scale. A phone is not a certified sound level meter: use it to find frequencies and compare changes. Sound is analysed in memory and never saved as a recording.

Useful for tuning an instrument by ear, finding a boomy note in a room, checking a speaker, or tracking down a hum from a fan, fridge or transformer.

Recent changes:
Spectrum Analyzer+ now turns five seconds of live FFT data into a fixed result card with the dominant frequency, three strongest components, and low/mid/high energy. Save a card as a reference to compare the next capture in dB. Start and Capture now sit directly under the graph. Czech, Danish, Finnish, Hebrew, and Dutch interfaces are now complete.