Spek Spectrogram analyzer

See your sound. Spek is a professional spectrogram analyzer and audio spectrum visualizer that reveals the hidden frequency composition of any audio file or live microphone feed — 100% offline, no uploads, no accounts.

Whether you are verifying a lossless FLAC rip, diagnosing a studio mix, or checking room acoustics, Spek translates complex sound waves into detailed, interactive frequency graphs right on your phone.

— KEY FEATURES —

ALL-FORMAT AUDIO INGESTION

Open WAV, FLAC, AIFF, MP3, AAC, OGG, M4A, and ALAC files. A built-in preflight inspector validates file headers, detects truncated or corrupted containers, and warns you before decoding begins. No crashes, no guesswork.

PRECISION FFT SPECTRUM ANALYSIS

Choose FFT sizes from 1024 to 8192. Apply Hann, Hamming, or Rectangular windowing to control spectral leakage. Adjust time-density overlap up to 95% for ultra-smooth frequency slices. Set custom dB ranges (-120 dB to 0 dB) to reveal faint background hums or isolate loud transients.

HARDWARE-ACCELERATED PERFORMANCE

Spek runs FFT calculations directly on your device silicon — Apple vDSP (Accelerate framework) on iOS and native KissFFT via NDK on Android. No virtual-machine overhead. No cloud processing. Fast rendering, low battery drain.

INTERACTIVE SPECTROGRAM VIEWER

Pinch-to-zoom and drag-to-pan across time and frequency axes. Toggle between Linear scaling (spot high-frequency compression cutoffs) and Logarithmic scaling (match human hearing for bass, vocals, and mids). A pre-baked 256-entry color LUT ensures instant palette swaps.

PLAYBACK-SYNCED ANALYSIS

Play your audio while viewing the spectrogram. A real-time playhead cursor tracks playback position, letting you visually pinpoint clicks, pops, transients, and noise floors at the exact moment they occur.

LIVE MICROPHONE SPECTRUM

Analyze room acoustics, vocal pitch, or frequency sweeps in real time. A continuous scrolling spectrogram displays live FFT output with absolute session-duration tracking. Audio data lives in a temporary rolling buffer and is discarded the instant you stop — never saved, never uploaded.

CHANNEL SELECTION & DOWNMIX

Analyze Combined Mono, Left-Only, or Right-Only channels independently. Spot stereo imbalances, panning errors, or channel-specific noise that a merged view would hide.

— WHO IS SPEK FOR? —

Music Archivists & Audiophiles — Verify true lossless quality. Spot fake FLACs or upsampled MP3s by checking for high-frequency cutoffs at 16 kHz vs. 22 kHz.

Audio Engineers & Mixing Professionals — Diagnose frequency balance, stereo phase issues, and unwanted resonances across the full spectrum.

Podcasters & Video Editors — Find hidden air-conditioning rumble, mic handling noise, or high-frequency hiss before publishing.

Sound Designers & Field Recorders — Inspect the full frequency range of captures and identify unusable noise floors.

Students & Educators — Visualize FFT concepts, windowing effects, and harmonic overtones in real time.

— SUPPORTED FORMATS —

WAV, AIFF, FLAC, MP3, AAC, ALAC, OGG Vorbis, M4A / MP4 audio

— PRIVACY & OFFLINE INTEGRITY —

100% offline processing — no internet connection required.

No account, no registration, no login.

No audio data ever leaves your device.

Files stored in a secure app sandbox; clear history anytime.

Microphone input is never recorded to storage.

Ad-supported via non-intrusive banners on non-analysis screens (GDPR & ATT compliant). The spectrogram viewer is completely ad-free.

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Download Spek and turn your phone into a professional-grade audio spectrum analyzer. See every frequency. Hear every detail. Trust every file.