BandPass
Real-time audio filtering with live spectrogram visualization
Download Free on Google Play
Real-time audio filtering with live spectrogram visualization
Download Free on Google PlayBandPass transforms your phone into a professional audio frequency analyzer and filter. Isolate specific sounds from background noise—perfect for diagnosing vehicle problems, troubleshooting machinery, analyzing audio recordings, or exploring the hidden frequencies around you. See and hear what you've been missing.
BandPass uses cascaded 4-stage biquad filters (48dB/octave rolloff) for surgical precision in frequency isolation. The same digital signal processing technology used in professional audio equipment, now in your pocket.
Drag interactive handles on the live spectrogram to select exactly which frequencies you want to hear. Everything outside your selection is silenced—isolate engine whines, bearing noise, or any specific sound instantly.
See sound as it happens with a scrolling frequency visualization. Logarithmic scaling highlights the full audible range from deep rumbles (20Hz) to high-pitched whines (15kHz+).
Save the bands you keep coming back to and name them — "car idle", "bearing whine", whatever the job is. Load one and you're straight back where you were, no re-dragging.
Record what you're hearing with no time limit, then play it back and adjust the filter live during playback—perfect for comparing "before and after" or sharing diagnostic findings with others. Import your own WAV files and run them through the filter too.
Boost what you hear up to 10x with the output gain, and brighten faint detail in the visualization separately with the display gain. Essential for detecting faint bearing noise, electrical whines, or distant mechanical sounds.
BandPass doesn't request the internet permission at all. It cannot phone home, cannot serve ads, and cannot upload your recordings — there's no network access to do it with. The filter, both visualizations and the full 20Hz-20kHz range are free; Pro is a one-time unlock, never a subscription.
Isolate engine knock, bearing whine, belt squeal, exhaust leaks, or electrical noise. Find the exact frequency of mysterious sounds to diagnose issues faster.
Identify compressor noise, fan bearing problems, or vibration frequencies in refrigerators, AC units, and machinery. Filter out ambient noise to focus on the problem.
Analyze recordings for unwanted hum, electrical interference, or specific frequency problems. Perfect for field recording troubleshooting and acoustic analysis.
Track down mysterious humming, buzzing, or vibration sources. Isolate HVAC noise, plumbing sounds, or electrical interference frequencies.
Analyze RF interference, power supply noise, or audio circuit issues. Visualize and filter specific frequency bands for troubleshooting and testing.
Explore the frequency spectrum of everyday sounds. Perfect for teaching acoustics, physics, or music theory with real-world examples.
There's a noise, and you can't tell what it is or where it's coming from. Your phone's mic plus a filter can pin it down. Here's the method.
Open the live spectrogram and let the noise play. A steady hum shows up as a bright, unmoving horizontal band — that's its frequency. Note where it sits.
Touch-drag a band-pass filter around that frequency and listen through your phone. Now you hear only the mystery noise, stripped of everything else in the room — which is how you confirm you've found the right sound.
Keep the filter on and walk around. The isolated noise gets louder as you near the source — the panel, the appliance, the duct, the fixture. A spectrum analyzer shows you the frequency; hearing it isolated is what lets you actually walk it down.
BandPass does all four: a live spectrogram and waterfall to find the frequency, and a touch-drag band-pass filter to isolate and hear it in real time — so you can identify what's humming and track down where. Get BandPass free on Google Play →
Open a live spectrogram and look for the steady bright band — that's the frequency. BandPass shows it in real time and lets you isolate it to confirm by ear.
Usually electrical — a ground loop, a transformer, a dimmer, or powerline noise, often with harmonics at 120 and 180 Hz. A low rumble under ~150 Hz is more likely HVAC or a motor.
Isolate its frequency with a band-pass filter and walk around listening — it gets louder near the source. Hearing only that sound is what makes it findable, and it's what BandPass adds over a graph-only analyzer.
Yes — BandPass lets you touch-drag a band-pass filter and hear only that range in real time, separating the noise from everything else.
Yes — isolate the rattle, whine, or hum's frequency to identify it and locate the source. It's built for automotive, HVAC, and building-noise diagnostics, not just audio production.
The real-time filter and both visualizations (spectrogram and waterfall) are free — no ads, no subscription. Custom presets and recording/playback are a one-time Pro unlock.
Tracking down a specific noise? These walk through the method step by step:
Like all ProDirt apps, BandPass follows our core principles: