DuoBell PRO

🔔 DuoBell PRO — ANC-Busting Frequency Lab

Inspired by the real Škoda DuoBell — a bicycle bell engineered with 

University of Salford to penetrate Active Noise Cancellation headphones.

This interactive Web Audio experiment lets you explore WHY it works.

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⚙️ FEATURES

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🔔 Dual Resonator — two independent frequency oscillators (680–860 Hz + 900–1800 Hz)

〰️ Stereo Phase Drift — L/R channels with independent LFO detune, ANC cannot compensate both

🥁 4 Beat Patterns — DuoBell (irregular), Regular, Chaos, Triple

🏙️ Street Reflections — urban reverb with early wall reflections

🎯 ANC Simulator — toggle to hear what noise-cancelling actually removes

🚲 Doppler Effect — simulated bicycle pass-by with frequency sweep & stereo panning

🌌 Mr. Blin Cosmic Mode — synthwave space version with LFO warp & arpeggiated harmonics

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🧠 THE SCIENCE

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ANC works by analyzing sound via microphone and generating anti-phase waves.

The 720–800 Hz range is where most ANC algorithms struggle:

• Processing delay (~1–2ms) is comparable to the wavelength at 762 Hz

• Irregular intervals [320, 480, 330, 490...] prevent ANC from building a predictive model

• Stereo phase drift means L ≠ R — ANC cannot cancel both simultaneously

• Transient click (hammer strike) is too fast for ANC to react

Result: the bell is audible through Sony XM5, AirPods Pro, Bose QC45 ✅

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🎧 HOW TO TEST

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1. Put on your ANC headphones

2. Enable ANC mode

3. Press ▶ — try Regular pattern vs DuoBell pattern

4. Slide R1 into the 720–800 Hz zone (cyan glow = ANC zone)

5. Toggle ANC Simulator to hear what the algorithm removes

100% Web Audio API · No downloads · Works on mobile 📱

Built by Neon Void Studio

Inspired by Škoda DuoBell + University of Salford research