Binaural active headphones for precise localization

Binaural Active Earbuds: Breakthroughs in Sound Localization and Noise Isolation

Active earbuds suppress sudden loud noises and amplify faint sounds, protecting your hearing during gunshots, factory clamor, or hunting trips. Standard over-ear models feature closed-back designs with microphones on the outer cups. They pipe external sounds through the speakers in stereo, passively blocking noise up to 30 dB thanks to snug earpads and isolators.

The electronics instantly drop volume by 20–40 dB in milliseconds, boosting the speech spectrum for clear communication in noisy environments. But sound localization is limited: microphones in open air ignore diffraction off the outer ear, like a simplified dummy head without full HRTF.

Models with multiple directional mics offer quadraphonic sound, yet positioning accuracy still falls short without true binaural effects.

In-ear versions are compact but come up short:

• Noise isolation of 20–25 dB vs. 40 dB for over-ears;
• Limited features due to size constraints;
• Poor localization—mics outside the ear canal, with the housing blocking the outer ear.

Innovative Design with Binaural Microphones

The proposed design uses silicone replicas of the outer ear, mimicking cartilage acoustics. Electret mics are positioned at the entrance to the ear canal replicas (10 mm depth), capturing full HRTF with diffraction and canal geometry.

Sound is delivered via in-ear drivers with foam tips: +20 dB isolation, direct canal feed without foam filters. Frequency response spans 20 Hz–20 kHz with high fidelity; silicone vibration isolation minimizes housing noise.

Key differences from traditional designs:

• Mic at canal entrance (not inside, to avoid low/high-frequency distortion);
• Accounts for eardrum angle by aligning mic and driver;
• Acoustic tuning for flat frequency response without damping.

Prototypes nailed precise localization from any direction, even with scaled-down replicas (1 cm smaller). Performance hinges on component frequency response: nonlinear distortion kills binaural cues.

Recommended Components

For optimal frequency response:

Microphones:

• Panasonic WM-61: flat response, high sensitivity.
• PUI Audio AOM-5024L-HD-R: low distortion, ideal for binaural recording.

In-Ear Drivers:

• Sony MDR-EX15LP: flat response across the full range, with affordable alternatives.

Swapping in flat-response components boosts positioning accuracy, detail, and audible range.

Applications as a Binaural Recorder

The housing fits modules like memory cards and Bluetooth for smartphone pairing. In-ear drivers play back recordings with pinpoint spatial accuracy.

Key use cases:

• Tactical situations: edge in sound localization.
• Industrial settings: safety amid heavy noise.
• Audio production: concerts, VR content, acoustic testing.
• Hobbyist recording: vacations, events.

This design outshines competitors in isolation, detail, and versatility. Patented: RU217892U1.

Key Takeaways

• Binaural mics in ear replicas deliver full HRTF and pinpoint localization without distortion.
• In-ear drivers provide 40+ dB isolation and detail from 20 Hz–20 kHz.
• Quality depends on frequency response: go for WM-61, AOM-5024L-HD-R, Sony MDR-EX15LP.
• Dual-purpose: hearing protection + pro binaural recording.
• Prototypes validated the concept even with imperfect replica sizes.

— Editorial Team