Earbud Biometric Heart Rate Monitor Simulator & PPG Frequency Analyzer

● Live Optical PPG Waveform (530nm LED)

SR: 100 Hz λ: 530 nm HR: 135 BPM

Computed Heart Rate 135 BPM

Signal Quality Score 88.4%

Signal-To-Noise Ratio (SNR) 14.2 dB

Coupling Efficiency 94.0%

Peak Detector Lock State

Systolic systolic peaks reliably tracked

Locked High-Fidelity Signal

Photoplethysmography (PPG) in Hearables: Green light (530nm) emitted by the earbud reflects off pulsing arteriolar blood in the ear canal skin. Acoustic seal pressure prevents optical leakage and maintains steady contact with the tragus/concha capillary beds, isolating true cardiac pulses from running cadence shockwaves.

⚙ Sensor & Ear Canal Calibration

Target Heart Rate (Cardiovascular Demand) 135 BPM

Governs true cardiac cycle frequency ($f_{cardiac} = \text{BPM} / 60$) and systolic rise-time.

Ear Canal Seal Pressure ($P_{seal}$) 12.5 kPa

Acoustic coupling tightness in external auditory meatus. Optimal range 10–18 kPa ensures microvascular contact without localized blanching ischemia.

Movement Artifact Level ($A_{motion}$) 0.20

Harmonic stride and footstrike shockwaves transmitted through cartilage during running or HIIT jumps.

Respiration Modulation (Baseline Wander) 0.15

Low-frequency venous return respiratory sinusoidal fluctuation (0.2–0.35 Hz).

Biometric Testing Diagnostics:

Notice how dropping seal pressure below 6.0 kPa induces optical shunt leakage, dropping SNR below 6.0 dB and causing the peak detector to miss systolic pulses. Excessive workout motion requires firm ear tips to maintain lock.

Sampling Rate: 100 Hz Sensor: Green LED Photodiode