The biofeedback layer for wearables.
BioChord turns a wearable's heartbeat signal into real-time, adaptive sound that guides the nervous system toward calm. A drop-in engine you license and ship — not a system you build.
Resonance breathing, about six breaths per minute — the rhythm the engine gently tunes each listener toward.
Your device already measures the heartbeat. BioChord makes it do something.
Every wearable reports the same numbers — HRV, readiness, recovery. BioChord converts that passive metric into an active, daily intervention: adaptive sound that helps a user down-regulate stress in the moment. It's the engagement feature the hardware is missing, and a differentiator when every device measures the same thing.
From heartbeat to sound, in a closed real-time loop
BioChord takes a single input — the stream of intervals between heartbeats — and runs the full signal chain on-device, from physiological signal to generative audio and back to the listener.
Wearable PPG
Beat-to-beat intervals stream from any supported wearable over BLE.
Signal processing
Quality check, pulse detection and inter-beat-interval extraction.
HRV engine
Sliding-window analysis derives continuous heart-rate variability.
Layered Control Core
Parallel regulation across timescales with RSA phase-locked control.
Patent-pending coreAudio mapping
Control signals map to musical parameters — timbre, density, space.
DSP audio engine
A low-latency synthesiser renders the sound in real time.
Audio output
Adaptive biofeedback reaches the listener through headphones or speaker.
Closed feedback
The listener's changing physiology re-enters the loop, moment to moment.
The difference is in the core
Generic adaptive audio reacts to a heart-rate number. BioChord phase-locks the sound to the respiratory–cardiac rhythm itself, and drifts each listener toward their individual resonance frequency — the breathing pace where the autonomic nervous system responds most strongly. That closed-loop, multi-timescale control is the patent-pending heart of the engine.
A drop-in engine, not a feature to build
BioChord ships as a self-contained library with a clean interface.
Your team calls start() with your own
heartbeat-interval stream and has adaptive audio playing in a
single integration session — no DSP, no audio engineering, no
signal-processing team required.
Drop-in SDK
A single library with start(), stop(),
reset(). Stateless to initialise, stable public
interface, integrated in under a day.
Hardware-agnostic
The only input is a beat-to-beat interval time-series. If a device can expose it, BioChord runs on it — insulated from any wearable's SDK internals.
Licence-clean
Built exclusively from permissive components — Apache 2.0, MIT, BSD. No GPL, no copyleft. Ships with full third-party notices your legal team can clear fast.
Private by design
All processing runs on-device. No raw physiological data leaves the phone; only anonymised usage events. GDPR-compatible from the ground up.
Built on a decade of HRV-biofeedback research
Heart-rate-variability biofeedback — the mechanism BioChord automates — has a substantial peer-reviewed base for stress, anxiety and related outcomes. A selection of the literature:
HRV biofeedback improves emotional and physical health and performance
A systematic review and meta-analysis (Lehrer et al.) across a broad range of outcomes and populations.
View on PubMed →The effect of HRV biofeedback training on stress and anxiety
A meta-analysis (Goessl et al.) finding HRV biofeedback associated with reductions in self-reported stress and anxiety.
View on PubMed →RSA biofeedback on heart rate variability and PTSD symptoms
A pilot study (Zucker et al.) on respiratory sinus arrhythmia biofeedback — the phase relationship at BioChord's core.
View on PubMed →HRV biofeedback for substance use disorder: a randomized clinical trial
A recent RCT extending the evidence base for HRV biofeedback into clinical populations.
View on PubMed →BioChord is a wellbeing and performance technology. It is not a medical device and makes no diagnostic or therapeutic claims. Research is cited to describe the mechanism BioChord is built on, not to claim equivalent outcomes.
Built for the wearable ecosystem
BioChord is designed to sit on top of the devices people already wear, and inside the apps they already use. Any product that can stream beat-to-beat intervals is a candidate integration.
Turn a sensor into an experience
For device manufacturers, BioChord adds a daily-use feature on top of the heartbeat signal the hardware already captures — driving engagement and setting the device apart.
Live integrations run today on any device that streams beat-to-beat intervals; broader device support is on the roadmap.
Add a defensible wellbeing layer
For software companies, BioChord is a science-aligned feature you embed rather than build — reading whatever wearable your users already own.
Delivered to end users by our partners. BioChord licenses the engine; it does not sell an app of its own.
A licensable core, a clean foundation, patent-pending IP.
BioChord Software, Inc. is a Delaware C-Corporation with assigned intellectual property and a patent-pending signal-processing core. Built for licensing from day one, with a founding team spanning product, go-to-market and capital.
Frequently asked questions
What is BioChord?
BioChord is a licensable software engine that converts a wearable's heartbeat signal into real-time, adaptive audio biofeedback. It reads beat-to-beat heart interval data and generates generative sound that guides the listener's nervous system toward resonance breathing, roughly six breaths per minute.
How is BioChord different from generic adaptive audio that reacts to heart rate?
Generic adaptive audio reacts only to a single heart-rate number. BioChord phase-locks sound generation to respiratory sinus arrhythmia (RSA) — the coupling between breathing and heart rate — using a patent-pending, multi-timescale control core. This lets it drift each listener toward their individual resonance frequency rather than just tracking a number.
Is BioChord a medical device?
No. BioChord is a wellbeing and performance technology, not a medical device, and it makes no diagnostic or therapeutic claims. The cited research describes the underlying physiological mechanism, not guaranteed outcomes.
What wearables does BioChord work with?
BioChord is hardware-agnostic — its only required input is a beat-to-beat heart interval stream over BLE. Chest straps and fitness watches have live integrations today; smartwatches, smart rings, recovery bands, and other BLE heart-rate sensors are on the roadmap.
How long does it take to integrate the BioChord SDK?
Typical integration takes under one day. The SDK exposes a minimal interface — start(), stop(), reset() — and requires no in-house DSP or audio engineering team.
Does raw physiological data leave the device?
No. All signal processing runs 100% on-device. No raw heartbeat or physiological data leaves the wearable or phone, and the architecture is GDPR-compatible by design.
What scientific research is BioChord's approach based on?
BioChord automates the mechanism studied in HRV-biofeedback research, including a 2020 meta-analysis by Lehrer et al., a 2017 meta-analysis by Goessl et al. on stress and anxiety, a 2009 RSA-biofeedback pilot study by Zucker et al., and a 2025 JAMA Psychiatry randomized clinical trial on substance use disorder.
Who does BioChord license its technology to?
BioChord licenses its engine directly to businesses — primarily wearable manufacturers (chest straps, fitness watches, smartwatches, smart rings, recovery bands), and adjacent software platforms such as meditation and sleep apps, digital therapeutics, corporate wellness, and performance/recovery tools. BioChord does not sell a consumer app of its own.
Let's talk integration.
Request a live demo of the BioChord engine running on your device — and a walkthrough of what a licensing partnership looks like.