Microphone-based breath detection sounds simple until you actually try it. Energy goes up, energy goes down — that's a breath, right? In practice, you run into continuous breathing with no silence gaps, noisy environments that drift over time, and (on iOS) a Web Audio API that silently returns all zeros. This post walks through how @shiihaa/breath-detection solves each of these problems.

The library was extracted from shii·haa , a breathwork and biofeedback app built by Felix Zeller, a Swiss physician (Intensive Care + Internal Medicine + Diplompsychologe). It's MIT-licensed, zero dependencies, and ships TypeScript types.

Installation

npm install @shiihaa/breath-detection

The Core Idea: Spectral Centroid for Inhale/Exhale Classification

Most breath detectors only measure when breathing occurs — they can't tell you whether a given phase is an inhale or an exhale.…