Adaptive Breath Switch — What It Does (Live) | (Source Code)

This is a standalone breath-controlled MIDI trigger. You blow into your microphone, and it sends a MIDI note on/off signal — turning your breath into a musical switch. It's designed for people with limited hand mobility who can't press keys or buttons. You can combine this feature with other features like gestural features or a web camera where you track the notes and then trigger the note with this component. 

Other pieces of software can include this switch.  Instead of sending notes it can be used to change presets so if you're playing a particular song and you want to be able to reach different notes you create a swapping of visual layout by blowing into the switch. An example is in the dial code that is set up. You could switch music scores. There are pieces of software here where you can use your cell phone gyroscope and move it up and down and then this for note triggering and then you can select notes a gesture of moving the phone or tilting the phone.

The Breath Engine

When you click Start Engine, the app accesses your microphone and runs the audio through a lowpass filter set to 30Hz — this isolates the slow, low-frequency energy of a breath or blow, ignoring speech and background noise. It measures the amplitude of that filtered signal and displays it as a bar meter on screen. When the level crosses the red threshold line, a MIDI Note On fires. When your breath drops back below the threshold (after a short hold-off delay to prevent flickering), a Note Off fires.

The Controls

A compact panel lets you tune four things: Gain (how sensitive the mic is), Threshold (how hard you need to blow to trigger), Velocity (how loud the MIDI note is), and Note-off Delay (how long it waits after you stop blowing before cutting the note — useful for holding notes smoothly).

The Keyboard

At the bottom sits a 3D-perspective piano keyboard. You can click or tap keys to send notes manually. There's also a Hover Mode — when switched on, simply moving your mouse over a key plays it, no clicking needed. You can set how many octaves are shown and which note it starts from.

MIDI Output

Like the other tools in this suite, it connects to a virtual MIDI port via the Web MIDI API, routing notes to your DAW or any software synth. There's a port selector, a rescan button, and a PANIC button that kills all sound on all channels instantly.

The Latency Strip

A small row of readouts shows trigger latency, note-on latency, and round-trip time in milliseconds — useful for fine-tuning your threshold to get the fastest possible response between breath and sound.