Rev D · stethoscope insert
Take the chest wall out of the recording.
Heartware is a 45 gram insert that replaces the back plate of a stethoscope. It estimates the chest wall from the recording and divides it out. In bench recordings, the same murmur measured 1.73 dB apart through two chest walls; correction reduced the difference to 0.25 dB.
Fits 44, 46 and 48 mm heads. No adapter, no second device.
The bench numbers.
Bench and simulation. Each figure lists its sample size and method on the evidence page.
Wall thickness from the recording.
RMS error against the measured wall across 111 bench recordings. No tape measure, no second sensor, no input from the person holding the stethoscope.
The spread between two chest walls.
The same murmur through a 60 mm and a 110 mm wall in the bench model. Correction reduced the difference from 1.73 dB to 0.25 dB.
Contact gate.
Below 45 per cent contact the app returns no result. The take is refused.
How the correction works.
The chest wall behaves like a low pass filter. A thicker wall lowers the corner frequency, so the same murmur arrives quieter. The insert estimates that filter from the recording itself and divides it out. There is no second device and no calibration step.
A thick chest makes the same murmur quieter.
In the bench model, a grade 2 murmur arrives 1.73 dB apart through a 60 mm and a 110 mm chest wall. That is a third of the band a clinician listens in. Correction brought the same pair to 0.25 dB apart.
1.73 dB
uncorrected difference
0.25 dB
after correction
The recording app.
A six second take, one channel. The app shows the waveform, wall estimate, contact score and corrected level. It plays a generated murmur, so the interface can be tried without a device.
- 01Six seconds, one channel, 20 Hz to 2 kHz. The waveform is drawn as it arrives.
- 02The chest wall is estimated from the recording. No tape measure, no input from the person holding it.
- 03The murmur band is divided by the wall it just measured. The result is the corrected murmur level.
- 04Contact below 45 per cent returns no result. The take is refused.
A generated grade 2 murmur through a modelled chest wall, played in the browser. It shows the interface and runs itself. It does not measure you.
Price
$38.25Per unit, app included. No capital equipment, no consumable, no fee per exam. Materials and machining come in under that.
Next to what a clinic already buys. List price, February 2026.
- Heartware insert fits the head you own$38.25
- Eko CORE 300 digital stethoscope$199
- 3M Littmann CORE digital stethoscope$379
- Littmann 3200 digital stethoscope$449
Run a pilot, distribute, or license the design.
Each route starts with a small step: one pilot site, five demo units, or the design files under NDA.