Round two. You said the rhythm read as a heartbeat but the dub landed like punching a bag of sand — so the dub, and only the dub, has been rebuilt: higher, shorter, and with most of the noise taken out of it. The previous version is still here to switch to, so you can hear whether that actually fixed anything rather than take my word for it.
60 bpm throughout. The rate never varies — this gate tests the sound, not the measurement.
Each variant keeps playing until you stop it. Switching between them is seamless — the beat clock keeps running underneath, so an A/B never realigns the rhythm.
Play Lub-dub — revised and sit with it for three minutes — the length of a real session. Not analytically. The way you'd hear it if the app had just started. Switch to Lub-dub — previous whenever you want to check the dub against what you heard last time.
Judge independently. The criterion asks both of you to describe it without conferring first — one person's "well, sort of" becomes the other's answer the moment it's said out loud.
Switch between revised and previous and listen to the second sound of each pair. The revised dub sits higher (peak near 90 Hz rather than 75), is shorter, and carries about a third of the noise the old one did — the intent being a valve snapping shut rather than something landing in sand.
AC-6.2 — steady versus per-beat varying volume, judged blind. Neither of you preferred the varying version, and the criterion's own rule is explicit: if the varied version is not preferred, drop the modulation and simplify. It is gone, which is why there is no "living" variant on this page any more. Worth noting that this overturned a prediction you made in the register — that pairing volume with pulse strength would enhance the experience. Blind testing is how that gets caught.
AC-6.3 — one thump per beat or two. Both of you said two. Recorded, and the two-part lub-dub is what Stage 4 will build.
Re-asking a settled blind comparison would only invite an inconsistent answer, so those controls have been removed rather than left sitting there.
Three answers and a sentence each. AC-6.1 needs both verdicts to be "heartbeat" — if either of you says click track, that isn't a failed build, it's a finding: the sonification wants a different aesthetic direction, musical rather than literal, and far better learned tonight than after the pipeline exists.
Your answers stay in this browser only — nothing is sent anywhere. Copy them into the thread when you're done.
These are the numbers the sonification engine inherits if the sound is accepted — recorded here so the build doesn't start from a fresh guess.
| Element | Body | Onset | Decay | Level |
|---|---|---|---|---|
| S1 "lub" | 52 Hz falling to 38, bandpass Q 1.1, + noise | 0 ms | 150 ms | 1.00 |
| S2 "dub" (v1.1) | 88 Hz falling to 74, bandpass Q 2.6, noise 0.15 | 320 ms | 90 ms | 0.70 |
| S2 "dub" v1.0, superseded | 78 Hz falling to 58, bandpass Q 1.3, noise 0.45 | 320 ms | 110 ms | 0.48 |
| Metronome | 1.6 kHz highpassed click | 0 ms | 28 ms | 0.55 |
| Amplitude modulation | Removed — AC-6.2 came back "not preferred" from both listeners | — | — | — |
S2's level is set by ear-equivalent measurement, not by the number alone: a gain of 0.48 renders at 0.65 of S1's peak, because the higher bandpass passes more of the noise. At equal peaks the pair stops sounding like lub-dub and starts sounding like tick-tock, which is exactly the failure AC-6.1 is listening for.
Amplitude drifts; timing does not. Real pulse intervals also vary with the breath, but this gate holds the rate fixed on purpose, so that what you're judging is the sound rather than the liveliness of a simulation.