---
slug: doppler-siren
passed: 2026-10-14
by: the assay line (research/assay-line/queue-1014c/), Codex fixer directed by claude-assaying-boyle-1014; source record, fix check and repair by Codex
checked: 94
confirmed: 69
wrong: 23
unverifiable: 0
observed: 0
stale: 2
---

The fixer re-read the 21 directed triage findings against their cited sources and the layer at c8289bd340, corrected supported authored text and checks, and retained the 69 CONFIRMED claims re-read by the source checker. Repair checked the fix-checker's five problems and added four WRONG claims for the authored relationship notes in other layers. Counts are 69 CONFIRMED + 17 WRONG + 6 MINOR + 2 STALE = 94; the wrong field includes the 6 MINOR claims. The requested assay and correction date is 2026-10-14. Uncorrected film/poster captions and other-layer notes are open board notes; only the board can supply their note ids. The share-card finding is [fixed] under the landing rule: share card rebuilt at landing from the corrected dek. No image was regenerated in this pass. The generated verification placard is pending landing's rebuild under the explicit triage exception. Historical audio tests attributed to N2 were not rerun; current tests cover the physics, caption source, prerequisites and live page. The older psychological-memory assertions that overlap the rewritten shape explanation were replaced by physical descriptions, with no guessed explanation of what listeners remember.

## Claims

- WRONG | X1: The Pitch Doesn't Slide | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | Fowler describes a smooth off-path descent. fClosed and the increasing reception-time map are continuous for every allowed positive gap. Text titles corrected; original film and share-card pixels remain.
- WRONG | X2: A siren passing you doesn't glide down in pitch. | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | Fowler and Schwartz section 2 support a smooth drop. The page now says rapidly but smoothly for a close pass. The old opening also remains in rendered media.
- MINOR | X3: It holds one high note while it comes, drops fast right as it passes, then holds one low note going away. | https://www.lehman.edu/faculty/anchordoqui/lecture21-doppler.pdf | Schwartz qualifies the high note by distance. The opening now says nearly steady far before and after a close pass. Rendered captions and the share card were not regenerated.
- WRONG | X4: Two plateaus and a step \u2014 not a slope. | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | transitionDuration(10) = 0.8853990644379821 s; the closed form is smooth, not a discontinuity. The authored copy now describes a steep, smooth bend. The film still has the old step captions.
- WRONG | X5: Reproduce from a fresh checkout: research/doppler-siren/film/build.sh. | git show f5e5f84f34:research/doppler-siren/film/build.sh | The old renderer imported undeclared Playwright or machine-specific alternatives. The root manifest had only Astro and Acorn. The film now declares Playwright locally and documents Chromium, Node.js and encoder setup; prerequisite checks pass, but a full reproduction was not run.
- MINOR | X6: The pitch you hear is nearly flat and high for the whole approach, then falls through the source's true note in a rush, then is nearly flat and low. | https://www.lehman.edu/faculty/anchordoqui/lecture21-doppler.pdf; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | At 60 m the 10%-90% transition takes 5.3128671313392495 s. Nearly flat for the whole approach overstates the distant approximation; the page now qualifies distance and close passes.
- WRONG | X7: The bit nobody mentions | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm; https://www.lehman.edu/faculty/anchordoqui/lecture21-doppler.pdf | Fowler explicitly discusses retarded emission position and propagation delay. The heading is now The time sound takes.
- WRONG | X8: Push the “how close” slider out to 50–60 m and the truth comes back: a long flat high, a slow sag, a long flat low. | git show f5e5f84f34:public/strata/doppler-siren/index.html; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | At 30 m/s and gaps 50/60 m, the model gives 4.427189829330146/5.3128671313392495 s transitions in the six-second view. At 60 m its endpoints are 1078.485810753024/932.1627174823374 Hz, short of the limiting plateaus. The instruction now says the ends shorten.
- WRONG | X9: and the geometry (bunching ahead, stretching behind) is exact at any rate. | git show f5e5f84f34:public/strata/doppler-siren/index.html; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | sceneDraw uses different x/y scales and the smaller one for circular radii. At 700 by 230 pixels and 60 m the drawn spacing ratio is 1.4314994606256743, versus 1.191693290734824 physically; at 10 m the nearest-emitted ring reaches the drawn ear at 86.21407746772178 ms versus 29.154518950437318 ms. The drawing is now explicitly schematic.
- STALE | X10: Last verified 26 June 2026, when it was written. | git show f5e5f84f34:memory/log.d/2026-06-26T1108Z-doppler-siren-the-pitch-doesnt-slide.md; git show f5e5f84f34:research/verifier-independence/depends-dom-2.json; git show f5e5f84f34:research/verifier-independence/depends.mjs | The June run is historical. depends-dom-2.json contains both checks after successful baselines; depends.mjs filters to baseline exit code 0, and commit 4196cd8e31c dates that later record to 2026-08-01. This pass records fresh checks, but the generated placard is left to landing as triage directs.
- MINOR | X11: A graph of the pitch you hear over time. It is flat and high while the source approaches, drops steeply as it passes, and is flat and low as it recedes. | git show f5e5f84f34:public/strata/doppler-siren/index.html; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | buildCurve pushes continuously varying fClosed values. The accessible trace text now distinguishes close-pass near plateaus from a broader distant curve.
- WRONG | X12: A siren passing you doesn't glide down in pitch: it holds one high note while approaching, drops fast as it passes, then holds one low note going away. Two plateaus and a step, not a slope. | https://www.lehman.edu/faculty/anchordoqui/lecture21-doppler.pdf; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | The same continuous model contradicts the frontmatter no-glide and no-slope assertions. The dek is corrected; its earlier wording remains in the share card and thumbnail.
- MINOR | X13: A passing siren doesn't glide steadily down in pitch: it holds one high note while approaching, drops fast as it passes, then holds one low note going away. | https://www.lehman.edu/faculty/anchordoqui/lecture21-doppler.pdf; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | Schwartz qualifies distant approach. The phrase not steadily can reject constant-rate descent, but unqualified held notes needed nearly steady distant notes; metadata now includes that qualification.
- MINOR | X14: A passing siren holds one high note, drops fast, then holds one low note, not a steady glide. | https://www.lehman.edu/faculty/anchordoqui/lecture21-doppler.pdf; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | The close-pass approximation needed distance and nearly steady qualifications in Open Graph copy. The description now includes both.
- WRONG | X15: A passing siren doesn't glide: it holds high, drops fast, holds low. | https://www.lehman.edu/faculty/anchordoqui/lecture21-doppler.pdf; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | Continuous fClosed and monotone trOf contradict the categorical no-glide Twitter copy. The text now describes a rapid but smooth close-pass drop.
- WRONG | X16: It holds one high plateau while approaching, crosses its true frequency exactly at closest approach, and holds one low plateau while receding. | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | fClosed(teOfEar(0)) = 1007.7088454719099 Hz, not 1000 Hz, at physical closest approach. The 1000 Hz crossing is heard 29.154518950437318 ms later. Article metadata now distinguishes emission from reception.
- WRONG | X17: Its genuine Doppler-shifted tone, synthesised by retarded time (emit crests, propagate at 343 m/s, read what reaches the ear) plays while a pitch-versus-time graph draws itself into two flat plateaus (1096 Hz approaching, 920 Hz receding) with one fast step between, not a slope. | git show f5e5f84f34:research/doppler-siren/film/engine.mjs; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | Retarded-time synthesis and rounded limiting frequencies are supported, but transitionDuration(10) is 0.8853990644379821 s. VideoObject metadata now describes a steep, smooth bend.
- MINOR | X18: The closed form and a from-scratch wavefront count agree to 2.9e-8 over 6004 samples. | git show f5e5f84f34:memory/log.d/2026-07-17T0145Z-the-pitch-doesnt-slide-film.md; git show f5e5f84f34:research/doppler-siren/film/engine.mjs | wavefrontSamples(-3,3) creates 6004 intervals but only 6000 have midpoints in the comparison window. Their maximum relative error is 2.931869950249706e-8. The verifier counts comparisons and asserts exactly 6000; metadata and caption source agree. The rendered 6004 caption remains.
- STALE | X19: "dateModified":"2026-06-26" | git show f5e5f84f34:memory/log.d/2026-07-17T0145Z-the-pitch-doesnt-slide-film.md | The July 17 film log records a later page and VideoObject addition. The Article dateModified is now the requested revision date 2026-10-14; no separate page update line under the stated exception.
- WRONG | X20: (added) It is a step, not a slope | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm; git show f5e5f84f34:research/doppler-siren/film/engine.mjs; git show f5e5f84f34:research/doppler-siren/film/film.html | The caption denied a slope despite the smooth curve and finite 0.8853990644379821 s transition. Authored captions are corrected; the encoded film is NOT FIXED because rendering is prohibited.
- WRONG | X21: (added) While approaching, a steady high. While receding, a steady low. It crosses the source’s true note 1000 Hz exactly once, at closest approach, where the gap is, for an instant, not changing. | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm; git show f5e5f84f34:research/doppler-siren/film/engine.mjs; git show f5e5f84f34:research/doppler-siren/film/film.html | The graph axis is reception time. The crossing is heard at b/v, not at source closest approach. The authored caption now makes that distinction; the encoded film and poster are NOT FIXED because rendering is prohibited.
- WRONG | R1: The siren's pitch doesn't slide continuously | src/content/strata/the-compression-that-isnt-the-lens.md:15; research/doppler-siren/film/engine.mjs; https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | This authored relationship note repeats continuous-pitch-denied. At every allowed positive gap the model is continuous; Fowler describes a smooth off-path drop. The note is owned by another layer and remains open.
- WRONG | R2: the pitch holds two plateaus instead of sliding | src/content/strata/the-wake-that-broke-nineteen-degrees.md:14; research/doppler-siren/film/engine.mjs; https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | This authored relationship note repeats continuous-pitch-denied. The two frequencies are distant limits with a smooth transition between them; the note denies that transition. It is owned by another layer and remains open.
- WRONG | R3: A siren does not slide in pitch | src/content/strata/how-noise-cancelling-works.md:15; research/doppler-siren/film/engine.mjs; https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | This authored relationship note repeats continuous-pitch-denied. The model gives a rapid but smooth close-pass drop, with a 0.8853990644 s default 10%-90% transition. The note is owned by another layer and remains open.
- WRONG | R4: two plateaus and a step | src/content/strata/how-far-away-is-the-lightning.md:16; research/doppler-siren/film/engine.mjs; https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | This authored relationship note repeats continuous-pitch-denied without identifying a close-pass approximation. The model gives near plateaus and a steep, smooth bend for a close pass. The note is owned by another layer and remains open.
- CONFIRMED | N2 006: The siren is not faded between two notes. | git show f5e5f84f34:research/doppler-siren/film/make-audio.mjs | The audio source builds one carrier with harmonics from a common retarded phase; no crossfade between fixed siren frequencies.
- CONFIRMED | N2 007: It is synthesised by retarded time: emit crests, let them travel at 343 m/s, and read what reaches the ear, so the pitch bend you hear is the geometry of when each crest lands, not a formula applied to a tone. | git show f5e5f84f34:research/doppler-siren/film/engine.mjs | receivedPhaseArg solves the emission time whose wave reaches the ear and uses 2*pi*F0*te for phase.
- CONFIRMED | N2 008: Picture and sound share one verified engine; | git show f5e5f84f34:research/doppler-siren/film/film-facts.mjs | film.html and make-audio.mjs import the same engine. This pass checked code and physics only; N2 reported the earlier full audio checks.
- CONFIRMED | N2 010: Loudness and pan are declared craft; the frequency is the raw physics. | git show f5e5f84f34:research/doppler-siren/film/make-audio.mjs | The source declares amplitude envelopes and pan separately from the retarded phase.
- CONFIRMED | N2 012: Ahead of the source they pile up \u2014 each new crest is launched from a little closer to you, so they arrive bunched: a higher pitch. | https://www.acs.psu.edu/drussell/Demos/doppler/doppler.html | Russell shows forward compression and higher frequency; quantitative screen scale is addressed by X9.
- CONFIRMED | N2 013: Behind, they spread out: a lower pitch. | https://www.acs.psu.edu/drussell/Demos/doppler/doppler.html | Russell shows larger rear spacing and lower received frequency.
- CONFIRMED | N2 014: The source's own note never changes. Only the spacing you receive does. | https://www.acs.psu.edu/drussell/Demos/doppler/doppler.html | This is the fixed-F0 model, with the wailing-siren caveat explicitly stated.
- CONFIRMED | N2 016: The closer it passes, the sharper that fall \u2014 at a few metres it's almost a cliff; from far away it's a gentle ramp. | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | The angular formula and the engine give shorter transition durations at smaller gaps with fixed speed.
- CONFIRMED | N2 019: There's a delay built into hearing. | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | Fowler describes sound received from an earlier emission position.
- CONFIRMED | N2 020: The note that marks closest approach \u2014 the exact instant the pitch equals the siren's real pitch \u2014 leaves the source when it's directly level with you, but the sound still has to cross the gap to reach your ear. | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | At the perpendicular emission position the radial velocity is zero; its sound then travels the gap.
- CONFIRMED | N2 021: So you hear “the middle” a fraction of a second after the source is actually nearest you: a lag of exactly the gap divided by the speed of sound. | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | Substituting te=0 in trOf gives b/V exactly; this is the f0 crossing, not a claim about the arithmetic midpoint.
- CONFIRMED | N2 022: At 10 m that's 29 ms. | git show f5e5f84f34:public/strata/doppler-siren/index.html | 1000*10/343 = 29.154518950437318 ms, rounded to 29.
- CONFIRMED | N2 023: The dot is already pulling away by the time your ears report the turn. | git show f5e5f84f34:public/strata/doppler-siren/index.html | At t=b/V the model source has moved VS*b/V = 0.8746355685131195 m past the perpendicular point.
- CONFIRMED | N2 024: The check \u2014 every number here, recomputed live | git show f5e5f84f34:public/strata/doppler-siren/index.html | updateReadouts recomputes variable model values; fixed constants and offline cross-check figures are not rerun by the sliders.
- CONFIRMED | N2 025: The pitch you receive from a wavefront is set by how fast the gap to the source is changing when that wavefront leaves. In one line (v = speed of sound, vs = source speed, vr = how fast the gap is opening): | https://labs.phys.utk.edu/mbreinig/phys221core/modules/m12/doppler_effect.html | The radial velocity component is evaluated at emission, as the source formula and retarded-position discussion require.
- CONFIRMED | N2 026: f′ = f₀ · v / (v + vr) → head-on: f₀·v/(v−vs) · tail-on: f₀·v/(v+vs) | https://labs.phys.utk.edu/mbreinig/phys221core/modules/m12/doppler_effect.html | Set observer speed to zero and use radial opening speed in the denominator; the head-on and tail-on limits follow.
- CONFIRMED | N2 027: At your current settings (30.0 m/s, f₀ = 1000 Hz, v = 343 m/s): approaching 1095.85 Hz, receding 919.57 Hz, and exactly 1000 Hz at closest approach (the gap is momentarily not changing). | git show f5e5f84f34:research/doppler-siren/verify.mjs | The numbers are limiting frequencies. The 1000 Hz value refers to sound emitted at closest approach; the edited panel now makes this explicit.
- CONFIRMED | N2 028: The plateau ratio is 1.1917 = (v+vs)/(v−vs), a drop of 3.04 semitones | git show f5e5f84f34:research/doppler-siren/verify.mjs | The default ratio is 373/313 = 1.191693290734824 and the interval is 3.036155679871434 semitones.
- CONFIRMED | N2 029: and that ratio doesn't depend on how close it passes, only on the speed. | https://labs.phys.utk.edu/mbreinig/phys221core/modules/m12/doppler_effect.html | The asymptotic ratio (V+VS)/(V-VS) contains no pass distance; sound speed is fixed here.
- CONFIRMED | N2 030: The drop is not symmetric: +1.58 semitones up to the high plateau but only −1.45 down to the low one. | git show f5e5f84f34:research/doppler-siren/verify.mjs | The default upward and downward intervals round to +1.58 and -1.45 semitones.
- CONFIRMED | N2 031: The Hz spread above f₀ is wider than below. | https://labs.phys.utk.edu/mbreinig/phys221core/modules/m12/doppler_effect.html | The two offsets have denominators V-VS and V+VS; the upward offset is larger for a subsonic positive speed.
- CONFIRMED | N2 032: You hear closest approach 29.2 ms late \u2014 the gap (10 m) divided by v. | git show f5e5f84f34:research/doppler-siren/verify.mjs | The explicit propagation lag B/V gives 29.154518950437318 ms, rounded to 29.2.
- CONFIRMED | N2 033: The closed form above is checked against a second, independent method that knows nothing of it: a wavefront-counting simulation that just emits a crest every 1/f₀ seconds from the moving source, propagates each at v, and times the arrivals. | git show f5e5f84f34:research/doppler-siren/verify.mjs | simulate emits and propagates crests, then uses the reciprocal arrival gap; it does not call the closed form.
- CONFIRMED | N2 035: Both live in research/doppler-siren/verify.mjs \u2014 run it yourself. | git show f5e5f84f34:research/doppler-siren/verify.mjs | Both methods remain in one Node file. The new run passes with 6000 actual comparisons and maximum relative error 2.931869950249706e-8.
- CONFIRMED | N2 039: The physics was two plateaus all along. | https://www.lehman.edu/faculty/anchordoqui/lecture21-doppler.pdf | N2 confirmed the two distant limiting frequencies, not finite flat segments or a discontinuity. Edited prose now names those limits.
- CONFIRMED | N2 040: Idealizations, named: a point source in still air, no wind, no reflections or echoes, and the observer at rest (only the source moves | git show f5e5f84f34:public/strata/doppler-siren/index.html | The model has a point source, fixed listener, constant propagation speed and only the direct path.
- CONFIRMED | N2 041: moving-observer Doppler has a slightly different form, f′ = f₀(v+vo)/v, not used here). | https://labs.phys.utk.edu/mbreinig/phys221core/modules/m12/doppler_effect.html | For a stationary source and observer speed positive toward it, the source equation reduces to f0*(V+vo)/V.
- CONFIRMED | N2 042: Speed of sound taken as 343 m/s (dry air, 20 °C) | https://www.physicsclassroom.com/class/sound/Lesson-2/The-Speed-of-Sound | The cited teaching source gives approximately 343 m/s in dry air at 20 C.
- CONFIRMED | N2 043: it rises ~0.6 m/s per °C, which shifts the plateau Hz a little but not the shape. | https://www.physicsclassroom.com/class/sound/Lesson-2/The-Speed-of-Sound | The source gives an approximate temperature coefficient of 0.6 m/s per C over ordinary temperatures.
- CONFIRMED | N2 044: The rings you see are slowed | git show f5e5f84f34:public/strata/doppler-siren/index.html | The live page uses visualHz=7.5 rather than the 1000 Hz tone frequency.
- CONFIRMED | N2 045: a real 1000 Hz source emits a thousand crests a second, | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | A frequency of 1000 Hz is 1000 cycles per second; successive crests are 1/F0 seconds apart.
- CONFIRMED | N2 046: far too many to draw, so the visual crest rate is reduced for the eye; | git show f5e5f84f34:public/strata/doppler-siren/index.html | The visible ring rate is explicitly reduced in sceneDraw for legibility.
- CONFIRMED | N2 047: the audio uses the real f₀ curve, | git show f5e5f84f34:public/strata/doppler-siren/index.html | The oscillator follows heardAt on the physical frequency curve, with interpolation and a 5 ms target smoothing time.
- CONFIRMED | N2 049: The drop is given in equal-tempered semitones, 12·log₂(ratio), a convention for naming musical interval size, not a claim about perception. | https://www.sfu.ca/sonic-studio-webdav/cmns/Handbook5/handbook/Equal_Temperament.html | A semitone has frequency ratio 2^(1/12); solving for an interval gives 12*log2(ratio).
- CONFIRMED | N2 050: Real sirens often wail (sweep f₀ on purpose); | https://www.fedsig.com/sites/default/files/resource_library_document/91471146.pdf | The manufacturer documents a WAIL mode sweeping 725–1550 Hz.
- CONFIRMED | N2 051: here f₀ is held fixed so the Doppler shift is the only thing moving the pitch. | git show f5e5f84f34:public/strata/doppler-siren/index.html | F0 stays 1000 Hz; sliders change only source speed and gap.
- CONFIRMED | N2 053: This layer's check opens this page in a real browser and drives it. | git show f5e5f84f34:verify-doppler-siren.mjs | The browser verifier loads the page, inspects canvases and readouts, moves sliders and clicks play. Its current run passes 16 checks.
- CONFIRMED | N2 055: It is reading what you are reading. | git show f5e5f84f34:verify-doppler-siren.mjs | The verifier now serves this checkout’s authored public page, reading its DOM directly without a build.
- CONFIRMED | N2 056: verify.mjs is published, and it runs on its own: one file, and Node. | git show f5e5f84f34:research/doppler-siren/verify.mjs | N2 verified the published standalone copy at its pin. The corrected local file still needs only Node; refreshing the shared published mirror is outside this pass.
- CONFIRMED | N2 058: research/doppler-siren/verify.mjs | git show f5e5f84f34:research/doppler-siren/verify.mjs | The layer verifier exists and runs successfully. N2 checked its published citation; the shared mirror was not rewritten here.
- CONFIRMED | N2 059: verify-doppler-siren.mjs | git show f5e5f84f34:verify-doppler-siren.mjs | The named browser verifier exists and now uses portable paths and installed Playwright. No site build is required for the new run.
- CONFIRMED | N2 060: research/doppler-siren/film/build.sh | git show f5e5f84f34:research/doppler-siren/film/build.sh | The script path exists. The stronger clean-checkout promise is separately corrected under X5.
- CONFIRMED | N2 061: Top-down view: a source moves left to right along a road, emitting circular wavefronts that bunch together ahead of it and stretch apart behind it. A listener sits below the road. | git show f5e5f84f34:public/strata/doppler-siren/index.html | sceneDraw shows a left-to-right source, circular arcs and the listener below the road. Its alternative text now explicitly says schematic.
- CONFIRMED | N2 063: Companion film. A siren passes at 108 km/h and 10 m; its genuine Doppler-shifted tone plays while a pitch-versus-time graph draws itself into two flat plateaus with one fast step between. | git show f5e5f84f34:research/doppler-siren/film/engine.mjs | N2 accepted this as a close-pass visual approximation, not an actual step. The current alternative text now says near plateaus and a smooth bend; media remains unchanged.
- CONFIRMED | N2 064: 1096 Hzapproaching | git show f5e5f84f34:public/strata/doppler-siren/index.html | The high limiting frequency is 1095.846645367412 Hz, rounded to 1096.
- CONFIRMED | N2 065: 920 Hzreceding | git show f5e5f84f34:public/strata/doppler-siren/index.html | The low limiting frequency is 919.5710455764075 Hz, rounded to 920.
- CONFIRMED | N2 066: 3.04semitone drop | git show f5e5f84f34:public/strata/doppler-siren/index.html | 12*log2(373/313) rounds to 3.04.
- CONFIRMED | N2 067: both separate a sound's pitch from what's really changing \u2014 here the source moves, not the note | git show f5e5f84f34:src/content/strata/helium-voice.md | The related model separates source frequency from resonances; the Doppler model holds source frequency fixed. This is a comparison of the instruments, not a new claim about real helium inhalation.
- CONFIRMED | N2 068: another case where the pitch you hear isn't the pitch that's there | git show f5e5f84f34:src/content/strata/the-pitch-that-isnt-there.md | The related page deletes a fundamental while describing the perceived pitch that remains.
- CONFIRMED | N2 069: neighbours in the hearable-acoustics vein | git show f5e5f84f34:src/content/strata/critical-band-consonance.md | The related page is an audible instrument about consonance.
- CONFIRMED | N2 070: Its acoustic cousin: both are sound-timing instruments you drive by ear. | git show f5e5f84f34:src/content/strata/how-far-away-is-the-lightning.md | The related instrument uses the flash-to-bang delay to measure distance.
- CONFIRMED | N2 071: A sibling everyday-sound reversal built on the same constant, the speed of sound c = 343 m/s. | git show f5e5f84f34:src/content/strata/how-noise-cancelling-works.md | The related noise-cancellation implementation declares C=343, matching this model’s sound speed.
- CONFIRMED | N2 073: Move the source past your ear, watch the wavefronts bunch ahead and stretch behind, hear the exact Doppler-shifted tone, and watch the pitch-vs-time graph resolve into the truth. | git show f5e5f84f34:public/strata/doppler-siren/index.html | The authored page implements wavefronts, the frequency curve and audio controls; the wavefront picture is now explicitly schematic.
- CONFIRMED | N2 074: Every number recomputed live. | git show f5e5f84f34:public/strata/doppler-siren/index.html | The variable live readouts are recalculated on input; fixed film and verification figures are separate.
- CONFIRMED | N2 075: the real page is the interactive simulation at | git show f5e5f84f34:public/strata/doppler-siren/index.html | The frontmatter href points to the authored interactive HTML, which the browser check loads locally.
- CONFIRMED | N2 076: Send a source past a listener and watch the wavefronts compress ahead and stretch behind; hear the exact Doppler-shifted tone; | git show f5e5f84f34:public/strata/doppler-siren/index.html | The page draws wavefronts and feeds heardAt to its oscillator with numerical interpolation and smoothing.
- CONFIRMED | N2 078: The plateau ratio is exactly (v+v_s)/(v−v_s); | https://labs.phys.utk.edu/mbreinig/phys221core/modules/m12/doppler_effect.html | Dividing the two distant head-on/tail-on frequency limits gives the stated ratio.
- CONFIRMED | N2 081: Move the source past your ear and watch the wavefronts bunch up ahead and stretch behind; hear the exact Doppler-shifted tone; watch the pitch-vs-time graph resolve into two flat plateaus joined by a step. | git show f5e5f84f34:public/strata/doppler-siren/index.html | N2 accepted the old wording as a visual approximation. Current metadata explicitly describes near plateaus and a smooth bend for a close pass.
- CONFIRMED | N2 082: The drop is exactly (v+vs)/(v−vs), about 3 semitones at 108 km/h, and you hear the middle of it a propagation-delay after the source is actually nearest. | https://labs.phys.utk.edu/mbreinig/phys221core/modules/m12/doppler_effect.html | At 108 km/h the limiting ratio gives 3.036155679871434 semitones; the source-frequency crossing is delayed by b/V.
- CONFIRMED | N2 084: See the wavefronts bunch and stretch, hear the exact Doppler tone, watch the pitch trace resolve into two plateaus. | git show f5e5f84f34:public/strata/doppler-siren/index.html | The page supplies the wavefront illustration, Doppler audio and limiting-frequency guides; these are now qualified as near plateaus.
- CONFIRMED | N2 086: See the wavefronts, hear the Doppler tone, watch the two plateaus. | git show f5e5f84f34:public/strata/doppler-siren/index.html | The page supplies those controls and guides. This statement did not deny the finite transition.
- CONFIRMED | N2 087: A passing siren does not glide steadily down in pitch. | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm | The qualifier steadily rejects a constant-rate slide; smoothness alone does not imply a constant slope.
- CONFIRMED | N2 089: The plateau ratio is exactly (v+vs)/(v−vs); | https://labs.phys.utk.edu/mbreinig/phys221core/modules/m12/doppler_effect.html | The ratio is the exact quotient of the asymptotic limits in the stated subsonic model.
- CONFIRMED | N2 091: An interactive wavefront simulation, the real Doppler-shifted tone, and a live pitch-vs-time trace, with every number recomputed from the closed form and cross-checked against a wavefront-counting simulation. | git show f5e5f84f34:research/doppler-siren/verify.mjs | The interactive model and independent offline cross-check exist. The offline comparison checks defaults, not every live slider setting.
- CONFIRMED | N2 092: A siren at 1000 Hz and 108 km/h passes 10 m away. | git show f5e5f84f34:research/doppler-siren/film/engine.mjs | The film engine declares F0=1000, VS=30 m/s (108 km/h), and B=10 m.
- CONFIRMED | N2 095: Picture and sound share one verified engine. | git show f5e5f84f34:research/doppler-siren/film/film-facts.mjs | Both picture and audio import the shared engine. Current checking covers physics and caption source; N2’s earlier full audio results are not claimed as a fresh run.
- CONFIRMED | N2 099: (added) Doppler, 1842 | https://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm; git show f5e5f84f34:research/doppler-siren/film/film.html | Fowler dates Doppler’s account to 1842; the film source carries that attribution.
- CONFIRMED | N2 100: (added) 10% to 90% of the whole drop happens in 0.89 s: about 6% of the 16 s you watched. | git show f5e5f84f34:research/doppler-siren/film/engine.mjs; git show f5e5f84f34:research/doppler-siren/film/film.html | The model returns 0.8853990644379821 s in a 16 s film window, or 5.5337441527373885%, rounding to 0.89 s and 6%.
- CONFIRMED | N2 101: (added) "2 m → 0.18 s"; "5 m → 0.44 s"; "10 m → 0.89 s"; "30 m → 2.66 s"; "60 m → 5.31 s" | git show f5e5f84f34:research/doppler-siren/film/engine.mjs; git show f5e5f84f34:research/doppler-siren/film/film.html | Computed durations at 2,5,10,30,60 m round to 0.18,0.44,0.89,2.66,5.31 s.

## Findings

- [open note:efd864] X1: Authored titles now say A Close Pass, a Smooth Drop, but film.mp4 retains the false no-slide title. No film was rendered. Share-card title/dek copies are covered by X12's landing rebuild.
- [open note:efd864] X2: The opening and matching film source now say the drop is rapid but smooth for a close pass; the encoded film retains the no-glide opening. Share-card text is covered by X12's landing rebuild.
- [open note:efd864] X3: The authored opening now qualifies nearly steady distant notes before and after a close pass. The film/poster still use unqualified held-note captions. This remains MINOR, as triaged; share-card text is covered by X12's landing rebuild.
- [open note:efd864] X4: Authored step-without-slope assertions now describe a steep, smooth bend, including markdown and film source. The encoded film still denies a slope and the poster still calls it a step.
- [fixed] X5: Caption and build.sh name setup prerequisites; film/package.json pins Playwright 1.61.1, render.mjs uses it, and --check-prereqs checks Chromium launch and FFmpeg libx264/aac before media generation. Removed undeclared automatic package installation. Prerequisite check passes; full reproduction is not claimed.
- [fixed] X6: Replaced the whole-approach plateau description with nearly steady far-before/far-after notes for a close pass. No page correction line for this MINOR.
- [fixed] X7: Replaced the nobody-mentions heading with The time sound takes, and added the dated correction naming Fowler as counterevidence.
- [fixed] X8: Replaced the long-flat-ends instruction with the model-derived 4.43–5.31 s transition at 108 km/h and short ends in the six-second view.
- [fixed] X9: Kept the illustration and explicitly labelled it schematic in apparatus and accessible scene text; removed the exact-geometry claim and explained its unequal scales.
- [dated] X10: Preserved the original June verification as historical evidence and recorded this source pass plus the new physics/browser runs. NOT FIXED on the generated placard: triage explicitly reserves its rebuild for landing, and this task prohibits the shared writer. No Updated or Corrected line under the triage exception.
- [fixed] X11: The trace description now qualifies near plateaus for a close pass and describes a broader smooth curve for a distant one. No page correction line for this MINOR.
- [fixed] X12: Frontmatter title and dek state a rapid but smooth close-pass drop between nearly steady distant notes; share card rebuilt at landing from the corrected dek. This also resolves the title/dek copies from X1, X2 and X3 in public/og/doppler-siren.png and its thumbnail. No generator was run here.
- [fixed] X13: Added close-pass, distant and nearly steady qualifications to the meta description. No page correction line for this MINOR.
- [fixed] X14: Added the same qualifications to the Open Graph description. No page correction line for this MINOR.
- [fixed] X15: Replaced the categorical Twitter no-glide sentence with a rapid but smooth close-pass drop.
- [fixed] X16: Article metadata now states emission at closest approach and reception b/v later. The check-panel sentence and physics verifier also make the distinction explicit; the dated line notes the unchanged film/poster caption.
- [fixed] X17: VideoObject description now uses limiting frequencies and a steep, smooth bend while preserving the supported retarded-time synthesis account.
- [open note:efd864] X18: Authored counts now report 6000 actual comparisons, with exact-count assertions in verify.mjs and film-facts.mjs, matching metadata, film source and engine documentation. The encoded film still says 6,004 at 02:20. This remains MINOR, as triaged.
- [dated] X19: Article dateModified changed from 2026-06-26 to the requested revision date 2026-10-14. The WRONG correction lines already date this revision; no separate update line.
- [open note:efd864] X20: Authored captions now describe a steep, smooth bend and retain the measured finite duration. The encoded film still says it is a step, not a slope at 01:20; rendering is prohibited in this pass.
- [open note:efd864] X21: The authored reception-time caption puts the unique 1000 Hz crossing when sound emitted at closest approach arrives b/v later. The encoded film at 00:51-01:11 and poster.jpg retain the wrong crossing-time caption; rendering is prohibited in this pass.
- [open note:00b105] R1: On 2026-10-18 the relation note at src/content/strata/the-compression-that-isnt-the-lens.md:15 was changed to say the siren's pitch changes smoothly, with a rapid drop for a close pass, and that layer carries a dated Corrected 2026-10-18 line in its HTML and markdown. Still left: the preserved quotation of the old note in There, Here (public/strata/there-here/index.html:250 and research/lineage-edge-grammar/page.json:1, notes[1318]: "The siren's pitch doesn't slide continuously"), and, under this board note's wording, the unchanged clauses at src/content/strata/the-wake-that-broke-nineteen-degrees.md:14, src/content/strata/how-noise-cancelling-works.md:15 and src/content/strata/how-far-away-is-the-lightning.md:16, which R2-R4 below also hold under d5f510, fff4ab and 120b0a.
- [open note:d5f510] R2: src/content/strata/the-wake-that-broke-nineteen-degrees.md:14 still says the pitch holds plateaus instead of sliding. Replace that clause with a smooth change between distant high and low limits. Another layer owns this authored input; rebuilding Nearby alone preserves it.
- [open note:fff4ab] R3: src/content/strata/how-noise-cancelling-works.md:15 still says a siren does not slide in pitch. Replace that clause with a rapid but smooth close-pass drop. Another layer owns this authored input; rebuilding Nearby alone preserves it.
- [open note:120b0a] R4: src/content/strata/how-far-away-is-the-lightning.md:16 still calls the pitch transition two plateaus and a step. Replace that clause with near plateaus joined by a steep, smooth bend for a close pass. Another layer owns this authored input; rebuilding Nearby alone preserves it.

## Verification

- `node research/doppler-siren/verify.mjs`: passed; exactly 6000 comparisons, maximum relative error 2.931869950249706e-8, checked against the page's 3e-8 bound.
- `node verify-doppler-siren.mjs`: 16/16 checks passed on this checkout's authored page, including readouts, slider behaviour, canvas content and three viewport widths.
- `node research/doppler-siren/film/film-facts.mjs --physics-only`: 25/25 passed. Audio checks deliberately skipped; no audio was generated or remeasured.
- `bash research/doppler-siren/film/build.sh --check-prereqs`: passed; installed Playwright 1.61.1 launches its matching Chromium, and FFmpeg lists libx264 and aac encoders. No full render or reproduction was attempted.
- The fixer's syntax checks passed. Repair reran the physics, browser and film-source checks above successfully. The claims gate rejects the 11 required PENDING findings until board ids are supplied; the em-dash gate names only another layer. The original edit ledger is in `research/assay-line/queue-1014c/doppler-siren/fix-report.md`; current gate results and the repair audit are in `research/assay-line/queue-1014c/doppler-siren/repair-report.md`.

## Not done

- No film, audio or image generation or re-encoding. The rendered title/no-slide captions, step captions, crossing-time caption and 6004 count persist in `public/strata/doppler-siren/film.mp4`; the step, plateau and crossing-time captions persist in `poster.jpg`. These remain open. The share card is handled by landing from the corrected title and dek; its current pixels were not changed here.
- No generated placard edit, shared verifier-mirror refresh, shared search/index rebuild, site build, package installation, or change to another layer. The placard still says 26 June; the shared published verifier may still carry its earlier labels until landing rebuilds it.
- R1-R4 remain in the four other-layer authored relationship notes.