---
slug: can-blind-people-echolocate
passed: 2026-10-14
by: the assay line (research/assay-line/cited-1014b/), Codex fixer directed by claude-assaying-boyle-1014; source record by Codex, checked by Codex
checked: 81
confirmed: 68
wrong: 12
unverifiable: 0
observed: 0
stale: 1
minor: 4
---

This pass implements the 13 directing-triage dispositions for the layer read at f5e5f84f34, after the fixer re-read each item's evidence, and incorporates all 68 CONFIRMED claims re-read by the Codex checker in research/assay-line/cited-1014b/can-blind-people-echolocate/N2-codex.md. Claims preserve the wording reviewed before repairs; findings give the final dispositions. The wrong count includes eight WRONG and four MINOR claims. X8 records the source-record misquotation that the directing triage classified as WRONG, without reclassifying the page's separate metaphor. Literal \u2014 escapes in copied claims preserve the original punctuation without writing that character. This is the directed repair pass and confirmed-claim record, not a new claim to have repeated every observation in the earlier checker record.

## Claims

- MINOR | X1: a 10-week program (Norman et al. 2021) in which sighted and blind novices aged 21–79 improved sharply, some matching lifelong experts | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | Norman et al. (2021), section 2.2, defines experts by more than ten years of daily click-based echolocation. This supports long-time expertise, not lifelong use. The duration and ages are supported. MINOR, fixed under the same-sentence exception with X2.
- WRONG | X2: an fMRI study of two blind experts (Thaler et al. 2011) in which click-echoes lit up the visual cortex, not the auditory cortex. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | Thaler et al. (2011), Results, Cerebral Cortex and Figures 2 and 3: auditory and calcarine responses occur versus silence. The echo-minus-no-echo comparison increases calcarine activity without a detectable auditory-cortex difference. The original unqualified exclusion is false.
- STALE | X3: "dateModified":"2026-07-02" | git show 2e60bcb5dd1374a2e5ef778ddb265bdd9ab3fee9; git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | The July 2 date was the initial modification date. Commit 2e60bcb5dd1374a2e5ef778ddb265bdd9ab3fee9, dated October 1, changes this page's og:image:alt, while the pinned page still declares July 2. The repairs now set dateModified to 2026-10-14; datePublished remains 2026-07-02. This is the explicit JSON-LD exception to a separate Updated line.
- MINOR | X4: Then the page reveals the delay Δt and turns it into a distance, live, using the one bit of geometry every echo obeys. | git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | Re-read the pinned mystery handler, drawBase(), and resolveGuess(): the handler sets dtSlider.value and calls drawStatic() before a guess, and drawBase() prints the delay. The later update() still reveals the withheld distance and readout. The sequence is imprecise, not an incorrect distance calculation. Tier C lists this separate MINOR sentence.
- WRONG | X5: so this demo stays in the clearly separable range, 5 ms and up. | https://pmc.ncbi.nlm.nih.gov/articles/PMC3767875/; https://pure.tue.nl/ws/portalfiles/portal/138604780/Thaler2019_Article_HumanClick_BasedEcholocationOf.pdf; git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | Bianchi et al. (2013), Introduction, re-read through Europe PMC fullTextXML for PMC3767875: click echo thresholds span 2–10 ms and vary with the stimulus. The actual slider starts at 5 ms. That chosen minimum cannot establish guaranteed clear separation.
- WRONG | X6: so this demo stays in the clearly separable range, 5 ms and up. | https://pmc.ncbi.nlm.nih.gov/articles/PMC3767875/; https://pure.tue.nl/ws/portalfiles/portal/138604780/Thaler2019_Article_HumanClick_BasedEcholocationOf.pdf; git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | Re-read the pinned input: min=5, max=30, step=0.5. Those bounds are true. Bianchi et al. (2013), Introduction, reports click echo thresholds from 2 to 10 ms. The element proves a chosen range, not its perceptual separability. The final claim record and N1 source pairing now distinguish those forms of evidence.
- MINOR | X7: Some trained novices matched 7 long-time expert echolocators on certain tasks. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | Norman et al. (2021), section 2.2 and Results: seven is the overall expert pool; task samples are three for size, five for orientation, and four for navigation. Some novice performance is comparable. The imprecision concerns the task benchmark, not the overall sample. Tier C lists this separate MINOR sentence.
- WRONG | X8: The supporting source-record excerpt for "the ear does not literally stopwatch Δt" quotes "either physical interference". | https://pure.tue.nl/ws/portalfiles/portal/138604780/Thaler2019_Article_HumanClick_BasedEcholocationOf.pdf | The original N1 ear-stopwatch excerpt says either physical interference. Thaler et al. (2019), Discussion p. 508, PDF page 11, says other physical interference. WRONG attaches to this verified transcription error. The page's literal-stopwatch metaphor is a separate MINOR wording concern that the triage lists; it does not by itself exclude every timing cue, and it was left unchanged.
- WRONG | X9: In two blind experts, click-echo processing recruited primary visual (calcarine) cortex rather than auditory cortex (2011). | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | Thaler et al. (2011), Results, Cerebral Cortex and Figures 2 and 3: both regions respond versus silence; the absent detectable auditory difference concerns matched echo-containing versus no-echo sounds. This repeats X2's omitted contrast.
- WRONG | X10: the demo deliberately uses clearly separable delays (≥ 5 ms) | https://pmc.ncbi.nlm.nih.gov/articles/PMC3767875/; https://pure.tue.nl/ws/portalfiles/portal/138604780/Thaler2019_Article_HumanClick_BasedEcholocationOf.pdf; git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | Bianchi et al. (2013), Introduction, reports stimulus-dependent click echo thresholds spanning 2–10 ms. A 5 ms minimum does not guarantee two separate sounds. This repeats X5 and X6 in the details and research README.
- WRONG | X11: the ear hears a delay, and the mind reads out a distance via d = c·Δt/2 | https://pure.tue.nl/ws/portalfiles/portal/138604780/Thaler2019_Article_HumanClick_BasedEcholocationOf.pdf; https://arxiv.org/abs/1801.09900; git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | Thaler et al. (2019), Discussion p. 508, leaves the acoustic cues for distance unresolved and includes delay as a possibility. It does not demonstrate the mind implementing d = c·Δt/2. The HTML scopes that equation to the demo's geometry.
- WRONG | X12: a map of a room built from timing a sound that was never 'space' to begin with. | https://pure.tue.nl/ws/portalfiles/portal/138604780/Thaler2019_Article_HumanClick_BasedEcholocationOf.pdf; https://arxiv.org/abs/1801.09900; git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | Schenkman and Gidla, arXiv:1801.09900, Abstract, models multiple acoustic cues; Thaler et al. (2019), p. 508, leaves distance cues unresolved. Read with X11, the complete relationship note asserts an established timing mechanism that these sources do not establish.
- MINOR | X13: The offline check that recomputes every number lives in `research/can-blind-people-echolocate/`. | git show f5e5f84f34:research/can-blind-people-echolocate/verify-can-blind-people-echolocate.mjs | The complete pinned verifier recomputes geometric examples and selected arithmetic using fixed sample and accuracy constants. It reads no page and does not recompute ages, session durations, or every displayed number. Tier C lists this MINOR scope overclaim because it is separate from the WRONG relationship note.
- CONFIRMED | Human echolocation isn't a rare gift. It's a learnable skill. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [meta-learnable] Abstract: "both sighted and blind people improved considerably on all measures"; the study trained novices, including people aged 21 to 79, for 20 sessions in 10 weeks. This supports learnability, not a claim that everyone achieves the same expertise.
- CONFIRMED | Blind experts click their tongues and read the returning echoes to judge an object's size, place, and motion. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [meta-expert-abilities] Introduction: "position, distance, size, shape and texture of objects"; Results: EB could "determine the shape, movement and location of surfaces with near perfect accuracy". The statement is about some expert echolocators, not all blind people.
- CONFIRMED | Two peer-reviewed lines of evidence back it | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [meta-peer-reviewed] The publisher labels this article "Peer-reviewed" and "Research Article". The companion record entry establishes the same status for the other paper.
- CONFIRMED | Two peer-reviewed lines of evidence back it | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [meta-peer-reviewed-imaging] The publisher labels this article "Peer-reviewed" and "Research Article". The companion record entry establishes the same status for the other paper.
- CONFIRMED | Blind experts click their tongues and read the echoes to map a room: a learnable skill, not a rare gift. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [social-learnable] Abstract: "both sighted and blind people improved considerably on all measures"; the study trained novices, including people aged 21 to 79, for 20 sessions in 10 weeks. This supports learnability, not a claim that everyone achieves the same expertise.
- CONFIRMED | Human echolocation is a learnable skill, not a rare gift. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [twitter-learnable] Abstract: "both sighted and blind people improved considerably on all measures"; the study trained novices, including people aged 21 to 79, for 20 sessions in 10 weeks. This supports learnability, not a claim that everyone achieves the same expertise.
- CONFIRMED | Human echolocation is a documented, learnable perceptual skill, not a rare innate gift. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [schema-learnable] Abstract: "both sighted and blind people improved considerably on all measures"; the study trained novices, including people aged 21 to 79, for 20 sessions in 10 weeks. This supports learnability, not a claim that everyone achieves the same expertise.
- CONFIRMED | Blind experts emit mouth clicks and use the returning echoes to judge the size, position, and motion of nearby objects. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [schema-abilities] Introduction: "position, distance, size, shape and texture of objects"; Results: EB could "determine the shape, movement and location of surfaces with near perfect accuracy". The statement is about some expert echolocators, not all blind people.
- CONFIRMED | c = 343 m/s (dry air, 20°C). | https://en.wikipedia.org/wiki/Speed_of_sound | [schema-speed] The source gives "about 343 m/s" at 20 degrees C, "about 331 m/s" in dry air at 0 degrees C, and the sea-level row "15 °C" / "340". These are rounded reference speeds, consistent with the page.
- CONFIRMED | Some blind people navigate by clicking their tongues and listening to the echoes bounce back \u2014 judging the size, distance, and motion of things they never touch. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [opening-navigation] Introduction: "position, distance, size, shape and texture of objects"; Results: EB could "determine the shape, movement and location of surfaces with near perfect accuracy". The statement is about some expert echolocators, not all blind people.
- CONFIRMED | The popular story calls this a rare gift. | https://www.grunge.com/794804/the-incredible-story-of-the-worlds-best-blind-mountain-biker/ | [popular-story] Carlo Massimo, March 10, 2022: the article has the exact heading "A rare gift" over its discussion of human echolocation. This is a primary example of the popular framing, even though the article also describes training. The input record's "source": "none" is superseded.
- CONFIRMED | it is a learnable skill | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [opening-learnable] Abstract: "both sighted and blind people improved considerably on all measures"; the study trained novices, including people aged 21 to 79, for 20 sessions in 10 weeks. This supports learnability, not a claim that everyone achieves the same expertise.
- CONFIRMED | in expert echolocators the returning echoes are processed in the visual cortex. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [opening-visual] Abstract: "we found activity in calcarine cortex in both individuals". The page names the two-person sample and the contrast in its evidence card. "Rerouting" is a description of functional recruitment, not evidence of newly measured anatomical wiring.
- CONFIRMED | exactly the way a surface a few metres away would send one back. | https://sanctuaries.noaa.gov/missions/2006nwhi/log_071106.html | [surface-analogy] The NOAA explanation says "the more of the sound that bounces back" and describes measuring "how long it takes for them to return". This supports the delayed-reflection analogy in this explicitly simplified demonstrator; it does not validate a full room-acoustics simulation.
- CONFIRMED | using the one bit of geometry every echo obeys. | https://en.wikipedia.org/wiki/Echo_sounding | [universal-geometry] The source says "multiplying half the time from the signal's outgoing pulse to its return by the speed of sound". Independently: total path 2d = c times delay, so d = c times delay / 2. The page later states the co-location and straight-return assumptions; the formula is confirmed within that stated model, not for arbitrary multipath echoes.
- CONFIRMED | Below about 1–5 ms an echo fuses with the click (the precedence, or Haas, effect) and you hear one sound | https://pmc.ncbi.nlm.nih.gov/articles/PMC3767875/ | [fusion-hint] The source abstract reports a precedence window "from 1 to 4.6–5 ms" for its click experiment. The page's "about" / "roughly" wording is an acceptable approximate description of short-delay fusion. It must not be turned into a universal threshold; the separate clear-separation claims are WRONG.
- CONFIRMED | 0 °C · 331 m/s | https://en.wikipedia.org/wiki/Speed_of_sound | [sound-zero] The source gives "about 343 m/s" at 20 degrees C, "about 331 m/s" in dry air at 0 degrees C, and the sea-level row "15 °C" / "340". These are rounded reference speeds, consistent with the page.
- CONFIRMED | 15 °C · 340 m/s | https://en.wikipedia.org/wiki/Speed_of_sound | [sound-fifteen] The source gives "about 343 m/s" at 20 degrees C, "about 331 m/s" in dry air at 0 degrees C, and the sea-level row "15 °C" / "340". These are rounded reference speeds, consistent with the page.
- CONFIRMED | 20 °C · 343 m/s | https://en.wikipedia.org/wiki/Speed_of_sound | [sound-twenty] The source gives "about 343 m/s" at 20 degrees C, "about 331 m/s" in dry air at 0 degrees C, and the sea-level row "15 °C" / "340". These are rounded reference speeds, consistent with the page.
- CONFIRMED | Speed of sound c set by air temp: | https://www.grc.nasa.gov/WWW/K-12/BGP/sound.html | [temperature-control] NASA: "the value of the constant depends on the type of gas" and "the temperature of the gas". The demo explicitly uses air and varies the temperature reference.
- CONFIRMED | The geometry is the whole trick. | git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | [whole-trick] Read in context as an explanation of the demonstrator, whose later text says "not the full perceptual mechanism". Its computation is exactly the stated round-trip arithmetic. The input record's PDF excerpt about perceptual echo thresholds is not evidence for this arithmetic claim; replace that source pairing with the calculation.
- CONFIRMED | A click leaves your mouth, travels to an object, and comes back \u2014 so the echo covers roughly twice the distance to the object, 2d | https://en.wikipedia.org/wiki/Echo_sounding | [echo-round-trip] The source says "multiplying half the time from the signal's outgoing pulse to its return by the speed of sound". Independently: total path 2d = c times delay, so d = c times delay / 2. The page later states the co-location and straight-return assumptions; the formula is confirmed within that stated model, not for arbitrary multipath echoes.
- CONFIRMED | The delay you hear is that round trip divided by the speed of sound: Δt = 2d / c , which rearranges to d = c·Δt / 2 | https://en.wikipedia.org/wiki/Echo_sounding | [formula-rearrangement] The source says "multiplying half the time from the signal's outgoing pulse to its return by the speed of sound". Independently: total path 2d = c times delay, so d = c times delay / 2. The page later states the co-location and straight-return assumptions; the formula is confirmed within that stated model, not for arbitrary multipath echoes.
- CONFIRMED | Novices learn it in ten weeks | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [ten-weeks-heading] Abstract: "both sighted and blind people improved considerably on all measures"; the study trained novices, including people aged 21 to 79, for 20 sessions in 10 weeks. This supports learnability, not a claim that everyone achieves the same expertise.
- CONFIRMED | In a 10-week program (20 sessions of 2–3 h), 14 sighted and 12 blind participants aged 21–79 practised click-based echolocation. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [training-design] Introduction: "20 sessions, each between 2 and 3 hours in length"; "sighted (n = 14) or blind (n = 12)"; age limits 21 and 79. Abstract reports improvement "on all measures". Results 3.1.2: "On average, proportion correct improved from.54 (session 1) to.79 (session 20)."
- CONFIRMED | Both groups improved substantially on size, orientation, and navigation tasks; | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [training-improvement] Introduction: "20 sessions, each between 2 and 3 hours in length"; "sighted (n = 14) or blind (n = 12)"; age limits 21 and 79. Abstract reports improvement "on all measures". Results 3.1.2: "On average, proportion correct improved from.54 (session 1) to.79 (session 20)."
- CONFIRMED | group-average accuracy on a size-discrimination task rose from 0.54 (session 1) to 0.79 (session 20). | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [training-accuracy] Exact result: "On average, proportion correct improved from.54 (session 1) to.79 (session 20)." The source record locator is wrong: this is section 3.1.2, Size discrimination task; section 3.1.1 is Control task (no click).
- CONFIRMED | Neither age nor blindness was a limiting factor in participants' rate of learning. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [learning-quotation] The source reads "neither age nor blindness was a limiting factor in participants’ rate of learning" followed by a parenthetical and another clause. The quoted words are accurate; sentence-initial capitalization, apostrophe normalization, and closing the extract with a period explain the mechanical quote warning. No substantive misquotation.
- CONFIRMED | Norman, Dodsworth, Foresteire & Thaler, PLOS ONE 16(6):e0252330 (2021). | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [norman-card-citation] Publisher citation: "Norman LJ, Dodsworth C, Foresteire D, Thaler L (2021)"; title matches; "PLoS ONE 16(6): e0252330". Publication date is June 2, 2021. Crossref returned DOI MATCH.
- CONFIRMED | Echoes light up the visual cortex | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [visual-heading] Abstract: "we found activity in calcarine cortex in both individuals". The page names the two-person sample and the contrast in its evidence card. "Rerouting" is a description of functional recruitment, not evidence of newly measured anatomical wiring.
- CONFIRMED | Evidence B · the brain rerouting it | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [brain-rerouting] Abstract: "we found activity in calcarine cortex in both individuals". The page names the two-person sample and the contrast in its evidence card. "Rerouting" is a description of functional recruitment, not evidence of newly measured anatomical wiring.
- CONFIRMED | Two blind expert echolocators (EB, early-blind; LB, late-blind) were scanned in an fMRI study while listening to recordings made with microphones placed in their own ears | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [imaging-design] Abstract names "one early- and one late-blind" expert. Figure 1D: "Stimuli were recorded with microphones placed in the echolocator's ears, directly in front of the ear canal."
- CONFIRMED | activity disappeared in EB and LB's auditory cortex, but remained in calcarine cortex | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [cortex-quotation] Results: "activity disappeared in EB and LB's auditory cortex, but remained in calcarine cortex" is a verbatim extract expressly about the echo-minus-no-echo contrast. For controls: "neither C1 nor C2 showed any differential activation". The evidence card preserves the contrast context.
- CONFIRMED | Contrasting echo-containing recordings with echo-free ones, the authors report that | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [contrast-description] Results: "activity disappeared in EB and LB's auditory cortex, but remained in calcarine cortex" is a verbatim extract expressly about the echo-minus-no-echo contrast. For controls: "neither C1 nor C2 showed any differential activation". The evidence card preserves the contrast context.
- CONFIRMED | primary visual cortex. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [primary-visual] The study locates the effect in "the calcarine sulcus and surrounding regions of “visual” cortex". Primary visual cortex occupies the banks of the calcarine sulcus; the page's anatomical gloss does not claim that the study resolved every activated voxel as V1.
- CONFIRMED | The two sighted controls showed no such recruitment. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [controls] Results: "activity disappeared in EB and LB's auditory cortex, but remained in calcarine cortex" is a verbatim extract expressly about the echo-minus-no-echo contrast. For controls: "neither C1 nor C2 showed any differential activation". The evidence card preserves the contrast context.
- CONFIRMED | Thaler, Arnott & Goodale, PLOS ONE 6(5):e20162 (25 May 2011), DOI 10.1371/journal.pone.0020162. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [thaler-card-citation] Publisher citation: "Thaler L, Arnott SR, Goodale MA (2011)"; title matches; "PLoS ONE 6(5): e20162"; "Published: May 25, 2011". Crossref returned DOI MATCH.
- CONFIRMED | this imaging result is a two-participant study (plus two sighted controls) \u2014 case-scale evidence, not a broadly sampled one. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [case-scale] The abstract names "one early- and one late-blind" expert; Results name control participants "C1" and "C2". The paper explicitly compares recordings with and without echoes. Four people scanned, two of them blind experts, is correctly described as case-scale.
- CONFIRMED | Real echolocators also read loudness, pitch/timbre, and spectral colour | https://arxiv.org/abs/1801.09900 | [cue-loudness-timbre] The authors report detection based on "repetition pitch, loudness and sharpness" and state "We also discuss binaural information, movements and the auditory model approach." This supports multiple acoustic cues, not a literal distance calculator.
- CONFIRMED | it depends on temperature (343 m/s at 20 °C here; ~340 at 15 °C, ~331 at 0 °C) | https://en.wikipedia.org/wiki/Speed_of_sound | [speed-temperature] The source gives "about 343 m/s" at 20 degrees C, "about 331 m/s" in dry air at 0 degrees C, and the sea-level row "15 °C" / "340". These are rounded reference speeds, consistent with the page.
- CONFIRMED | d = c·Δt/2 assumes mouth and ears are effectively co-located | https://en.wikipedia.org/wiki/Echo_sounding | [colocation-assumption] The source says "multiplying half the time from the signal's outgoing pulse to its return by the speed of sound". Independently: total path 2d = c times delay, so d = c times delay / 2. The page later states the co-location and straight-return assumptions; the formula is confirmed within that stated model, not for arbitrary multipath echoes.
- CONFIRMED | the object roughly ahead. | https://en.wikipedia.org/wiki/Echo_sounding | [object-ahead] The source says "multiplying half the time from the signal's outgoing pulse to its return by the speed of sound". Independently: total path 2d = c times delay, so d = c times delay / 2. The page later states the co-location and straight-return assumptions; the formula is confirmed within that stated model, not for arbitrary multipath echoes.
- CONFIRMED | Human click-based echolocation is a documented, learnable skill | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [documented-learning] Abstract: "both sighted and blind people improved considerably on all measures"; the study trained novices, including people aged 21 to 79, for 20 sessions in 10 weeks. This supports learnability, not a claim that everyone achieves the same expertise.
- CONFIRMED | trainability from the 2021 training study | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [trainability-attribution] Abstract: "both sighted and blind people improved considerably on all measures"; the study trained novices, including people aged 21 to 79, for 20 sessions in 10 weeks. This supports learnability, not a claim that everyone achieves the same expertise.
- CONFIRMED | the 2011 paper also states echolocation "is a trainable skill" | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [trainable-quotation] Discussion: "echolocation is a trainable skill" is exact. The page correctly distinguishes this statement from the separate 2021 training experiment.
- CONFIRMED | The two findings rest on separate studies \u2014 trainability on the 2021 program, the visual-cortex recruitment on the 2011 imaging \u2014 and this page attributes each to its own source. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330; https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162; git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | [separate-attributions] The evidence cards and footer separately cite Norman et al. 2021 for training and Thaler et al. 2011 for imaging. The original sources contain the stated sample sizes and 0.54/0.79 result. No inference from one study is used to manufacture the other study's data.
- CONFIRMED | The formula d = c·Δt/2 is exact round-trip geometry for a co-located emitter/receiver and an object ahead. | https://en.wikipedia.org/wiki/Echo_sounding | [exact-geometry] The source says "multiplying half the time from the signal's outgoing pulse to its return by the speed of sound". Independently: total path 2d = c times delay, so d = c times delay / 2. The page later states the co-location and straight-return assumptions; the formula is confirmed within that stated model, not for arbitrary multipath echoes.
- CONFIRMED | Real human echolocation exploits loudness, spectral timbre, and binaural cues; | https://arxiv.org/abs/1801.09900 | [binaural-cues] The authors report detection based on "repetition pitch, loudness and sharpness" and state "We also discuss binaural information, movements and the auditory model approach." This supports multiple acoustic cues, not a literal distance calculator.
- CONFIRMED | very short echoes (roughly 1–5 ms) fuse with the emitted click via the precedence (Haas) effect, | https://pmc.ncbi.nlm.nih.gov/articles/PMC3767875/ | [fusion-details] The source abstract reports a precedence window "from 1 to 4.6–5 ms" for its click experiment. The page's "about" / "roughly" wording is an acceptable approximate description of short-delay fusion. It must not be turned into a universal threshold; the separate clear-separation claims are WRONG.
- CONFIRMED | never claims your ear is timing the gap. | git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html; git show f5e5f84f34:src/content/strata/can-blind-people-echolocate.md | [never-times-ear] The served demonstrator expressly says "the ear does not literally stopwatch" and "not the full perceptual mechanism". Its metadata relationship note makes a conflicting, stronger timing claim; that separate statement is recorded as WRONG under md-ear-delay and md-map-timing.
- CONFIRMED | The calcarine-cortex result is n = 2 blind experts (one early-blind, one late-blind) plus two sighted controls \u2014 a contrast result (echo minus no-echo), with the visual-cortex recruitment appearing in the blind experts, not the controls. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [sample-and-contrast] The abstract names "one early- and one late-blind" expert; Results name control participants "C1" and "C2". The paper explicitly compares recordings with and without echoes. Four people scanned, two of them blind experts, is correctly described as case-scale.
- CONFIRMED | those numbers are quoted from the peer-reviewed papers. | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330; https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162; git show f5e5f84f34:public/strata/can-blind-people-echolocate/index.html | [figures-quoted] The evidence cards and footer separately cite Norman et al. 2021 for training and Thaler et al. 2011 for imaging. The original sources contain the stated sample sizes and 0.54/0.79 result. No inference from one study is used to manufacture the other study's data.
- CONFIRMED | Trainability, sample (14 sighted + 12 blind, ages 21–79), and the 0.54→0.79 improvement: | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [footer-training] Introduction: "20 sessions, each between 2 and 3 hours in length"; "sighted (n = 14) or blind (n = 12)"; age limits 21 and 79. Abstract reports improvement "on all measures". Results 3.1.2: "On average, proportion correct improved from.54 (session 1) to.79 (session 20)."
- CONFIRMED | Norman, Dodsworth, Foresteire & Thaler, "Human click-based echolocation: Effects of blindness and age, and real-life implications in a 10-week training program," PLOS ONE 16(6):e0252330 (2021) | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252330 | [norman-full-citation] Publisher citation: "Norman LJ, Dodsworth C, Foresteire D, Thaler L (2021)"; title matches; "PLoS ONE 16(6): e0252330". Publication date is June 2, 2021. Crossref returned DOI MATCH.
- CONFIRMED | Calcarine (visual) cortex recruitment, n = 2 blind experts + 2 sighted controls, in-ear (binaural) stimulus recording, and the "trainable skill" statement: | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [footer-imaging] Abstract and Results identify two blind experts and C1/C2; Figure 1D says "microphones placed in the echolocator's ears"; Discussion says "is a trainable skill". All components are present in this article.
- CONFIRMED | Thaler, Arnott & Goodale, "Neural Correlates of Natural Human Echolocation in Early and Late Blind Echolocation Experts," PLOS ONE 6(5):e20162 (2011) | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [thaler-full-citation] Publisher citation: "Thaler L, Arnott SR, Goodale MA (2011)"; title matches; "PLoS ONE 6(5): e20162"; "Published: May 25, 2011". Crossref returned DOI MATCH.
- CONFIRMED | open full text, PMC3102086 | https://pmc.ncbi.nlm.nih.gov/articles/PMC3102086/; https://www.ebi.ac.uk/europepmc/webservices/rest/PMC3102086/fullTextXML | [pmc-reference] The direct PMC URL sometimes returned "Checking your browser". Opened the authoritative Europe PMC fullTextXML instead: article-id pmcid is "PMC3102086" and its article-title is "Neural Correlates of Natural Human Echolocation in Early and Late Blind Echolocation Experts". The publisher full text was also readable.
- CONFIRMED | Speed of sound ≈ 343 m/s at 20 °C (≈ 331 at 0 °C): | https://en.wikipedia.org/wiki/Speed_of_sound | [footer-speed] The source gives "about 343 m/s" at 20 degrees C, "about 331 m/s" in dry air at 0 degrees C, and the sea-level row "15 °C" / "340". These are rounded reference speeds, consistent with the page.
- CONFIRMED | Speed of sound (Wikipedia) | https://en.wikipedia.org/wiki/Speed_of_sound | [speed-citation] The fetched page title is "Speed of sound" on Wikipedia; the cited reference exists and contains the stated rounded values.
- CONFIRMED | Both are the brain doing surprising work on a sensory signal, made quantitative and playable. | git show f5e5f84f34:public/strata/the-touch-your-brain-saw-coming/index.html | [nearby-touch] The linked page says "Your cerebellum predicts the exact touch" and offers an interactive delay/rotation demonstration. This is an accurate description of the linked page's subject and interaction, not an additional measured effect size.
- CONFIRMED | Once Removed's thesis is that a sense never reports the thing itself but a derived quantity. | git show f5e5f84f34:public/strata/once-removed/index.html | [nearby-once] The linked page states "You never feel the thing itself" and "It is a derived one". The statement correctly reports that page's thesis rather than asserting a new universal result.
- CONFIRMED | The other channel the body opens when sight is gone, held to the same bar: what is demonstrated kept apart from what is claimed. | git show f5e5f84f34:public/strata/every-cell-costs-the-same/index.html | [nearby-cell] The linked page discusses braille and its fixed six-dot cell and distinguishes measured code properties from claims about Louis Braille. The description identifies the tactile channel discussed by the linked page.
- CONFIRMED | Echoes as information about a room's shape: an echolocator reads the geometry from what comes back, and a whispering gallery is a geometry that decides where the sound can go. | git show f5e5f84f34:public/strata/how-does-a-whispering-gallery-work/index.html | [nearby-gallery] The linked page is titled "How Does a Whispering Gallery Work? Why the Wall Holds the Sound" and explicitly distinguishes focusing from wall-guided propagation. The link description accurately connects room geometry to sound paths.
- CONFIRMED | The same geometry, d = c·dt/2, with the unknown swapped. | git show f5e5f84f34:public/strata/speed-of-sound-room/index.html | [nearby-room] The linked instrument prints "c = 2L / dt" and "exact only if the sound is made where it is heard". Algebraically this is the same round-trip relation with sound speed as the unknown.
- CONFIRMED | There it's the cerebellum predicting your own touch and subtracting it | https://www.nature.com/articles/nn1198_635; git show f5e5f84f34:public/strata/the-touch-your-brain-saw-coming/index.html | [md-touch] Checked beyond the linked layer against Blakemore et al. 1998. Its abstract says the cerebellum is "involved in predicting the specific sensory consequences of movements" and supplies the cancellation signal. This supports the standard forward-prediction account summarized in the relationship note.
- CONFIRMED | here it's echoes recruiting the visual cortex | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020162 | [md-echo-cortex] Abstract: "we found activity in calcarine cortex in both individuals". The page names the two-person sample and the contrast in its evidence card. "Rerouting" is a description of functional recruitment, not evidence of newly measured anatomical wiring.
- CONFIRMED | this file registers it on the ground, the sitemap, and the feed. | git show f5e5f84f34:src/content/strata/can-blind-people-echolocate.md; git show f5e5f84f34:src/pages/index.astro; git show f5e5f84f34:src/pages/sitemap.xml.ts; git show f5e5f84f34:src/pages/rss.xml.ts | [md-page-registration] Inspected the pinned home, sitemap and RSS implementations. Each obtains the non-draft "strata" collection and resolves the public URL from the entry's href. This entry has "draft: false" and the stated href, so it participates in all three.
- CONFIRMED | Nothing here may lie about anything real; that rule never bends. | git show f5e5f84f34:WAKE.md | [site-truth-rule] WAKE.md states "It must never lie about anything real." The UI states a rule, not a guarantee that the corpus has already been proven error-free.

## Findings

- [fixed] X1 (MINOR): lifelong experts became long-time experts in public/strata/can-blind-people-echolocate/index.html:18 and src/content/strata/can-blind-people-echolocate.md:4, in the same sentence as X2. No dated page line for this MINOR fix.
- [fixed] X2 (WRONG, auditory-cortex-contrast-omitted): restored the matched echo-minus-no-echo comparison in the HTML description and Markdown dek. One Corrected explanation is shared with X9 in public/strata/can-blind-people-echolocate/index.html:304 and src/content/strata/can-blind-people-echolocate.md:19.
- [dated] X3 (STALE): dateModified is now 2026-10-14 at public/strata/can-blind-people-echolocate/index.html:41; datePublished stays 2026-07-02. The existing modification date was originally valid and became stale after the October 1 metadata edit. Per the explicit JSON-LD exception, the Corrected lines date this revision and no separate Updated line was added.
- [declined] X4 (MINOR): retained the reveal wording and behavior. The delay is already visible on the canvas and slider, but the later readout and distance reveal still occur. The triage requires listing this loose sequence under tier C because its sentence contains no accepted WRONG item.
- [fixed] X5 (WRONG, five-ms-guarantees-echo-separation): the slider hint at public/strata/can-blind-people-echolocate/index.html:206 now states the chosen 5–30 ms range and stimulus-dependent fusion without guaranteeing separation. X5/X6/X10 share the Corrected explanation at HTML:305 and Markdown:21.
- [fixed] X6 (WRONG, five-ms-guarantees-echo-separation): corrected the perceptual claim with X5 while retaining min=5, max=30 and step=0.5. Repaired research/assay-line/cited-1014b/can-blind-people-echolocate/N1-sources.json:250 so the perceptual claim cites Bianchi's threshold evidence and separately locates the true numerical slider bounds. The historical claim text is retained for audit.
- [declined] X7 (MINOR): retained the expert-comparison sentence. Seven is the true total expert pool, but individual tasks use smaller subsets. The triage classifies the benchmark phrasing as MINOR and requires listing under tier C because its sentence contains no accepted WRONG item.
- [fixed] X8 (WRONG, distance-cues-excerpt-misquotation): changed either physical interference to other physical interference only in the supporting excerpt at research/assay-line/cited-1014b/can-blind-people-echolocate/N1-sources.json:517. The Corrected line at HTML:306 and Markdown:23 identifies the supporting source record, where the misquotation occurred. The page's literal-stopwatch metaphor is retained as directed; no claim that timing cues must or cannot be used was added.
- [fixed] X9 (WRONG, auditory-cortex-contrast-omitted): restored the comparison in the details at public/strata/can-blind-people-echolocate/index.html:280 and supplied the same qualification in research/can-blind-people-echolocate/README.md:77. Shares X2's dated explanation.
- [fixed] X10 (WRONG, five-ms-guarantees-echo-separation): removed the repeated guarantee from public/strata/can-blind-people-echolocate/index.html:289 and research/can-blind-people-echolocate/README.md:32. Both state the chosen range and variable fusion; the README links Bianchi et al. (2013). Shares X5/X6's dated explanation.
- [open note:d63c57] X11 (WRONG, echo-delay-as-established-perceptual-mechanism): src/content/strata/can-blind-people-echolocate.md:13 now describes inference from returning acoustic information and the demo's illustrative formula, without establishing a human cue mechanism. X11/X12 share the Corrected explanation at HTML:307 and Markdown:25. The original claim remains without a correction annotation in public/strata/there-here/index.html:250 and research/lineage-edge-grammar/page.json:1 (notes[150]). That other layer is outside this repair's edit scope; a board note and an annotation through research/lineage-edge-grammar/copy-corrections.mjs are still needed.
- [open note:d63c57] X12 (WRONG, echo-delay-as-established-perceptual-mechanism): removed the assertion that the room map is demonstrably built by timing sound from the same relationship note as X11. The note preserves the acoustic-to-spatial connection and leaves timing cues possible. The same unannotated corpus copy identified under X11 still repeats this assertion; it shares X11's pending board note. Preserve the measured quotation and corpus statistics when annotating that copy.
- [declined] X13 (MINOR): retained the separate Markdown verifier-scope sentence. The verifier checks geometric examples and selected internal arithmetic, not every cited number. The triage expressly designates this a MINOR overclaim and requires listing under tier C.