Sonic — micro analysis of prose as heard composition

Status: rough spec (direction). Nothing here ships until scheduled. No new force, no new stored field, and no new canonical state is proposed: every quantity below is a reading of prose that already exists in the record (a scene's prose, its BeatPlan, its BeatProseMap). Where a formula is stated it is a candidate, and every constant is a dial to be calibrated, never a theorem.

Priority: the value-add, second behind the causal simulator itself (specs map). A simulator that models only what happened is not enough to rehearse a situation in; it must carry what it felt like while it happened — the pause, the tone, the pressure — and this is the micro layer (Words → Rhythm → Sound → Emotion → Perception) under the macro one the pentad already measures (World → Forces → Causality → Consequences).

Micro is in service of macro (2026-09-20). The micro layer is not a peer research programme. Its job is engagement — holding a reader's attention on the scene — and conveying the macro movement (what the world did) so that a computed consequence is felt rather than reported. Its north star is therefore engagement dynamics: the push and pull of attention across a scene — tension and release, withholding and disclosure, an open question pulling forward and a consequence pushing back — a candidate eastern ontology of complementary forces (yin/yang) at the grain of prose, mirroring the feed/bound cycles the pentad already has at macro grain. The western music ontology below is one candidate instrument for reading those dynamics, kept because it names the reader's inner hearing precisely; it is not the north star. Any measure proposed here is graded by one question: does it improve how well the screen carries the board (strategy 14 §1a and Track G).

The idea in one line, from the founder (2026-09-18):

Meridians has mastered macro delta analysis; it has not touched micro prose beauty. Authors are textual musicians. Each scene (~500 words) is a composition, and the bridge from delta extraction to micro elegance is music theory — the sounds we produce in our head while we read.

Authority: the pentad spec owns the five forces and their measures; this spec owns the finer grain beneath them and must not redefine a force. Positioning owns what may be said publicly: the sonic layer is direction, never capability.

Read first: pentad §7.8 (grain), src/lib/core/constants/scale.ts (WORDS_PER_BEAT, SCENE_UNIT_WORDS), src/types/domain/beat.ts (BeatFn, BeatMechanism, BeatProseMap), src/lib/core/io/sentence-tokenization.ts (splitIntoSentences).

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1. Two grains — what Meridians does and what it cannot yet do

Every macro measure is a function of the per-scene force snapshot; the activity curve has one point per scene and the classifiers (Legendre spectrum, ×2.5 ladder, growth exponent β, turnover τ) decompose that one curve. This is why the classifiers are elegant and also why they saturate: four reads of one signal. The honest limit is stated in the pentad and positioning contracts. The sonic layer is the second signal.

1.1 The macro classifiers — how elegant, and what is missing

Shape, scale, density, and pacing are each one stated rule with named dials, and each is orthogonal in form (spectrum, ladder, exponent, turnover). They are not orthogonal in input: shape and pacing read the same activity curve, scale and density read the same scene count. A record therefore has two independent macro coordinates and four labels. The record already computes quantities that would add genuinely new axes; classifying them is the obvious next macro step, and none requires new data:

Each is a delta-grain measure and belongs in the pentad spec's classifier ledger, not here; they are listed so the boundary is clear: every one of them is still macro. None hears the prose.

The two grains meet at the beat: the plan says what each ~100-word beat must do (BeatFn) and how it is delivered (BeatMechanism); the prose realises it; macro reads the scene's structural delta; sonic reads the passage's sound. Same object, two ears.

2. The hierarchy — music nested in prose nested in plan

The existing generation stack already has a metrical hierarchy; it lacks only the bottom rungs and the ear that reads them.

Plans and beats are the form of the piece — the structural plan a composer writes before the notes. Sonic analysis is the score as heard: what the realised notes do inside the form. The plan sets the goal of each beat (breathe, advance, turn, reveal, resolve, …); the sound is how the passage carries the listener to it.

3. The ontology — a western music vocabulary for prose, with candidate measures

Each element names a listening experience, the textual quantity that carries it, and a candidate measure. All measures are computed per beat (the section) and per scene (the piece); sentence-level values are the raw series. Notation: a scene has sentences (s_1..s_n); (L_i) = syllables in (s_i); (S_i) = stressed syllables in (s_i); (\sigma_i) = stress sequence of (s_i) as 0/1.

3.1 Metre — the pulse

Stress alternation is the beat the inner voice keeps. Measure the stress regularity: the lag-2 autocorrelation of the concatenated stress sequence (iambic/trochaic prose peaks at lag 2, dactylic at lag 3); report the dominant lag and its strength. Prose that never settles a pulse reads as prose; prose that locks one reads as verse. Both are choices — the measure names which, and where the pulse breaks.

3.2 Tempo and rhythm — the length series

(L_i) is the bar length. Tempo is mean syllables per sentence; rhythm is how (L_i) moves. The same turnover statistic the pacing classifier uses applies unchanged at this grain:

τ_sentence = mean|L_{i+1} − L_i| / σ(L)

τ near the memoryless point (≈1.13) is neutral; low τ is a held rhythm (runs of similar sentences); high τ is whiplash (long–short–long). A good passage usually shows local runs broken by a short bar at the moment of weight. Also report the short-bar rate: sentences under a third of the scene's mean length, and where they fall relative to beat boundaries.

3.3 Dynamics — loud and soft

Dynamics is felt intensity. Candidate loudness per sentence:

d_i = S_i / L_i  ·  (1 + punctuation weight)  ·  (mean L / L_i)^γ

— stress density, terminal punctuation (!, ?, — weigh more than .), and brevity (short sentences land louder), γ a dial. The dynamic curve (d_1..d_n) is decomposed with the same Legendre spectrum as the activity curve: a positive slope term is a crescendo, negative a diminuendo, curvature a swell or hollow, residual terraced dynamics. A beat with no dynamic range is a monotone; the founder's "crescendos and structures in music" are literally the first two Legendre terms of (d).

3.4 Contour — the melody line

Vowels carry pitch-like colour: front/high vowels (ee, i) read bright, back/low (oo, aw) dark. Map each stressed vowel to a two-dimensional (height, backness) position and read the contour: the sequence's drift across a sentence and across a beat. A sentence that descends into dark vowels at its close lands heavier than one that stays bright. Report drift and range per beat.

3.5 Timbre and dissonance — consonant colour

Consonant classes have sonority: liquids and nasals (l r m n) are smooth, fricatives (s f sh) hiss, plosives (p t k b d g) strike. Per beat report the class distribution and its clustering: runs of plosives within a clause read as hard; runs of liquids as fluid. Dissonance is the density of adjacent unlike-class clusters that are hard to voice (consonant pile-ups across word boundaries). Dissonance is not an error — it is tension, to be spent, not avoided.

3.6 Motif and repetition — what entrances

Music holds a listener by returning. Prose does the same with lexical motif (a word or phrase recurring), phonetic motif (alliteration, assonance, consonance — recurring onsets, recurring stressed vowels, recurring codas), and syntactic motif (parallel clause shapes). Measure recurrence by self-similarity of the beat's clause sequence on each channel; report motifs that recur ≥ 3 times, their spacing, and whether they cross beat boundaries (a motif that spans beats binds the scene; one confined to a beat colours it). Excess is doggerel; absence is prose that nothing holds together. The sweet band is a dial, calibrated on lyrics and on the operator's library.

3.7 Phrase and cadence — how things end

A phrase ends on a cadence; a sentence ends on its last stressed syllable and what follows it. Per sentence classify the ending: strong (final syllable stressed, monosyllabic close), feminine (trailing unstressed syllable), suspended (ends on a subordinate clause, a comma-spliced continuation, a question, a dash). Per beat and per scene report the cadence profile — the last sentence's ending class and its length relative to the beat's mean — and the resolution rate: what share of paragraphs end strong. A resolve beat that ends suspended, or a turn beat that ends on a feminine trailing clause, is a plan/sound mismatch the reading should surface.

3.8 Form — the beat sequence heard as structure

The BeatFn sequence is already a form (ABA, AABB, arch). Read it as music does: repetition (the same fn recurring), contrast (adjacent fns of opposite weight — breathe after turn), and return (the closing beat echoing the opening one). The existing BeatTransitionMatrix is the form's grammar; this spec adds the reading of a realised sequence against it and against the scene's dynamics — does the loud beat sit where the plan put the turn?

3.9 What is deliberately not in the ontology

Key, harmony, and chord progressions have no honest textual carrier; they are metaphor, not measure, and are excluded until someone shows a computable quantity. Semantic beauty (imagery, wit) is not sound and is out of scope here.

4. From reading to guidance — optimising prose

Macro analysis compares; sonic analysis prescribes. The loop the founder is asking for:

plan (BeatFn sequence, propositions, grain)
  → prose (per-beat passages, [BEAT:N] aligned)
  → sonic reading per beat: metre, tempo, dynamics, contour, timbre, motif, cadence
  → deviation from the beat's target profile
  → revision instruction for that beat only

A target profile is a small set of bands per BeatFn, e.g. breathe → low dynamics, long bars, smooth timbre, feminine cadence; turn → crescendo into a short strong bar; resolve → falling contour, strong final cadence, a returning motif. Targets are dials, authored once and calibrated against the library; they are prompt material (an extension of ProseProfile.sentenceRhythm, which today is a qualitative word), not stored state. The revision step edits one beat's passage and re-reads; the macro delta of the scene is unaffected because propositions are preserved — sound changes, structure does not. This is the sense in which the two grains are orthogonal and can be optimised independently.

5. Corpora and calibration

• Song lyrics are the calibration corpus for the sonic dials: high motif density, deliberate metre, cadences that must land. They tell us what "entrancing" measures as before we ask it of prose.
• Verse (metrical and free) brackets the metre dial: where regularity becomes verse.
• The operator's library — the records already extracted — is the prose baseline; the same records the macro grade reads give the sonic reading its reference bands, so a work can be read on both ears.
• Bands, not verdicts. As with the forces, a sonic reading is an instrument for a declared scene and target profile, never a cosmic judgment of beauty. Genre and voice legitimately live outside the bands.

6. Dependencies and honesty about English

Stress and phonemes require a pronunciation source. The candidate is the CMU Pronouncing Dictionary (ARPAbet with stress marks) with a rule-based syllabifier fallback for out-of-vocabulary words and names — and names are frequent in fiction, so the fallback's accuracy is load-bearing. This is English-only at first; other languages need their own lexicon and stress rules, and the ontology's vowel map is language-specific. No dependency exists in the repository today; none is to be added by this spec.

7. What is deliberately open

1. Sixth reading or finer grain? Whether sonic quantities are reported as a reading beside the five forces (a Score panel) or folded into each force's per-scene account is undecided. Nothing here makes them a force; they are not deltas and have no realisation ratio.
2. Per-beat force snapshots. Sonic reads per beat naturally; macro reads per scene. Whether the force snapshot should also be computed per beat (giving the activity curve intra-scene resolution) is a separate macro question this spec raises but does not decide.
3. Targets by fn alone, or by fn × mechanism? A dialogue turn and a narration turn plausibly want different sound.
4. Who hears? A reading assumes a reader's inner voice; dialect and reading speed change stress and tempo. The first cut assumes one standard voice and says so.

8. The honest ledger

9. Sources

• Founder notes, 2026-09-18 (macro/micro; sheet music as the parallel; lyrics as corpus; authors as textual musicians; scene ≈ 500 words as a composition; crescendos, structures, repeating patterns; music theory + syllables + prose + plans + beats as the foundation).
• Pentad spec — the macro measures this spec sits beneath.
• Positioning: delivery truth — grain paragraph; direction-not-capability rule.
• src/lib/core/forces/domain-utils.ts — Legendre spectrum and turnover τ, reused here at sentence grain.