Lofn Render Audit — what the generator actually did

Every gate in this pipeline reads text. Until 2026-07-24 nothing had ever measured a finished render, so a whole class of failure was invisible by construction: a song can pass all 16 points of the Suno gate and arrive with its defining gesture gone.

This skill is judge-side. Golden song payloads are permitted here. It generates nothing.

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⚖️ THE GRAIN LAW — the finding this skill exists to apply

The founding comparison — the first three tracks measured, 2026-07-24 (two new, one Staff Pick). It is kept because it is the case that produced the law; the current evidence base is the n=8 ledger below, which supersedes any number here.

specified	It Wasn't Even Locked	Start With One	Triple Arch Over Me
L-R correlation	0.945 (mono)	0.908 (mono)	0.812 (real stereo)
near-silent opening	—	—	survived, −41 dB
"more sub at the end"	—	—	survived, +8.4 → +11.4 dB
~4 s full stop	0.40 s / 5.7 dB	—	—
quarter-tone drone pair	zero tonal components	—	—

The rule is not "production never survives." My first draft of this finding said that, from a sample of two, and the benchmark disproved it.

Specs that run WITH the generator's grain survive. Specs that run AGAINST it get smoothed.

With the grain — things a pop arrangement wants to do anyway: open quiet, build sub, thicken toward the last chorus, widen a pad, add air. These render, often beautifully. Against the grain — anti-musical instructions: stop the take dead for four seconds, hold two untuned drones a quarter-tone apart, hard-pan a mains hum, refuse to correct a limp. These get smoothed, because smoothing is what the model does.

Consequences that bind the writing tiers:

1. A Somatic-Gate or distinctiveness objection answered in the production spec is not answered. It must be answered in the lyric or the form, which survive. (On 2026-07-24 a REPAIR — 2/3 was closed with a mix decision that never reached audio.)
2. A hollow centre whose mechanism is "the mix collapses to mono" is unfalsifiable when the render is already mono. Pick a mechanism the render can carry — or accept that it lives on the page.
3. Spatial language is cheap to write and usually free of consequence. Do not spend the character budget on it or let a song depend on it.

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🎨 THE SCIENTIST'S LAW — judge the result, not the distance from intent

Stated 2026-07-24 and load-bearing for this whole skill:

"The generators are imperfect and rarely do your actual prompts justice. I judge the final result, not the distance from intent. As long as the message survives and the song sounds amazing, it is worth publishing. For art, just having a moving piece, even if unintended, is a worthy discovery. Finding out and using the generator's flaws as techniques — having it fail in just the right way — can create new sonic experiences."

This skill must never be used to compute a compliance score. An intent-vs-render diff is raw material, not a grade. Three standing rules:

• A deviation is a finding, not a fault. Report it neutrally; let the human's ear rule.
• Hunt for the productive failure. On the benchmark, width correlates −0.43 with level: it narrows as it gets loud, the exact inverse of the specified "chorus widens like a panorama." For a song whose thesis is "I am not the center, I am included," narrowing into the climax is arguably truer than widening. That inversion is a technique now. Log deviations that improved the piece into vault/COMPETITION_LEARNINGS.md as reusable moves.
• A song that lost every production gesture and still moves the listener is evidence about where the load belongs — the writing — not evidence of failure.

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RUN IT

Pass 1 — numeric (always; no network, no key)

pip install numpy soundfile          # libsndfile >= 1.1 decodes MP3
python3 scripts/measure_render.py <track.mp3> [...]      # JSON to stdout

Reports: duration · peak/crest · loudness spread · opening level · sustained quiet gaps · deepest mid-third dip (depth AND width) · tempo candidates · per-quarter band energy · stereo correlation & side/mid · width-vs-level correlation · isolated sustained tones · interval pairs.

⚠️ Trust its guards, and keep them. An earlier version reported six quarter-tone drone pairs that were adjacent FFT bins in one low-frequency cluster — at 60 Hz the neighbouring bin is ~3 % away, so the result was arithmetic. The prominence floor and the 50-cent separation exist because of that. A validator confident enough to fail an artifact deserves at least as much suspicion as the artifact.

Pass 2 — listening model (when a key and egress exist)

Backend: GPT-5.6 (audio-capable) via the Poe OpenAI-compatible endpoint https://api.poe.com/v1 with POE_API_KEY (see TOOLS.md), or any audio-capable endpoint available in the environment. Neither key nor egress is available in the sandboxed web session — run this pass locally, or pass the audio through whatever channel the session does have.

🔒 THE BLIND RULE — the whole validity of this pass depends on it. Send the audio ALONE first. Do not send the prompt, the title, the lyrics, the intent, or this skill's expectations. A model shown the intent will confirm the intent. This is the same clean-context discipline QA runs under, for the same reason.

Prompt for the blind pass:

Listen to this track and describe only what you actually hear. Do not guess at intent.

1. Structure with timestamps — where sections begin and end.
2. Any silence or near-silence longer than one second — where, and how long.
3. Sustained non-musical sound (hum, drone, whine, motor, machine noise) — where, and roughly what pitch.
4. Stereo image — what sits left, right, centre; does the width change, and where?
5. The vocal — register, distance from the mic, dry or reverberant, doubled or single.
6. The single most distinctive sonic event in the track, and its timestamp.
7. Anything that sounds like an artifact, a glitch, or a mistake — and whether it works.
8. In one sentence: what is this song about, from the audio alone?

Then, and only then, a second turn with the style prompt, exclude prompt and lyrics attached:

Here is what was asked for. For each specified element, say: ARRIVED / PARTIAL / ABSENT / INVERTED, with the timestamp that justifies it. Flag anything the render does that was not asked for and is better than what was.

Cross-check the listener against Pass 1. Item 2 must agree with quiet_gaps and deepest_mid_dip; item 3 with sustained_tones_hz; item 4 with stereo and width_dynamics. Where they disagree, the numbers win on presence/absence and the listener wins on quality and meaning. A listener claiming a four-second silence the envelope does not show is confabulating; an envelope showing a dip the listener never noticed is a dip that does not matter.

Pass 3 — write it down

• Per-track audit → output/<run>/RENDER_AUDIT.md: the intent table (ARRIVED/PARTIAL/ABSENT/INVERTED), the numbers, the listener's blind read, and the productive deviations.
• Any deviation worth reusing → vault/COMPETITION_LEARNINGS.md as a named technique.
• Any generator behaviour that recurs → the Suno behaviour ledger below.
• Operational failures → vault/RUN_LEDGER.md.

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📓 THE SUNO BEHAVIOUR LEDGER — n=8, first full deep dive (2026-07-24)

Eight finished renders, numeric + blind listen. This table replaces the n=1/n=2 guesses that preceded it; two of those were wrong.

spec class	behaviour	n	confidence
steady tempo target	ARRIVES — 6 of 6 landed within 5 BPM (110→109, 132→133)	6	medium-high
tempo dramaturgy (programmed 92→140, 84→128)	SMOOTHED to a steady track	3	medium
near-silent opening	arrives (−46.8 dB when asked; also appears unrequested)	3	medium
terminal silence (ends the arrangement)	ARRIVES — 2.0 s measured	1	low-medium
interrupting silence (long mid-song void)	SMOOTHED — every explicit void vanished; the third is a THIRD-PARTY render (2026-08-22), so it is the generator, not our prompting	3	medium
progressive sub build to final chorus	arrives (+8.4 → +11.4 dB)	1	low-medium
literal foley props (boot crunch, chair drag, scanner beep, printer chirp)	ABSENT or abstracted to generic glitch	≥4	medium
two strongly opposed vocal registers	collapses to one lead + ordinary layering	2	medium
named exotic timbres (HyperRaaga, tanpura, glass harmonica, cello, crystalline arps)	largely absent; atmosphere substituted	≥3	medium
sustained untuned drone / mains hum	absent	2	low-medium
hard-panned non-musical element	absent	2	low-medium
stereo image	spans 0.812–0.945 correlation — NOT a universal mono renderer	8	medium-high
"chorus widens"	≤ 0 on every track ever measured — r = −0.426 / −0.067 / −0.544 / −0.348. Zero positive in 4. Candidate reclassification: not a deviation but a property of the generator, which would put "the chorus widens like a panorama" on the wrong side of THE GRAIN LAW	4	low-medium

Corrections this set forced on my earlier claims:

• "Exact BPM drifts" was wrong — an artifact of a 50 ms analysis hop (a beat at 110 BPM is 11 frames). Steady tempos arrive; only tempo dramaturgy is smoothed. measure_render.py now runs tempo on a 10 ms hop.
• "Suno renders mono" was wrong — two samples that both fought the grain.
• Silence is not one behaviour. Silence that finishes an arrangement survives; silence that interrupts one gets filled. That distinction is the single most useful row here.

Method: keep n visible; nothing rises above medium under 4 tracks. Two rules already died of a sample of one or two.

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⛔ THE LISTENER CONFABULATES — AND IT CONFABULATES TOWARD THE DEFAULT

Added 2026-08-22, measured on three tracks with two models (gpt-audio-1.5, qwen3.5-omni-plus).

Pass 2 is not a witness of equal standing to Pass 1. On three tracks the listening model was wrong in the same three ways every time, and each error was the conventional pop answer:

listener claim	how often claimed	truth from Pass 1
"it fades out"	4 of 4 track-model pairs	all three tracks end at −13 to −18 dB in the final seconds. No fade anywhere.
"the stereo widens on the loud parts"	3 of 3 tracks	width-vs-level r = −0.067 / −0.544 / −0.348. Zero or negative on all three.
"near-silence at the opening"	1	opening_2s_db = −16.8 dB.

Where it is strong: "what is this about" (two models, blind, independently returned the event of a song neither had a title for), "the single most distinctive event" (found a real written structural device inside a third-party remix), and the presence of a continuous drone (3/3).

⭐ The operating rule, sharpened: the skill already said numbers win on presence/absence, the listener wins on quality and meaning. Now the failure classes have names. Envelope, endings and stereo width are where it invents — never accept any of the three from a listener without the meter beside it. And a listener that agrees with your intent about the envelope is agreeing with the pop default, not with your render.

⭐ Corollary worth keeping: on ASK FOR IT BY NAME a 45 dB, 30-second sub-bass withdrawal and return — the largest arrangement event in the track — was reported by neither model, one of them explicitly denying it when asked point blank. The spec had asked for a sub "felt through the boards before it is heard." An event that is physical rather than melodic is invisible to an ear-only pass, which is the whole argument for running both.

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🔧 PRODUCTIVE DEVIATIONS — the flaws worth reusing

The Scientist's award-winning thought, made concrete. These are techniques now, harvested from failures.

• UNBROKEN BUREAUCRACY — a requested rupture disappears, and continuous playback becomes a system that never pauses for the damage it caused. (It Wasn't Even Locked: the four-second stop vanished; the dead-level continuity is more relentless than the break would have been.)
• INWARD COSMOS — the mix narrows as level rises instead of widening, drawing the scale in around the singer. Truer to inclusion than spectacle. (Triple Arch Over Me, r = −0.426.)
• THE WOUND INSIDE THE MACHINE — a human voice left audible under a vocoder that was supposed to erase it; less clinical, more legible. (Harder to Reach.)
• GRIEF THE CLERK WITHHELD — harmonies supply the feeling a flat bureaucratic delivery was instructed to refuse. (The Cell Named After No One.)
• THE HAUNTED CHORUS — unrequested vocal layers turn a private metamorphosis into a small crowd. (The Caterpillar.)
• SINGULARITY BY GLITCH — an ordinary pop stutter becomes the one production event that physically enacts the word "one". (Start With One.)

How to use these: they are not instructions to Suno — asking for them would put them back on the wrong side of the grain. They are things to recognise and keep when a render hands them to you, and reasons to listen before repairing.

WHEN NOT TO USE THIS

• Text-only QA → lofn-qa.
• Generating or repairing lyrics/prompts → lofn-music.
• Never to compute a compliance percentage, and never to overrule a human ear that likes the track.

The render is the work. The prompt was only ever the request. 💜