Source: https://guthlabs.ai/docs/instruments/loudness-unit-lufs-reference-target-checker/mechanism/

instrument mechanism / verified-clean

# Loudness Unit (LUFS) Reference / Target Checker mechanism

The inspectable method record for Loudness Unit (LUFS) Reference / Target Checker, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The comparison concept is valid, but the instrument needs a documented gain-adjustment sign convention, an explicit pass tolerance, versioned provenance and effective dates for each target, and clearer labeling that these are nominal guidance/reference values rather than universal platform guarantees. Actual LUFS analysis remains out of scope as stated.

- The gain-adjustment sign is ambiguous: if delta = measuredLUFS - targetLUFS, the gain needed to reach the target is targetLUFS - measuredLUFS, which is the negative of delta.

- The specification does not define a pass/fail tolerance. The vectors below assume pass only when measuredLUFS exactly equals the nominal target.

- The listed Spotify and YouTube values are commonly cited guidance values, not necessarily immutable platform requirements; platform normalization policies and targets may change.

- EBU R128 at -23 LUFS is a broadcast loudness target/nominal reference, not a platform-delivery target.

## Units and conventions

- LUFS means integrated loudness in LUFS/LKFS-equivalent units; LUFS values are treated numerically as dB-like quantities for differences.

- The gain adjustment is defined here as targetLUFS - measuredLUFS, in dB: a negative value means attenuate and a positive value means increase gain.

- Pass means exact equality to the nominal target because no tolerance was supplied.

- The supplied measured value is already an integrated loudness measurement; this checker performs no audio analysis or LUFS conversion.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "measured_integrated_lufs": -12,
    "target_platform_preset": "Spotify"
  },
  "expected_outputs": {
    "target_lufs": -14,
    "delta_measured_minus_target_lufs": 2,
    "gain_adjustment_suggestion_db": -2,
    "pass": false
  },
  "reference_data": {
    "Spotify_target_lufs": -14,
    "source_convention": "widely tabulated platform guidance value; verify current Spotify documentation"
  },
  "working": "1. Target = -14.0 LUFS from the Spotify table row. 2. Delta = measured - target = (-12.0) - (-14.0) = 2.0 LUFS. 3. Gain adjustment to reach target = target - measured = (-14.0) - (-12.0) = -2.0 dB, so reduce gain by 2.0 dB. 4. Pass test: -12.0 == -14.0 is false."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The specification has no division or domain trap, but an extreme finite LUFS input causes the target offset to disappear through floating-point precision, and the instrument does not state finite-range or plausibility validation. The sign of the reported gain adjustment is also convention-dependent unless delta and corrective gain are kept distinct.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/loudness-unit-lufs-reference-target-checker/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/loudness-unit-lufs-reference-target-checker/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/loudness-unit-lufs-reference-target-checker/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche7/tranche7-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`