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

instrument implementation / implementation-contract

# Loudness Unit (LUFS) Reference / Target Checker implementation

A source-bound implementation contract for Loudness Unit (LUFS) Reference / Target Checker; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t7-083

**Effect**: Computation or source lookup only

## Input and validation requirements

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.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "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."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/loudness-unit-lufs-reference-target-checker/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/loudness-unit-lufs-reference-target-checker/mechanism/>)[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`