Microphone Polar Pattern / Proximity Effect Reference

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Audio, Music, Photography & Color

Tranche

tranche-6

Evidence ID

t6-063

Ledger rows

1

No ledger note is attached.

Review findings

The three polar formulas are standard idealized textbook patterns, consistent with the existing honest-label warning. Verdict is NEEDS_REVIEW because the angle unit and figure-8 signed-versus-magnitude semantics are unspecified, and the proximity-effect portion is not mathematically defined.

Formula and scope findings

• The cardioid formula 0.5 + 0.5 cos(theta) is the standard idealized normalized cardioid response.
• The omni formula 1 is correct for an idealized normalized omnidirectional pattern.
• The figure-8 formula cos(theta) is correct as a signed transfer response, where the rear lobe has opposite polarity. If 'relative sensitivity' means nonnegative pickup magnitude, the displayed quantity should instead be abs(cos(theta)); this signed-versus-magnitude choice is unspecified.
• The proximity-effect claim has no formula, distance model, frequency assumption, or quantitative output, so it cannot be verified or deterministically plotted from this specification.

Unit assumptions

• Angles must be explicitly defined; the vectors below use degrees converted to radians before evaluating JavaScript cosine functions.
• Sensitivity is dimensionless and normalized to 1.0 on-axis.
• Angles are interpreted modulo 360 degrees.
• For figure-8, expected values use signed sensitivity. A magnitude-only display would use the absolute value instead.
• The proximity-effect note is qualitative only; no distance units or bass-boost units are specified.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

A very large JSON angle such as 1e309 becomes Infinity in JavaScript, causing Math.cos(Infinity) to return NaN for cardioid and figure-8. The instrument should reject non-finite angles but may instead render undefined or corrupted plot data. The unspecified angle unit also permits materially different sensitivity values.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "pattern": "cardioid",
    "angle_deg": [
      0,
      90,
      180
    ]
  },
  "expected_outputs": {
    "sampled_points": [
      {
        "angle_deg": 0,
        "relative_sensitivity": 1
      },
      {
        "angle_deg": 90,
        "relative_sensitivity": 0.5
      },
      {
        "angle_deg": 180,
        "relative_sensitivity": 0
      }
    ],
    "key_curve_features": {
      "maximum": {
        "angle_deg": 0,
        "value": 1
      },
      "rear_null": {
        "angle_deg": 180,
        "value": 0
      },
      "range": [
        0,
        1
      ]
    }
  },
  "working": "theta=0 degrees=0 radians: cos(0)=1; sensitivity=0.5+0.5*1=1.000000. theta=90 degrees=pi/2 radians: cos(pi/2)=0; sensitivity=0.5+0.5*0=0.500000. theta=180 degrees=pi radians: cos(pi)=-1; sensitivity=0.5+0.5*(-1)=0.000000. The cardioid maximum is at 0 degrees and the rear null is at 180 degrees."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

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

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche6/tranche6-results.json
• BOUNDARY_HAZARD_CATALOG.json