Doppler Effect Calculator (sound) mechanism

Model scope

The core classical still-air Doppler formula is standard, but the specification needs explicit sign mappings, a defined shift-percent formula, unit validation, and domain constraints. The honest label is appropriate only when motion is relative to a stationary medium and relativistic, wind, and multidimensional effects are excluded.

• The ±/∓ signs are not explicitly mapped to approaching versus receding motion; a standard convention is approaching: f_obs=f_src(v+v_obs)/(v-v_src), receding: f_obs=f_src(v-v_obs)/(v+v_src), with velocities measured along the source-observer line relative to the still medium.
• The output shift percentage is specified but its formula is missing; it should be shift_percent=100*(f_obs-f_src)/f_src, assuming f_src is nonzero.
• The formula assumes collinear source and observer velocities and a stationary, homogeneous medium; these constraints are not stated in the input specification.

Units and conventions

• All velocities must use the same unit before substitution; the examples use m/s unless explicitly converted.
• The speed of sound is 343 m/s for still air at 20 °C.
• Source and observer velocities are measured relative to the medium and along the line joining source and observer.
• Shift percentage is signed relative to the emitted frequency: positive means an increase and negative means a decrease.
• The source frequency must be greater than zero.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "source_frequency_hz": 440,
    "speed_of_sound_m_s": 343,
    "source_velocity_m_s": 0,
    "observer_velocity_m_s": 0,
    "motion": "stationary"
  },
  "expected_outputs": {
    "observed_frequency_hz": 440,
    "shift_percent": 0
  },
  "working": "Stationary case: f_obs=440*(343+0)/(343-0)=440*343/343=440 Hz. shift%=100*(440-440)/440=0%."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The calculator breaks or must reject an exactly sonic approaching source because the Doppler denominator becomes zero. It is also vulnerable to materially incorrect results if the approaching/receding branch or velocity sign convention is inferred ambiguously.

Other records

Sources and evidence

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

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json