12 complete symptom paths42 guides and 60 questions in each1,460 Grade A articlesOne searchable, connected knowledge library140 official sourcesEvidence context with explicit limits
Hear the cycle

Sound Lab

Listen for the trigger, not only the noise.

Rhythm, system cycle and strongest location often distinguish movement, flow, vibration and electrical signals.

Describe your clue →
Drainage pressure01

Drain gurgling

Air bubbles through trap water during or after another discharge.

Trigger
fixture discharge
Strongest location
traps and branch drains
Open signal profile →
Sensory method

Describe first. Interpret second.

  1. TriggerWhat changed immediately before it began?
  2. CycleDoes it follow startup, flow, heating, wind or room use?
  3. LocationWhere is it strongest, and does that move?
  4. Stop conditionHeat, smoke, gas or electrical odor changes the response immediately.