They are acoustic marks that take place after gradual deflation of the cuff. Validated by intra-arterial
recordings, they were first suggested by Goodman and Howell in 1911. They include:
Phase 1: First appearance of low-frequency tapping
sounds
Phase 2: Softer and longer sounds
Phase 3: Crisper and louder sounds
Phase 4 (often absent): Initial muffling of sounds
Phase 5: Complete disappearance of sounds
recordings, they were first suggested by Goodman and Howell in 1911. They include:
Phase 1: First appearance of low-frequency tapping
sounds
Phase 2: Softer and longer sounds
Phase 3: Crisper and louder sounds
Phase 4 (often absent): Initial muffling of sounds
Phase 5: Complete disappearance of sounds