Pipe walls raise air impedance by reflecting pressure pulses back in phase

Evidence

This means that for bounded waves, the impedance depends on the surface area within the bounding structure and so will change as the area changes. As we shall see later, changes in impedance can cause reflections. This effect is important in the design and function of many musical instruments, as discussed in Chapter 4. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 174 (#expands, via linked claim)

Categorization

• XREF: connects to: Wall proximity alternately boosts or suppresses a source depending on phase.; Adjacent in-phase sources boost each piston’s efficiency N-fold through mutual pressure; Wall losses, not radiation, dominate resonance damping in narrow pipes (+4 more)

Related

• Bounded sound waves change impedance with tube area, causing reflections (similarity 0.89)
• An open pipe end only reflects sound when an impedance mismatch exists there (similarity 0.87)
• Narrower pipes raise acoustic impedance through in-phase wall reflections (similarity 0.87)
• Wall losses, not radiation, dominate resonance damping in narrow pipes (similarity 0.85)
• Open pipe ends invert pulse polarity while closed ends preserve it (similarity 0.83)
• A sound pulse passes an open pipe end unreflected when matching pressure exists outside (similarity 0.83)
• Any pipe diameter change causes partial sound reflection at the junction (similarity 0.83)
• Rigid-wall tube terminations fully reflect waves while open ends reflect with phase inversion. (similarity 0.82)
• Open pipe ends invert compression pulses while closed ends preserve them (similarity 0.81)
• A rigid wall raises the impedance of adjacent air cells (similarity 0.80)
• An open pipe end inverts a sound pulse’s sign via a reflected rarefaction (similarity 0.80)
• Open and closed pipe ends reflect pressure pulses with inverted phase (similarity 0.80)
• Waves split into reflected and refracted parts at impedance-mismatched interfaces (similarity 0.80)
• Wall proximity alternately boosts or suppresses a source depending on phase. (similarity 0.80)
• Pipe diameter changes reflect pressure pulses with opposite sign (similarity 0.80)

Broader Connections

• Bounded sound waves change impedance with tube area, causing reflections #expands (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 174
• Open pipe ends invert pulse polarity while closed ends preserve it #expands (0.80)
• An open pipe end only reflects sound when an impedance mismatch exists there #qualifies (0.75)