Acoustic waves reflect at discontinuities in tract area

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)

Standing waves occur when sound waves bounce between reflecting surfaces. The simplest system in which this can occur consists of two reflecting boundaries, as shown in Figure 1.30. In this system, the sound wave shuttles backward and forward between the two reflecting surfaces. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 386 (#expands, via linked claim)

Categorization

• XREF: connects to: The speech tract is modeled as a transmission line with pressure and volume-velocity variables; Vocal tract sound transmission is governed by cross-sectional area; Bounded sound waves change impedance with tube area, causing reflections — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 174 (+2 more)

Broader Connections

• Bounded sound waves change impedance with tube area, causing reflections #expands (0.95) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 174
• Sound waves reflecting between two boundaries can form standing waves #expands (0.82) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 386
• Speech excitation is not coupled to tract resonances, unlike most instruments #complicates (0.72)