The vocal tract behaves acoustically like a stopped tube of constant diameter

Evidence

The regular series of pulses from the vibrating vocal folds are modified by the acoustic properties of the vocal tract. In acoustic terms, the vocal tract can be considered as a stopped tube (closed at the larynx, which operates as a flow-controlled reed, and open at the lips) that is approximately 17.5 cm in length for an adult male. When the vowel at the end of announcer is produced, the vocal tract is set to what is referred to as a “neutral” position, in which the articulators are relaxed, and the soft palate (see Figure 4.34) is raised to cut off the nose; the vowel is termed “nonnasalized.” The neutral vocal tract approximates quite closely to a tube of constant diameter throughout its length, and therefore the equation governing modal frequencies in a cylindrical stopped pipe can be used to find the vocal tract standing wave mode frequencies for this vowel. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1344

Categorization

• DEFINE: Defines the neutral vowel and nonnasalized articulation via the stopped-tube model.
• XREF: Connects vocal tract acoustics to the woodwind reed stopped-pipe physics explored earlier in this book around Figure 4.23.