Phonation types differ by glottal airflow and spectrum shape

Evidence

During speech production, humans are able to control the vibration mode of the vocal folds, hence varying the characteristics of the airflow pulses that are generated at the glottis as an acoustic excitation of voiced speech. Phonation types can be divided into three different categories: breathy, modal (or normal), and pressed (Alku and Vilkman, 1996). In breathy phonation, the area of the glottis is a smooth, almost sinusoidal function of time. The corresponding airflow pulse is also smooth in time, with a low-frequency emphasis in its spectrum. Breathy phonation typically has a non-zero leakage of air through the vocal folds over the entire glottal period. In modal phonation, the glottal area and the corresponding flow pulse are more asymmetric between the opening and closing of the glottis (see Figure 5.3 for an example of glottal flow during phonation). In pressed phonation, the closing phase shortens further in time, hence producing an excitation pulse that has more high frequencies in its spectrum. In addition to these three basic phonation types, humans are also capable of adjusting their glottal function to produce, for example, a creaky voice and whispering. In the former, the vibration mode of the vocal folds is irregular, involving two different modes that alternate in time, a phenomenon called diplophonia, and the duration of the closed phase is typically relatively long. Whispering is a speech production mode in which the vocal folds do not vibrate at all, and the sound excitation is produced by an exhaled airflow from the lungs. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 552

Categorization

• DEFINE: The full taxonomy of phonation modes (breathy/modal/pressed plus creaky and whispering) with spectral consequences is clearly and compactly defined here.
• XREF: Connects to the reader’s ongoing interests in the mechanics of voice production and to source-filter theory used elsewhere in acoustics.
• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 552