Quarter wave resonators
Quarter wave resonators are important in acoustics and can help us understand some of the characteristics of singing.
In vocal acoustics, the vocal tract acts as a resonant tube or quarter wave resonator that amplifies certain frequencies produced by the vocal folds. When air passes through the larynx and into the vocal tract, it encounters a series of resonances that enhance specific frequencies or harmonics.
A quarter wave resonator is a type of resonant cavity in which the length of the resonator is one-fourth the wavelength of the sound being produced. In the case of the vocal tract, it acts as a series of interconnected quarter wave resonators that enhance the harmonics produced by the vocal folds.
When a singer changes the shape of their vocal tract, they can change the resonant frequencies and therefore change the timbre or color of their voice. By altering the shape of the vocal tract, a singer can emphasize certain frequencies and de-emphasize others, resulting in different vowel sounds.
Additionally, the use of quarter wave resonators can also help explain the phenomenon of formants in singing. Formants are the resonant frequencies of the vocal tract that are amplified and determine the quality of the sound. The first two formants, also known as F1 and F2, are particularly important in vowel perception and are related to the size and shape of the oral cavity.
In summary, the use of quarter wave resonators is essential in understanding the mechanics of singing and how the shape of the vocal tract can affect the resonant frequencies and therefore the quality of the sound.