Acoust. Sci. & Tech. 37, 4 (2016) #2016 The Acoustical Society of Japan

Virtual model for education in phonetics tory movements’’ and ‘‘Respiratory movements while phonat- and science ing.’’ The animations were created by Shade 3D (Ver. 12) on a Mac. Takayuki Arai1;Ã and Takashi Arai2 2.1. Normal respiratory movements 1 Sophia University This section explains the normal movements of our 2 Fukujuji Hospital, Japan Anti-Tuberculosis Association . First, the animations tell us about the (Received 28 September 2015, Accepted for publication 18 difference between quiet and deep/forced breath- November 2015) ing. In particular, it is explained how the external intercostal muscles and the diaphragm work during quiet breathing. Keywords: Lung model, , Animation, Education These muscles are contracted during , but none PACS number: 43.10.Sv [doi:10.1250/ast.37.173] of the muscles are contracted during exhalation. However, during deep/forced breathing, the external intercostal muscles 1. Introduction and the diaphragm work as hard as possible, while a number We have already demonstrated that human lung models of other muscles called accessory respiratory muscles assist. are useful when providing education on total speech produc- Finally, the difference between thoracic breathing and tion systems in phonetics and speech science [1,2]. In our abdominal breathing is explained. previous studies, we applied balloons for the lung model. The two main balloons are placed in a sealed but transparent 2.2. Respiratory movements while phonating cavity that acts as a . The two balloons are In this section, respiratory movements during vocalization connected with a Y-shaped tube whose main pipe is placed in are clarified. The main force during the exhalation is supplied the neck part of the sealed cavity. The main pipe protrudes by the contraction of the abdominal muscles (see Fig. 2). It is from the sealed cavity in the neck and is connected to an explained why abdominal breathing is recommended for artificial . This enables us to simulate one trachea singing. having two bronchi, each of which leads to one of the balloons (). Because this model has a membrane at the lower side 3. Discussion and conclusion of the thoracic cavity, it acts as a diaphragm. When we pull The series of animations of the lungs proposed here has the diaphragm down, the relative air pressure inside the great potential for educational application in several fields. thoracic cavity becomes negative and the two balloons inflate Our original target was students studying speech science, because the air inside them is essentially movable to outside human , and related areas including the cavity via the larynx. This explains how inhalation works. phonetics. It is often difficult for students to understand the In contrast, when we push the diaphragm up, the relative air mechanisms behind the human and how the muscles pressure inside the thoracic cavity becomes positive and the work, and reading textbooks or looking at 2D illustrations two balloons deflate. This explains how exhalation works. does not provide much help. In contrast, 3D animations with During the exhalation phase, the air inside the balloons exits computer graphics are tremendously helpful when it comes to through the larynx and the artificial larynx produces a glottal with the appropriate transglottal pressure. This physical lung simulation can be extended to the demonstration of vowel production [1,2]. When we attach a vocal-tract model on top of the artificial larynx, a corresponding vowel can be produced during exhalation (see Fig. 1). With this type of demonstration, we can show a total system of speech production including breathing, phonation, and articulation. However, this demonstration does not provide any details of the muscular activity or how the volume of the thoracic cavity changes. To provide these details, we created a series of animations using 3D computer graphics. These animations are a part of our ‘‘Acoustic-Phonetics Demonstrations’’ project, or APD. For a description of the entire project, please see [3] or visit our Web site (www.splab.net/APD/).

2. Animations of the lungs The series of animations of the lungs based on the human anatomy [4] consists of two main sections: ‘‘Normal respira-

Ãe-mail: [email protected] Fig. 1 Lung and head-shaped models.

173 Acoust. Sci. & Tech. 37, 4 (2016)

Fig. 2 Muscles working during vocalization: (a) inhalation and (b) exhalation.

assisting students in visually and intuitively imagining how Acknowledgments these mechanisms work. This type of educational aid can be This work was partially supported by JSPS KAKENHI used not only by instructors in classrooms but also by the Grant Number 15K00930. students themselves. The animations can also be used in clinical situations—i.e., by medical doctors and pathologists References and/or by patients themselves. Furthermore, the applications [1] T. Arai, ‘‘Lung model and head-shaped model with visible vocal can be extended to other fields, such as musicology. tract as educational tools in ,’’ Acoust. Sci. & Tech., 27, Professional vocalists as well as people who simply enjoy 111–113 (2006). singing should also appreciate the animations because, since [2] T. Arai, ‘‘Education system in acoustics of speech production muscle control for singing is crucial, being able to understand using physical models of the human vocal tract,’’ Acoust. Sci. & Tech., 28, 190–201 (2007). how it works would be of great benefit. In the future, we [3] T. Arai, ‘‘Learning acoustic phonetics by listening, seeing, and would like to combine physical and virtual models to create touching,’’ Proc. Meet. Acoust., 19(025017), 1–9 (2013). more sophisticated systems for education in acoustics, speech [4] S. Standring, Gray’s Anatomy, 40th ed. (Churchill Livingstone, science, phonetics, and so forth. London, 2009).

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