LB085-089T

LB85-89
(3) Other Motor Changes Indirectly Related to Respiratory Adaptations
The principal adaptations are summarized in Table 3.3 In Chapter two we have pointed out that the geometry of the naso-velo-pharyngeal space has a unique configuration in man and that this deviation from the rest of the primate order may be related to man’s unique posture. A consequence of the morphological peculiarity is that parting of the lips lets air stream simultaneously through oral and nasal cavities. However, during speech air is intermittently shunted either through the mouth, the nose, or both simultaneously, and muscular mechanisms exist to effect these movements quickly and efficiently. The nature of these movements is shown in Figs. 3.4 and 3.5. They have been thoroughly investigated by Björk (1961). Figure 3.5 is a demonstration of the relative speed, accuracy, and timing which integrates palatal movements into the speech event as a whole. Whether there are homologous mechanisms in lower primates is not clear (Müller, 1955). At any rate, the physiology of their movements in deglutition and phonation has apparently not been investigated.
主要的調適摘要於表3.3。在第二章，我們已指出鼻-顎-咽空間在人類有獨特的配置，而此項偏離其它靈長目動物的現象或許和人類獨特的姿勢有關。這項形態學上的特點有一個後果，那就是嘴脣張開會讓氣流同時通過口腔和鼻腔。然而，在說話時，空氣間歇地轉軌，通過嘴，鼻，或同時通過兩者，而存在著一些肌肉的機制來迅速且有效率地實現這些動作。這些動作的本質呈現在圖3.4和3.5。Björk (1961)已徹底地研究了這些動作。圖3.5展示了將顎部動作整合入整體說話事件的相對速度、準確度以及時機。在較低等的靈長類身上是否有同源的機制並不明確(Müller, 1955)。無論如何，有關牠們的吞嚥和發聲動作的生理學顯然尚未被研究。
When the vocal folds are spread apart during quiet breathing, the larynx constitutes a tubular air tunnel with somewhat irregularly shaped walls. The shape of the walls is altered during phonation and, as Fink and Kirschner (1959) have noted, some regularities are introduced in the subglottal space that favor the aerodynamics of sound production by reducing subglottal turbulence and thus increasing the efficiency in utilization of air flow. When the cords are brought together for phonation, their medial edge becomes sharpened, their superior surface flattens and forms a shelf, whereas the inferior surface is arched exponentially as shown in Fig. 15 of Chapter 2. Pressman and Kelemen (1955) state that “the advantage of such a curve inferiorly is twofold: (1) it thins out the medial mass of the cord without narrowing it or depriving it of a wide lateral attachment, thereby improving its vibratory characteristics; (2) because it is dome-shaped, the pressure of air converges from below to a point in the midline where the cords are thinnest. Under these circumstances, the free margins of the cords can, during phonation, be more easily blown apart by the pressure of expired air.”*
當聲帶在安靜呼吸時分開，喉頭構成一個管狀的風洞，其管壁有些不規則。管壁的形狀在發聲過程中會改變，而且如同Fink and Kirschner (1959)已指出的，聲門下空間開始變得規則一些，這利於產生聲音的空氣動力，原因是聲門下擾流減少，增進氣流運用的效率。當聲帶為了發聲而併攏時，中段的邊緣變得輪廓分明，其上部的表面變平且形成擱板狀，而其下部的表面，如第二章圖15所示，陡然地拱起。Pressman and Kelemen (1955)認為，”往下彎曲有兩方面的優勢：(1 )這使得聲帶的中部變薄，但不會使得聲帶整體變窄或使其無法往側向附著，於是增進了聲帶的振動特質；(2)因為聲帶為圓頂形，空氣的壓力從下匯流到其中線，而此處是聲帶最薄的地方。在這些情形下，聲帶閒置的邊緣在發聲過程中就能夠更輕易的被呼出空氣的壓力所吹開。

Kainz (vol. III, 1954) who summarized all respiratory and motor changes accompanying speech, also cites a difference between the position of the vocal folds during inhalation while the individual is quiet and during phonation. In the former, the muscles are relatively relaxed, forming a roughly triangular opening in cross section; whereas during speech, further retraction of the cords takes place to increase the available space, thereby facilitating rapid inspiration. During exhalation the cords are thought to assume a similar position as during inhalation as long as breathing is quiet and under relaxed conditions (which is not the case during laryngoscopy), whereas they are subjected to a rapid succession of adduction (during phonation), abduction (during unvoiced sounds), and tight adduction (during the production of glottal stops—which are lacking in some languages).
Kainz (vol. III, 1954)簡述了所有伴隨言語而來的呼吸和運動的變化，他也引述了一項在吸氣過程中，聲帶位置在個體安靜與發聲這兩個情況下的差異。在第一個情況下，肌肉相對地放鬆，在剖面上形成了一個像三角形的開口，而在說話時，肌肉進一步地收縮以增加可用的空間，於是促進了快速的吸氣。在呼氣的過程中，只要呼吸是無聲而在放鬆的條件下，聲帶被認為呈現一種與吸氣時相似的位置(但喉鏡檢查的結果並非如此)，然而，這些肌肉承受了一連串快速的內縮(在發聲過程中)，外展(發無聲子音時)，以及緊內縮(發喉塞音時，有一些語言缺少這類聲音)。

Throughout phonation, the cords are brought together but not so tightly as to prevent them from vibrating when air is blown through them from below. The individual vibrations themselves are not the result of neurogenic muscular twitches as proposed by Hussonand his followers, but, as is generally agreed now, depend on simple maintenance of muscle tonus, tissue elasticity of the vocal folds, and air pressure.
在發聲過程中，聲帶會靠攏，但是在氣流由下往上流過聲帶時，卻不至於緊到振動不了。個別的振動本身並非如Hussonand與其信徒所言，係神經性的肌肉抽動，而是如現在一般被接受的是取決於單純的肌肉強直性的維持，聲帶的組織彈性和氣壓。