LBT095-097惠珍 Done on Jan 7’09
The order of corrected neuronal events may yet be different from the three orders discussed so far, although we are entering a realm in which we are almost entirely reduced t speculation. The reason for suspecting a neuronal firing order that is different from the order of motor events is the anatomy of the peripheral nerves that innervate the respective muscle. Figure 3.8 shows diagrammatically the course of some of the nerves that are relevant to this discussion. There is considerable differences in the length of these nerves; notice especially the circuitous course of the recurrent nerve which is more than three times conduction time of impulses does not merely depend upon the distance of peripheral nerve that must be traversed but also upon the diameter of the nerve fibers (the smaller the fiber. the slower the condition). It is possible to measure the average length of the peripheral nerves and also to make microscopic studies of cross sections of these nerves and to measure the size of the diameters of fibers. This has been done (Auriti,1954; Krmpotic, 1958 and 1959), and it has been found that nerves involved in speech muscle innervation vary considerably in their composition of a nerve in terms of a caliber spectrum (a statistical frequency distribution of diameter sizes). Table 3.4 shows a few figures taken from the work of Krmpotic, indicating that there is always some overlap in the distributions but that there are nevertheless, marked differences among the various nerves. It is interesting that the the longest nerve, the recurrent, has statically the smallest fibers which thus aggravates the timing problem, introducing delays from two independent factors.
相連的神經位元的排列可能還不會害目前所提到的三種排列方式不同，雖然我們一直想要減少推測的範圍。對於作用的神經細胞保持環一的態度，是因為他和其他運動的單位不同，這運動的單位是其他週邊單位的解剖學，會造成個別肌肉受神經的控制。3.8圖了顯示跟這研究討論有關的一些神經的方式的圖表。在這些細胞的長度有很大的不同；特別是有再生周期的細胞的習慣的繞行方式，會比其他受神經控制的下顎肌肉的細胞還要3倍。這樣的脈動運作方式並不只靠週邊必須掛越的神經的距離，還要看細胞的直徑(越小的細胞，越少的傳導運作方式)。要量週邊的細胞的平均長度是可能的，也可以用顯微鏡來做研究，來衡量細胞的直徑。(Auriti, 1954; Krmpotic, 1958 and 1959)則有做過這些，也發現了：在細胞的組成上，發音器官的肌肉受神經控制的狀況有很大的不同。對於神經的纖維組成的表現方式，用光普的方式來呈現，是很正常的( 一種統計學的方式)。3.4表則是從Krmpotic的數據而來，顯示出總是在分佈的地方有重複的地方，此外，在不同的細胞是有不同的。越長的細胞，他的反應週期，統計出來是越小的細胞作用的時間總計的問題，是受其他兩個獨立變數影響的狀況，是很有趣的。
Kirmpotic, who has been specially interested in the problem of differential innervation time, has computed so-called neuromuscular indexes for all major muscles involved in speech. These indexes are simply the ratio of the average length of the nerve to the mean size of fiber diameter. Since there is still some uncertainty about the physiological interpretation of these determinations, we need not be concerned here with the details. Suffice it ti say that the anatomy of the nerves suggests that innervation time for intrinsic laryngeal muscles may easily be up to 30 msec longer than innervation time for muscles in and around the oral cavity.
Kirmpotic ，對這種不同的反應時間的問題，感到特別有有趣，對於發音所用到到的肌肉，他寫了個神經肌肉的指示表。這個只是表只代表了平均的細胞直徑的神經長度的比例。因為還有很多對這重分類的生理學上的詮釋的狀況，還不是很確定，我們不需要對這細節太關心。如果說神經的解剖學能滿足的話，則表示類部聲帶的肌肉的受神經控制的時間，很經意的就達到30 msec， 比起裡面的肌肉和口腔器官的受神經支配的時間還長。
Considering now that some articulatory events may last as short a period as 20 msec, it becomes a reasonable assumption that the firing order in the brain stem may at times be different from the order of events occurring at the periphery.
A concrete example will clarify the point. Let us take the words obtain and optimal. If we make spectrograms of these words and measure and durations of the first three phones, we get values such as these:
Duration of Duration of
First vowel the labial stop the aspiration
Obtain 90 msec 170 msec 50 msec
Optimal 110 msec 160 msec 20 msec
有個比較具體的例子能解釋這。就拿obtain , optimal來說，如果我們用光譜來測量以及測量前三個音的發音時間，我們會得到以下的結果：
Among the acoustic cues for the discussion of certain voiced and unvoiced stops are the duration of the preceding vowel and the duration of the silence during which the lips are closed. Our perceptual acuity is highly sensitized to these temoral factores and , by the same token, our motor coordination is precise enough to times articulation with sufficient presision to bring about these distinctions. In the previous example the duration of the first vowel differs by only 20 msec and that of the labial stops by only 10 msec, and in the second instant, the duration of the aspiration (the only part of the /t/ we hear)lasts only 20 msec. Recent investigation carried out at the Haskins Laboratories have shown that a great variety of phonetic distinctions are entirely dependent upon timing factors of onset, duration, and cessation of voice where magnitudes well below 20 msec are od the essence. (See also the time relationships in the data reported on by Liberman, Delattre, Cooper, 1952; Schatz, 1954; and Liberman, Delatrre, Gerstman, and Cooper, 1956)
在區別某些有聲和無聲的塞音的一些語音上的技巧中，就是在嘴唇閉起來的，含前面的母音發音的長短，和有聲音的長短。我們敏銳的認知，是對這些有感覺的，也對提他相似的方式有感覺的。同樣的，我們的協和運動方式也對發音方式，有精確感覺，能夠區別不同之處。在前面的第一個母音的持續時間的例子中，不同的是只有20msec，唇塞音側只有10 msec，在第二的例子，是送氣的差別。(我們只聽到/t/)持續了20 msec 。最近的Haskins Laboratories的研究則指出：語音上的不同，是因為起始音、發音時間、聲音的中斷等因素影響，造成了強度低於20 msec。(參造Liberman, Delattre, Cooper, 1952; Schatz, 1954; and Liberman, Delatrre, Gerstman, and Cooper, 1956 的作品)
It is clear that there must be considerable precision in timing if laryngeal mechanisms are to integrated with oral ones. IN addition, there are hundreds of muscular adjustments to be made every second (that is a new neuromuscular event every few milliseconds) from which we begin to see the magnitude of the timing-ordering problem.
In view of the above we are hardly surprised that we may encounter patients with lesions in the central nervous system who have difficulty in keeping elements of speech and language in the right order. An important theoretical discussion on this subject was contributed by Jakobson and Halle(1956). Patients who have this problem speak very slowly and indicate to the examiner that speaking constitutes a great effort of concentration: the behave as if they had to “think of the right order.” Even so, they will constantly mix up individual sounds; is may become si, task may become taks, syllable may become syballel and they are very hard to understand.*Generally, they tend to anticipate sounds that should come at a later time. The difficulty may occur in every other word, since their rate of production is markedly slow down. The improper anticipation of sounds is usually nit the patient’s only problem of ordering. He will also show a pathological propensity for spoonerism, entire words and phrase s being switched around or produced in advance. The patient’s intention is frequently made known to the examiner because the patient is fully aware if his difficulty and can often make a fresh start and repeat the intended sentence once more and correctly . Ina sever cases the corrected sentence will show new mistakes.
從上面看來,我們很難不對會遇到的中有神經有機能損壞的病人很難不感到驚訝，這些病人都有說話的問題, 無法分清楚正確順序，也無法分別正確單位.。對這個問題, Jakobson and Halle(1956)的理論架構，是有幫助的。有語言障礙的病人,說話都很慢，也會對檢查員指出，講話時很難集中注意力：他們的表現就像是需思考「正確的順序」。此外，他們也常對語音的順序搞混；例如is 變成si, 變成taks, syllable 變成 syballel ，而且，他們都很難瞭解。* 病人都會絕得聲音應該晚一點出來。這狀況，在他們製造語言很慢時，是每一秒都會遇到，代表每一個字都有這樣的問題。精楚的對每個聲音都認知，並不是病人唯一的語言順序的問題。病人都呈有spoonerism(字音的無意互換現象)的病理傾向，通常都會把整個片語位置亂換，或是，提前說。對檢查員來說，他們都會預期這樣的狀況，因為病人本身都知道自己有語言的障礙，常常會重新開始，或是把句子在講一次，或是，再修改一次。在嚴重一點的病人，就算是重新修改的句子，也是錯的。