Volume 22, Issue 6, November 1950
Index of content:
22(1950); http://dx.doi.org/10.1121/1.1906671View Description Hide Description
22(1950); http://dx.doi.org/10.1121/1.1906673View Description Hide Description
Phonemics having been atomistic, it is now completed by typology, or integral phonemics. Encoding,entropy, spelling reform. Criteria for classifying given vocabulary. Monosyllabics‐parallelogram. Phonetic nets. Frequency distribution of vowels in monosyllabic words (French, English, German).
22(1950); http://dx.doi.org/10.1121/1.1906674View Description Hide Description
Physicists describe speech with continuous mathematics, such as Fourier analysis or the autocorrelation function. Linguists describe language instead, using a discontinuous or discrete mathematics called “linguistics.” The nature of this odd calculus is outlined and justified here. It treats speech communication as having a telegraphic structure. (Non‐linguists normally fail to orient themselves in this field because they treat speech as analogous to telephony.) The telegraph‐code structure of language is examined from top to bottom, and at each of its several levels of complexity (compared to the two levels of Morse code) its structure is shown to be defined by possibilities and impossibilities of combination among the units of that level. Above the highest level we find, instead of such absolute restrictions, conditional probabilities of occurrence: this is the semantic field, outside linguistics, where sociologists can work. Below the lowest level we find, instead of such absolute restrictions, conditional probabilities of phonetic quality: this is the phonetic field, outside linguistics, where physicists can work. Thus linguistics is peculiar among mathematical systems in that it abuts upon reality in two places instead of one. This statement is equivalent to defining a language as a symbolic system; that is, as a code.
22(1950); http://dx.doi.org/10.1121/1.1906675View Description Hide Description
An attempt is made by means of communication theory to build a single conceptual scheme that describes the transmission of messages from one man's brain through the medium of speech into another man's brain. It emphasizes the resemblance of speech production to an encoding process, and the resemblance of the hearing and interpreting of speech sounds to a cryptanalytic procedure that depends on the known conditional probabilities of the language. It is pointed out that speech sounds, or phones, form an infinite, continuous set, while phonemes, the smallest significant units of the cipher, are a discrete small set. It is felt that a logical method of decoding can be set up only through the convergent behavior of language as a statistical process.
22(1950); http://dx.doi.org/10.1121/1.1906681View Description Hide Description
By treating the vocal tract as a series of cylindrical sections, or acoustic lines, it is possible to use transmission line theory in finding the resonances. With constants uniformly distributed along each section, resonances appear as modes of vibration of the tract taken as a whole. Thus, the fundamental mode of the smaller cavity may be affected considerably by a higher mode of the larger; and in addition, higher resonances are found without postulating additional cavities. This is an advantage over the lumped constant treatment, where it is necessary to postulate a different cavity for each resonance, and where the interaction terms in the equation do not include the higher modes of vibration. Under the distributed treatment, dimensions for each vowel may be taken from x‐ray photographs of the vocal tract. The calculations then yield at least three resonances which lie in the frequency regions known for the vowel, from analyses of normal speech. Dependence of the different resonances upon the different cavities is discussed in some detail in the paper.
An electrical circuit based on the transmission line analogy has been made to produce acceptable vowel sounds. This circuit is useful in confirming the general theory and in research on the phoneticeffects of articulator movements. The possibility of using such a circuit as a phonetic standard for vowel sounds is discussed.
22(1950); http://dx.doi.org/10.1121/1.1906682View Description Hide Description
In speechband compression or expansion all the frequencies of the band are divided or multiplied in a certain ratio, but without changing the time dimension. This last requirement makes the problem very difficult because, if we could neglect the time aspect, we could record speech and simply play it back at slower or faster speeds.
I have tried to solve this problem by three different methods: (1) by transformation of the speech frequencies into an optical spectrum and retransformation by light modulation disk and photo‐tube; (2) by use of a string filter; and (3) by use of an ultrasonic cell as a storage device.
22(1950); http://dx.doi.org/10.1121/1.1906685View Description Hide Description
The analysis of speech sound is facilitated if the sound is considered to be the response of a slow‐time‐varying linear system to appropriate excitations. The linear system is characterized by one or more system functions which may be represented most naturally as the sum of complex exponential terms having complex frequencies corresponding to the various formants. Thus, a generalized frequency analysis is made not of the speech wave itself but rather of the system function that shaped that wave. On the other hand, the excitation is best analyzed by autocorrelation methods.
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22(1950); http://dx.doi.org/10.1121/1.1906688View Description Hide Description
This paper presents a short summary of calculations on the vibrations of the cochlear partition (basilar membrane). It is possible to determine the shape, velocity, and amplitude distribution of the traveling waves running from the stapes to the inner ear. Furthermore, it is shown that the calculated vibration pattern is in agreement with observations made on the human cochlea and on models of human inner ears. In particular, analogies between the waves in the inner ear and on the seashore are pointed out. These analogies show the importance of the velocities of propagation for the excitation of the hearingnerve cells.