摘要:

An articulatory model of the tongue composed of linear components was determined by a statistical analysis of tongue shapes and jaw‐opening measured on lateral x‐ray motion pictures. The sum of the four components describes adequately the tongue shapes observed during utterances of 12 French vowels in sentences and of pV1CV2disyllables, where V1V2= [i,a,u] and C = [b,d,g]. These components represent the effect of the jaw articulator, of the tongue‐body articulator, of the dorsal articulator, and of the apical articulator upon the tongue shape, respectively. The vowels plotted on the articulatory space, where thexaxis corresponds to the tongue‐body component and the y axis to the jaw component, form the vowel triangle. The model seems to explain, at least in part, the origin of articulatory “front‐back” and “high‐low” dimensions. We speculate that such model should be suitable for the description of the dynamics of the tongue, since that of the individual articulators may be governed by a relatively simple law.

ISSN:0001-4966    

DOI:10.1121/1.2017158

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

There are abundant data which show the vocal folds to be abducted during closure for intervocalic /p,t,k/ in American English. Vocal‐fold abduction during such stops is reliably indicated by a rapid rise in intraoral pressure following oral occlusion. Recent recordings of intraoral pressure during an adult male English‐speaker's productions of labial and alveolar stops in a variety of environments suggest, however, that vocal‐fold abduction is characteristic only for voiceless stops which precede vowels. Synchronous recordings of intratracheal pressure showed during the closures of stops in all environments that the driving pressure for speech remained appreciably greater than atmosphere. But, during the closures for voiceless stops occurring initially in certain medial consonant clusters, and utterance finally, intraoral pressure generally did not rise above atmosphere. These facts together suggest that /p,t/ in these latter environments were voiceless by virtue of interruption of transglottal flow at the glottis. [Work supported by NSF grant BNS 77‐07686.]

ISSN:0001-4966    

DOI:10.1121/1.2017165

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Over two‐thirds of the fricatives in a sample of 225 languages (Stanford Phonology Archive) occur at places of articulation at or anterior to the palatal region. An even higher preponderance of front fricatives can be seen if /h/, which often functions like a voiceless vowel, is excluded. A partial explanation for the preponderance of front fricatives is the finding of K. Stevens [J. Acoust. Soc. Am.50, 1180–92 (1971)] that there is a generally higher level of energy produced as the place of articulation moves forward in the vocal tract. The synthesis of a number of fricatives using a program that traces the volume velocity wave in the vocal tract and the application of equal loudness contours [based on S. Stevens, J. Acoust. Soc. Am.51, 575–601 (1972)] suggests that net perceived loudness (the spectrum of fricative noised produced with the effect of that spectrum on the auditory system) strongly favors fricatives produced toward the front of the mouth. [Work supported by NIH.]

ISSN:0001-4966    

DOI:10.1121/1.2017171

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Using a linear impedance‐pneumograph taped to the mandible, the mandibular movements for normal and 3 differing types of /s/‐misarticulating children were measured as they spoke sentences containing /s/ in a wide variety of cluster and vowel contexts, with varying stress and juncture, at two differing tempii of production. Simultaneous audio/jaw displacement recordings reveal that the /s/‐defective children, if anything, are somewhat less context sensitive in their /s/‐target positions than are normals, and their abnormal mandible targets for /s/ are as stable as those for normal speaking children. Results are discussed in terms of current speculations concerning defective articulation development.

ISSN:0001-4966    

DOI:10.1121/1.2017174

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Previous studies of short‐term articulatory dynamics have demonstrated that the lips, jaw and tongue act together in a coordinated, synergistic manner and that restraints on one articulator require compensation by others to preserve acoustic contrasts [B. Lindblom and J. Sundberg, J. Acoust. Soc. Am.50, 1166–1179 (1971); C. Riordan, J. Acoust. Soc. Am.62, 998–1002 (1977)]. It has also been shown that the lower lip may move independently of the jaw when required by competing articulatory demands [H. Sussman, P. MacNeilage, and R. Hanson, J. Speech Hear. Res.16, 397–420 (1973)]. The present study explores the possibility that lip and jaw independence may be used to preserve acoustic contrasts in long‐term articulatory compensation for anatomical abnormalities. The lip and jaw movements of two subjects with surgically repaired cleft lip and palate were studied using frame‐by‐frame, pellet‐tracking analysis of a 60 frame/s x‐ray film and acoustic analysis of a simultaneous audio recording. Subjects repeated /əCVCə/ utterances (where C = /p, m/ and V = /i, u, a, æ/) and the data were analyzed from the point of maximal closure for the first consonant, through the vowel to the same point in the second consonant. Results indicate that while the subjects did approximate normal acoustic targets: (1) the upper lip remains immobile; (2) the lower‐lip moves with greater velocity and to a greater extent than expected; and (3) jaw movement was relatively unaffected. These results can presumably be attributed to the anatomical abnormalities and surgical history of the subjects which rendered the upper‐lip an ineffective articulator and caused the lower lip to compensate with faster and larger movements.

ISSN:0001-4966    

DOI:10.1121/1.2017181

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Recent measurements obtained with a variety of techniques have extended von Békésy's observations of cochlear partition mechanics including the traveling wave pattern and the frequency‐place relation. While the cochlear mechanical filter has been shown to be sharper than expected, on the basis of Békésy's results, it apparently is not sharp enough to account for the frequency selectivity observed in auditory nerve fibers. The principal disagreement in the area is whether the vibration of the basilar membrane is linear or nonlinear. Steady‐state nonlinearities that disappear rapidly upon death, transient nonlinear response and two‐tone suppression have been observed in only one species in the mid‐frequency range. Whether this is due to a species difference or a frequency‐place difference remains unresolved.

ISSN:0001-4966    

DOI:10.1121/1.2017185

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

With advances in our understanding of the auditory periphery, models of cochlear mechanics have evolved from descriptions of existing data to the point that they can suggest meaningful observations that should be made and predict expected outcomes. As an example, we discuss relationships among mechanical nonlinearities in the inner ear, two‐tone suppression, and the auditory “second filter.” Electrophysiological two‐tone suppression data indicate that excitatory tuning curves (stimulus intensity required to elicit a specified amount of activity in a primary fiber, as a function of frequency) are more sharply tuned than suppressive tuning curves (stimulus intensity required to suppress the response to a continuous tone at the fiber's characteristic frequency by a specified amount, as a function of frequency). Model simulations which attempt to account for the above difference suggest that there must be a stage of sharpening between the physical variable governing two‐tone suppression (tentatively identified as velocity of the basilar membrane) and the physical variable governing neural excitation. An experiment that would unequivocally demonstrate the simultaneous existence of two representations of the stimulus with significantly different tuning properties in the cochlea is described. The future evolution of cochlear modelling, incorporating nonlinear two‐dimensional models, is discussed.

ISSN:0001-4966    

DOI:10.1121/1.2017187

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Numerous sonic boom studies were accomplished in the last two decades as a result of increased operations of high performance military aircraft, the proposed US/SST, and the anticipated entry of the Concorde into commercial airline service. Much in the way of documentation of the phenomena and its effects was suitably summarized by the society in the first and second Sonic Boom Symposiums of 1965 and 1970, respectively. The present decade has seen a continuation of these efforts, both analytically and experimentally by laboratory and flight tests, in areas such as sonic boom minimization through vehicle design, sonic boom behavior at transonic and low supersonic Mach numbers, and the extension of the predictive schemes to very high altitudes and Mach numbers associated with space launch vehicles such as Space Shuttle. More recently, a renewed interest and concerted effort has been directed towards the long range “over‐the‐top” sonic boom phenomena in the thermosphere in connection with certain “mysterious” noises observed along the east coast. This paper will present an overview, together with a discussion of the latest developments of the sonic boom problem.

ISSN:0001-4966    

DOI:10.1121/1.2017191

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

The time‐domain description of impulsive noise found in industrial environments typically resembles exponentially decaying random noise. The peak sound pressure level (SPL) experienced by the operators of power presses and drop forges generally exceed 100 dB and, in some instances, exceed 150 dB. TheBduration of the impulsive noise produced by these machines ranges from hundredths of a second to a few seconds, and is somewhat dependent on the distance and direction between the machine and the point of observation. LongerBdurations are associated with the greater distances from the machine owing to reverberations. Power circuit breakers can be categorized into three classes in terms of their peak SPL, namely oil, SF6, and air blast. Oil circuit breakers generally produce a lower peak SPL than do the SF6breakers which, in turn, produce a lower peak SPL than do air blast breakers. TheBdurations of the impulsive sounds produced by power circuit breakers is typically 115 ms for air blast breakers, 190 ms for the oil circuit breakers and 240 ms for SF6circuit breakers. The reduction of peak SPL with distance generally follows spherical divergence out to about 1200 ft when propragating inside the switching yard.

ISSN:0001-4966    

DOI:10.1121/1.2017196

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

In recent papers [P. D. Schomer, J. Acoust. Soc. Am.64, 1627–1632 (1978) and P. D. Schomer, J. Acoust. Soc. Am.62, 396–399 (1977)], the author reanalyzed the psychoacoustic data on the annoyance of blast noise to support the use of the US Environmental Protection Agency's blast noise methodology, theC‐weighted day/night level (LCdn), and to prove that the annoyance caused by aLCdnand anA‐weightedLdnof equal magnitude are equivalent. An analysis of the original psychoacoustic data and the recent papers by Dr. Schomer has lead to the conclusion that the two descriptors do not cause equal annoyance. A simple relationship has been derived to equate the two descriptors on an equal annoyance basis. Several statistical distributions of blast noise will be compared to demonstrate the differences in assessment that would result from the application of the US Environmental Protection Agency's methodology, the implied revision, and the relationship derived by the authors of this paper.

ISSN:0001-4966    

DOI:10.1121/1.2017201

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP