摘要:

Measurements were made of closure durations of the eighteen possible voiced‐voiceless and voiceless—voiced combinations of /p/, /t/, /k/ and /b/, /d/, /g/ produced medially in isolated nonsense disyllables by three English‐speaking males. Preliminary results show that closure durations depend on both voicing and place of articulation of first and second members of such clusters. Mean closure durations were significantly longer (by approximately 20 msec) for voiceless‐voiced than voiced—voiceless clusters. Clusters with first‐member velars were longer than those with first‐member labials and alveolars, while clusters with second‐member velars were shorter than those with other second members. Sequences of stops requiring the greatest changes in points of articulation (labial → velar, or velar → labial) were longer than sequences requiring smaller changes in the same direction (labial → alveolar, alveolar → velar, or velar → alveolar, alveolar → labial). Closure durations generally varied inversely with durations of surrounding vowels. Clusters were longest, for example, in the frame /pI__It/, somewhat shorter in/pI__at/, shorter still in /pa__It/, and shortest in /pa__at/. But, durations for like clusters were no shorter in the frame /pI__Id/ than in /pI__It/. These latter findings suggest first that closure durations for medial step clusters are governed extrinsically by a tendency toward isochrony. However, whatever principles lead toward isochrony appear to operate before the rule which results in greater length of final‐syllable vowels before voiced stops in English.

ISSN:0001-4966    

DOI:10.1121/1.2015975

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

When a single higher order model is generated in a rigid rectangular or narrow annular duct, at high enough intensities, generation of higher harmonics is observed. In the case of multimode inputs, the author and his collegues have shown theoretical results indicating the existence of strong acoustic—acoustic interactions at the first order of the perturbation scheme. This interaction would lead to energy being fed into both higher and lower harmonics. In this paper experimental results are presented, using a spinning mode synthesizer, which varify the theoretical predictions. Implications of these results for some of the practical problems have been discussed.

ISSN:0001-4966    

DOI:10.1121/1.2015982

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

Recently I have improved apparatus for the acoustic levitation of a drop of one liquid in another, making it practical to build for anyone who has an oscillaior and audio amplifier with response to 50 kHz, a current probe, an inexpensive oscilloscope, and a lead zirconate titanate cylinder of the right size. This piezoelectric cylinder (1.5‐in. o.d. and length, 0.125‐in. thickness) is epoxied near the center of a foot long piece of standard 30‐mm o.d. pyrex tube. A hollow piston with o‐ring seal and O. 005‐in. diaphragm acts as an excellent bottom, pressure‐release reflector of acoustic energy, as is the top air—liquid interface, leading to strong acoustic standing waves at particular resonance frequencies. Optimum frequencies are determined by observing the input current to the transducer as the oscillator is tuned between 47 and 55 kHz, and as liquid and piston levels are adjusted. Benzene droplets in water have been levitated with only a fraction of a watt input to the transducer. More details of this simple system will be described. [Work supported by U. S. Office of Naval Research and NSF, Heat Transfer Program.]

ISSN:0001-4966    

DOI:10.1121/1.2015987

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

Temporal integration of tone glides in frequency ranges corresponding to first and second formant regions of speech were reported at the previous meeting of the Society [M. J. Collins and J. K. Cullen, Jr., J. Acoust. Soc. Am.60. S48 (A) (1976); Nabelek, J. Acoust. Soc. Am.60, S48 (A) (1976)]. These studies demonstrated a slower rate of integration for tone glides for fixed frequencies, with an asymmetry between functions for rising and falling glides. The current investigation extends these observations to combined tone glides in the frequency ranges 200–700 and 1200–1700 Hz. Integration of all possible glide combinations was investigated for durations of 5–120 msec. Results indicate an asymmetry in the integration functions for sets where both glides rose and both glides fell, with mixed glide sets yielding intermediate functions independent of which glide rose or fell. Thresholds for detection suggest partial summation occurs across glide components even though instantaneous frequency values are separated by more than a conventional critical band. [Work supported in part by NIH and the Sloan Foundation.]

ISSN:0001-4966    

DOI:10.1121/1.2015993

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

Several Old World monkeys (M.fascicularis) have demonstrated their ability to remember, after delay intervals of many secs., various sequences of acoustic stimuli. Both the nature of a given sequence as well as the order of the two elements which comprised it were shown routinely by the animals to have been retained at>90% correct response levels during months of daily test sessions [J. H. Dewson III, Acoust. Soc. Am.57, S11 (A) (1975)]. Detailed analysis of the errors made on this complex conditional match‐to‐sample task reveals the effects on memory of strong proactive interference (PI) when the elements of a sequence are of equal (0.5 sec) duration. By selectively altering the relative durations of the two elements, the situation can be reversed to one in which retroactive interference (RI) is clearly shown. This demonstration of PI and of RI in individual animal subjects, obtainable within single testing sessions, provides an indication of basic similarity of memory processes across the primate order.

ISSN:0001-4966    

DOI:10.1121/1.2015994

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

Auditory evoked potentials (AEP) were recorded for a 500‐msec period from the temporal language processing areas of the left (LH) and right hemispheres (RH) of 6 male and 6 female four‐year‐old children in response to 4 synthetically generated bilabial stop consonants with voice onset time (VOT) values of 0, +20, +40, and +60 msec. AEPs were averaged for each VOT condition and then factor analyzed [Molfese, 1976]. Four factors accounting for 65% of the total variance were extracted. Factor scores for these orthogonal factors were then submitted to a 2(sex) × 2(Hemisphere) × 4 (VOT) ANOVA. In this way, components of the brain‐response were identified which reflected the following: (1) sensitivity to VOT changes that crossed the phoneme boundary (F= 11.82, df + 3, 80,p<0.01), (2) specific RH involvement in the categorical perception process (F= 3.58, df = 3, 30,p<0.05), (3) sex differences in RH activity (F= 6.24, df = 1, 10,p<0.05), and (4) general hemisphere differences (F= 8.77, df = 1, 10,p<0.01). These results support the notion that speech perception is a multidimensional process dependent on mechanisms within both hemispheres. Developmental issues are also addressed.

ISSN:0001-4966    

DOI:10.1121/1.2016000

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP