摘要:

Learning a new language requires mastering the phonetic as well as lexical and syntactical aspects of the new language. As part of a larger study of second‐language learning, the identification of American English vowels by speakers of Russian and the identification of those speakers’ productions by native speakers of American English were explored. Four adult bilingual Russian/English speakers (two women and two men) participated in this study. The subjects performed two tasks. First, they identified ten English words (ten repetitions of each, presented in random order, of: heed, hid, head, had, hod, hawed, hood, who’d, hud, heard) produced by a native speaker of American English. Then recordings were made of the subjects as they produced four repetitions each, in random order, of these ten English words. These recordings were digitized using SoundDesigner II software with an audiomedia board on a Macintosh Quadra 800 computer. Listening tapes will be prepared, using SoundDesigner II software, for identification of the Russian speakers’ vowels by native American English speakers. The results of the identification of the Russian speaker’s vowels will be compared with the identification of American English vowels by the native Russian speakers. [Work supported by St. John’s University.]

ISSN:0001-4966    

DOI:10.1121/1.422949

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

摘要:

An investigation of the acoustic correlates of stress or accent in infant vocalizations was undertaken using five English‐ and five French‐learning participants at two developmental points, the onset of word use (10–13 months) and late in the single‐word period (14–19 months). A data base of 555 disyllabic utterances (words and babble) was digitized from naturalistic recordings and quantified acoustically by indices of duration, amplitude, and fundamental frequency (F0). Cluster analysis as well as the results of perceptual judgments (i.e., both a bottom‐up and a top‐down approach) revealed a developmental trend toward the adult prosodic system. In addition, acoustic comparisons of French and American infants at both developmental points revealed differences in their use of amplitude,F0, and duration to accent a syllable. The differences were traceable to the adult patterns for the respective adult languages. These results suggest that infants’ perceptual attunement to prosody in the prelinguistic period manifests itself in the beginnings of adultlike production as early as the onset of word use. [Work supported in part by the UK Economic and Social Research Council.]

ISSN:0001-4966    

DOI:10.1121/1.422953

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

摘要:

A new iterative solution to the problem of sea surface scattering is obtained which has the Kirchhoff approximation as its leading term. This solution is obtained by transforming an integral equation of the first kind for the surface potential to one of the second kind, and applying the method of successive approximations. The advantages of this method are that the conditions under which this solution converges may be readily established and the solution may be iterated to sufficiently high order in the interaction to examine the rate at which it converges. A numerical example of scattering from an echelette grating is considered, and the regime of convergence established. It is found that the new iterative solution converges only for such surfaces on whichkσσ′<π wherekis the wave number of the scattered radiation and σ and σ′are, respectively, the rms surface height and slope. This finding raises doubts concerning the regime in which the Kirchhoff approximation is traditionally deemed applicable. Finally, numerical studies are presented to illustrate the convergence of the iterative solution.

ISSN:0001-4966    

DOI:10.1121/1.422958

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

摘要:

Every reverberation experiment done in shallow water is by its nature, bistatic at long ranges. That is to say, in addition to simple monostatic returns, the received signal is composed of energy arriving along bottom bounce paths for which incident and scattered angles are different. Therefore, it is possible to measure in‐plane bistatic scattering strength using a monostatic geometry [Hines, Crowe, and Ellis, J. Acoust. Soc. Am. (in review)]. Noting this, a simple array consisting of a pair of free‐flooding‐ring projectors and two hydrophones was used to measure monostatic and bistatic scatter in 100 m of water on the Scotian Shelf. A series of linear FM (LFM) pulses was transmitted in four frequency bands over the range 900 to 2100 Hz. The reverberation data between the first bottom return and the first surface return provided estimates of monostatic backscatter strength for grazing angles down to 10°. Data arriving after the first‐bottom–first‐surface interaction provided estimates of in‐plane bistatic scattering strength for pairs of incident and scattered grazing angles (φi, φs) down to (7°, 57°). In this paper, the experiment and data are described in light of the monostatic and bistatic arrivals.

ISSN:0001-4966    

DOI:10.1121/1.422963

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

摘要:

Sound propagation at mid to high frequencies (1–20 kHz) in shallow‐water environments is extremely complicated, variable, and poorly understood due to multiple processes that cover a wide range of temporal and spatial scales. Numerical simulations using a full‐wave PE model are carried out to interpret the acoustic data taken during very carefully designed experiments at a shallow‐water site inside the Delaware Bay. Records of broadband acoustic wave time series (from hours to days) are numerically reproduced by using the collected environmental data as input to the PE model. The statistics of both measured and simulated multipath signals are calculated and compared in the presence of rough sea‐surface scattering and surface bubble layer attenuation. The surface wind effects can be separated from the slowly varying volume fluctuations of sound speed, by comparing the temporal variations; while it can be separated from the bottom effects by examining different multipath arrivals. The dependence of coherence on the parameters of wind strength and acoustic frequency is examined.

ISSN:0001-4966    

DOI:10.1121/1.422969

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP