124,885 research outputs found
Subphonemic and suballophonic consonant variation : the role of the phoneme inventory
Consonants exhibit more variation in their phonetic realization than is typically acknowledged, but that variation is linguistically constrained. Acoustic analysis of both read and spontaneous speech reveals that consonants are not necessarily realized with the manner of articulation they would have in careful citation form. Although the variation is wider than one would imagine, it is limited by the phoneme inventory. The phoneme inventory of the language restricts the range of variation to protect the system of phonemic contrast. That is, consonants may stray phonetically into unfilled areas of the language's sound space. Listeners are seldom consciously aware of the consonant variation, and perceive the consonants phonemically as in their citation forms. A better understanding of surface phonetic consonant variation can help make predictions in theoretical domains and advances in applied domains
A Simple Converse of Burnashev's Reliability
In a remarkable paper published in 1976, Burnashev determined the reliability
function of variable-length block codes over discrete memoryless channels with
feedback. Subsequently, an alternative achievability proof was obtained by
Yamamoto and Itoh via a particularly simple and instructive scheme. Their idea
is to alternate between a communication and a confirmation phase until the
receiver detects the codeword used by the sender to acknowledge that the
message is correct. We provide a converse that parallels the Yamamoto-Itoh
achievability construction. Besides being simpler than the original, the
proposed converse suggests that a communication and a confirmation phase are
implicit in any scheme for which the probability of error decreases with the
largest possible exponent. The proposed converse also makes it intuitively
clear why the terms that appear in Burnashev's exponent are necessary.Comment: 10 pages, 1 figure, updated missing referenc
Local thermal energy as a structural indicator in glasses
Identifying heterogeneous structures in glasses --- such as localized soft
spots --- and understanding structure-dynamics relations in these systems
remain major scientific challenges. Here we derive an exact expression for the
local thermal energy of interacting particles (the mean local potential energy
change due to thermal fluctuations) in glassy systems by a systematic
low-temperature expansion. We show that the local thermal energy can attain
anomalously large values, inversely related to the degree of softness of
localized structures in a glass, determined by a coupling between internal
stresses --- an intrinsic signature of glassy frustration ---, anharmonicity
and low-frequency vibrational modes. These anomalously large values follow a
fat-tailed distribution, with a universal exponent related to the recently
observed universal density of states of quasi-localized
low-frequency vibrational modes. When the spatial thermal energy field --- a
`softness field' --- is considered, this power-law tail manifests itself by
highly localized spots which are significantly softer than their surroundings.
These soft spots are shown to be susceptible to plastic rearrangements under
external driving forces, having predictive powers that surpass those of the
normal-modes-based approach. These results offer a general,
system/model-independent, physical-observable-based approach to identify
structural properties of quiescent glasses and to relate them to glassy
dynamics.Comment: 8 pages, 4 figures + Supporting Information, shorter title, minor
textual change
Continuous Interaction with a Virtual Human
Attentive Speaking and Active Listening require that a Virtual Human be capable of simultaneous perception/interpretation and production of communicative behavior. A Virtual Human should be able to signal its attitude and attention while it is listening to its interaction partner, and be able to attend to its interaction partner while it is speaking â and modify its communicative behavior on-the-fly based on what it perceives from its partner. This report presents the results of a four week summer project that was part of eNTERFACEâ10. The project resulted in progress on several aspects of continuous interaction such as scheduling and interrupting multimodal behavior, automatic classification of listener responses, generation of response eliciting behavior, and models for appropriate reactions to listener responses. A pilot user study was conducted with ten participants. In addition, the project yielded a number of deliverables that are released for public access
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