The role of release bursts in the perception of [s]-stop clusters

The role of the release burst as a cue to the perception of stop consonants following [s] was investigated in a series of studies. Experiment 1 demonstrated that silent closure duration and burst duration can be traded as cues for the "say"-"stay" distinction. Experiment 2 revealed a similar trading relation between closure duration and burst amplitude. Experiments 3 and 4 suggested, perhaps surprisingly, that absolute, not relative, burst amplitude is important. Experiment 5 demonstrated that listener's sensitivity to bursts in a labeling task is at least equal to their sensitivity in a burst detection task. Experiments 6 and 7 replicated the trading relation between closure duration and burst amplitude for labial stops in the "slit"-"split" and "slash"-"splash" distinctions, although burst amplification, in contrast to attenuation, had no effect. All experiments revealed that listeners are remarkably sensitive to the presence of even very weak release bursts.     

Coexistence of Two Different Distorted Octahedral [MnF6]3− Sites in K3[MnF6]: Manifestation in Spectroscopy and Magnetism

As a consequence of the static Jahn-Teller effect of the ⁵E ground state of Mn^III in cubic structures with octahedral parent geometries, their octahedral coordination spheres become distorted. In the case of six fluorido ligands, [MnF₆]³⁻ anions with two longer and four shorter Mn−F bonds making elongated octahedra are usually observed. Herein, we report the synthesis of the compound K₃[MnF₆] through a high-temperature approach and its crystallization by a high-pressure/high-temperature route. The main structural motifs are two quasi-isolated, octahedron-like [MnF₆]³⁻ anions of quite different nature compared to that met in ideal octahedral Mn^III Jahn-Teller systems. Owing to the internal electric field of C_i symmetry dominated by the next-neighbour K⁺ ions acting on the Mn^III sites, both sites, the pseudo-rhombic (site 1) and the pseudo-tetragonally elongated (site 2) [MnF₆]³⁻ anions are present in K₃[MnF₆]. The compound was characterized by single-crystal and powder X-ray diffraction, and magnetometry as well as by FTIR, Raman, and ligand field spectroscopy. A theoretical interpretation of the electronic structure and molecular geometry of the two Mn sites in the lattice is given by using a vibronic coupling model with parameters adjusted from multireference ab-initio cluster calculations.     

Scanning tunneling spectroscopy of Cl vacancies in NaCl films: strong electron-phonon coupling in double-barrier tunneling junctions

Broad Gaussian line shapes are observed in scanning tunneling spectroscopy of single, localized electronic states induced by Cl vacancies in ultrathin NaCl films on Cu surfaces. Using a simple inelastic resonance tunneling model, we show that the observed broad line shapes are caused by a strong coupling between the localized state and the optical phonons in the film. The parameters for the model are obtained from density functional calculations, in which the occupation of the vacancy state temporarily taking place in the experiment has also been accounted for.     

Perception of the [m]-[n] distinction in CV syllables

The contribution of the nasal murmur and the vocalic formant transitions to perception of the [m]-[n] distinction in utterance-initial position preceding [i,a,u] was investigated, extending the recent work of Kurowski and Blumstein [J. Acoust. Soc. Am. 76, 383-390 (1984)]. A variety of waveform-editing procedures were applied to syllables produced by six different talkers. Listeners' judgments of the edited stimuli confirmed that the nasal murmur makes a significant contribution to place of articulation perception. Murmur and transition information appeared to be integrated at a genuinely perceptual, not an abstract cognitive, level. This was particularly evident in [-i] context, where only the simultaneous presence of murmur and transition components permitted accurate place of articulation identification. The perceptual information seemed to be purely relational in this case. It also seemed to be context specific, since the spectral change from the murmur to the vowel onset did not follow an invariant pattern across front and back vowels.     

On the possible role of auditory short-term adaptation in perception of the prevocalic [m]-[n] contrast

Acoustic information about the place of articulation of a prevocalic nasal consonant is distributed over two distinct signal portions, the nasal murmur and the onset of the following vowel. The spectral properties of these signal portions are perceptually important, as is their relationship (the pattern of spectral change). A series of experiments was conducted to investigate to what extent relational place of articulation information derives from a peripheral auditory interaction, viz., short-term adaptation caused by the murmur. Experimental manipulations intended to disrupt the effects of such adaptation included separation of the murmur and the vowel by intervals of silence, presentation to different ears, and reversal of order. Other tests of the possible role of adaptation included manipulation of murmur duration, murmur-vowel cross splicing, and high-pass filtering of the excised vowel onset. While the results of several experiments were compatible with the peripheral adaptation hypothesis, others did not support it. An alternative hypothesis, that the manner cues provided by the murmur are crucial for accurate place judgments, was also discredited. It was concluded that, at least under good listening conditions, the perception of spectral relationships does not depend on peripheral auditory enhancement and probably rests on a central comparison process.     

Memory recall in arousing situations – an emotional von Restorff effect?

Background  

Previous research has demonstrated a relationship between memory recall and P300 amplitude in list learning tasks, but the variables mediating this P300-recall relationship are not well understood. In the present study, subjects were required to recall items from lists consisting of 12 words, which were presented in front of pictures taken from the IAPS collection. One word per list is made distinct either by font color or by a highly arousing background IAPS picture. This isolation procedure was first used by von Restorff. Brain potentials were recorded during list presentation.     

New method for parameter estimation in probabilistic models: minimum probability flow

Fitting probabilistic models to data is often difficult, due to the general intractability of the partition function. We propose a new parameter fitting method, minimum probability flow (MPF), which is applicable to any parametric model. We demonstrate parameter estimation using MPF in two cases: a continuous state space model, and an Ising spin glass. In the latter case, MPF outperforms current techniques by at least an order of magnitude in convergence time with lower error in the recovered coupling parameters.     

Perception of the [m]-[n] distinction in VC syllables

This study complements earlier experiments on the perception of the [m]-[n] distinction in CV syllables [B. H. Repp, J. Acoust. Soc. Am. 79, 1987-1999 (1986); B. H. Repp, J. Acoust. Soc. Am. 82, 1525-1538 (1987)]. Six talkers produced VC syllables consisting of [m] or [n] preceded by [i, a, u]. In listening experiments, these syllables were truncated from the beginning and/or from the end, or waveform portions surrounding the point of closure were replaced with noise, so as to map out the distribution of the place of articulation information for consonant perception. These manipulations revealed that the vocalic formant transitions alone conveyed about as much place of articulation information as did the nasal murmur alone, and both signal portions were about as informative in VC as in CV syllables. Nevertheless, full VC syllables were less accurately identified than full CV syllables, especially in female speech. The reason for this was hypothesized to be the relative absence of a salient spectral change between the vowel and the murmur in VC syllables. This hypothesis was supported by the relative ineffectiveness of two additional manipulations meant to disrupt the perception of relational spectral information (channel separation or temporal separation of vowel and murmur) and by subjects' poor identification scores for brief excerpts including the point of maximal spectral change. While, in CV syllables, the abrupt spectral change from the murmur to the vowel provides important additional place of articulation information, for VC syllables it seems as if the format transitions in the vowel and the murmur spectrum functioned as independent cues.