Deficits in Pre-attentive Processing of Spatial Location and Negative Symptoms in Subjects at Clinical High Risk for Schizophrenia

Deficits in mismatch negativity (MMN) generation are among the best-established biomarkers for cognitive dysfunction in schizophrenia and predict conversion to schizophrenia (Sz) among individuals at symptomatic clinical high risk (CHR). Impairments in MMN index dysfunction at both subcortical and cortical components of the early auditory system. To date, the large majority of studies have been conducted using deviants that differ from preceding standards in either tonal frequency (pitch) or duration. By contrast, MMN to sound location deviation has been studied to only a limited degree in Sz and has not previously been examined in CHR populations. Here, we evaluated location MMN across Sz and CHR using an optimized, multi-deviant pattern that included a location-deviant, as defined using interaural time delay (ITD) stimuli along with pitch, duration, frequency modulation (FM) and intensity deviants in a sample of 42 Sz, 33 CHR and 28 healthy control (HC) subjects. In addition, we obtained resting state functional connectivity (rsfMRI) on CHR subjects. Sz showed impaired MMN performance across all deviant types, along with strong correlation between MMN deficits and impaired neurocognitive function. In this sample of largely non-converting CHR subjects, no deficits were observed in either pitch or duration MMN. By contrast, CHR subjects showed significant impairments in location MMN generation particularly over right hemisphere and significant correlation between impaired location MMN and negative symptoms including deterioration of role function. In addition, significant correlations were observed between location MMN and rsfMRI involving brainstem circuits. In general, location detection using ITD stimuli depends upon precise processing within midbrain regions and provides a rapid and robust reorientation of attention. Present findings reinforce the utility of MMN as a pre-attentive index of auditory cognitive dysfunction in Sz and suggest that location MMN may index brain circuits distinct from those indexed by other deviant types.

Experimental-Phonetic Analysis of Suprasentential Units in the English Language

The current article deals mainly with the suprasentential units in English and their characteristic peculiarities. Some viewpoints of western, Russian and Azerbaijani linguists are discussed here. One of the important matters discussed here is to distinguish the notions “text” and “suprasentential units”, which was possible owing to the viewpoints and investigations of specialists in this field. To determine “suprasentential units”, some other terms such as, “micro-text” and “macro-text” are discussed here, too. To get a detailed information on “suprasentential units”, phonetic experiment was carried out. The essence of the article is to determine the phoneticparameters of “suprasentential units” in the form of a short text. The experiment was realised at the Institute of Linguistics of the National Academy of Sciences of Azerbaijan. For acoustic analysis of the recorded materials, “Speech Analyser”, “WinCecil”, “PRAAT”, “MacSpeech Lab” programs have been used. In the acoustic analysis of speech signals of the given short text, the valuable “PRAAT” computer program created by the professors of Amsterdam University Paul Boersman and David Veenik has been widely used. “PRAAT” computer program has wide opportunities, such as to hold ossillographic and spectographic analysis of language materials (in our case, short texts), to get indicators of tonal frequency intensity, and length of language materials, etc. The above mentioned computer program provides specialists and learners with the chance of learning speech fragments having the recording time from several m/sec to several hours.

Tonal signal detection in passive sonar systems using atomic norm minimization

Frequency estimation of a tonal signal in passive sonar systems is crucial to the identification of the marine object. In the conventional techniques, a basis mismatch error caused by the discretization of the frequency domain is unavoidable, resulting in a severe degradation of the object detection quality. To overcome the basis mismatch error, we propose a tonal frequency estimation technique in the continuous frequency domain. Towards this end, we formulate the frequency estimation problem as an atomic norm minimization problem. From the numerical experiments, we show that the proposed technique is effective in identifying the tonal frequency components of marine objects.

Analytical and Numerical Investigations on the Aeroacoustical Oscillation of Flow Past the Cavity

Noise radiated by aeroacoustical oscillation of low Mach number flow past a two-dimensional cavity has been investigated analytically and numerically using electro-acoustical analogy and a hybrid scheme combining CFD with an implementation of the porous Ffowcs Williams-Hawkings equation. The noise generation mechanism is illustrated and the interaction between flow and cavity as well as key factors of resonant frequency is discussed. The 2D compressible unsteady Reynolds averaged Navier-Stokes equations (URANS) are solved to obtain near field acoustic source and unsteady characteristics of cavity flow. A buffer domain is exerted along all external boundaries to suppress boundary wave reflection. Computed tonal frequency and amplitude of pressure oscillations demonstrate good agreement with previous computational simulations and experiments. The influences of the length and shape of the neck and porous inserts on the noise radiated to the far field are also investigated. The 3D far field numerical results show that at a certain incoming flow velocity and shear layer thickness the frequency of the dominant oscillation increases with the length of the neck and the magnitude in the downstream far field is 8dB greater than that in the upstream far field. The increasing chamfer decreases the resonance frequency and changes the effective streamwise opening length resulting in significant differences in acoustic pressure fluctuation. The porous inserts on the floor of the cavity reduce the mass flow flux through the cavity neck and accordingly suppress the amplitude of dominant oscillation. The preliminary simulations reveal promising methods for sound radiation control.

Design Principles of Controlling Vehicle Gear Whine Noise Based on Loudness Metric

In-vehicle noise is composed of a variety of tonal (frequency-related) components and the tonal components play an important role in the improvement of sound quality for interior vehicle noise. Among them, gear whine noise is the key contributor to total in-vehicle noise and gain a lot of researchers interest. Through their effort, thespl (dBA)is relatively low. However, customers still perceive the tonal components and complain about the vehicle quality. Therefore a better understanding of how tonal components are perceived is necessary for automotive gear transmission designers. In this study, firstly, gear dynamic behavior is briefly introduced to get the gear noise spectrum. Secondly, human hearing mechanism to different tonal components is summed. Then loudness case studies are conducted. Finally, some basic design principles of controlling gear whine noise are proposed based on the results.