Quiet Conditions Research Articles

The Relationship between Contralateral Suppression of Transient Evoked Otoacoustic Emission and Unmasking of Speech Evoked Auditory Brainstem Response

Introduction Several studies have shown that efferent pathways of the auditory system improve perception of speech-in-noise. But, the majority of investigations assessing the role of efferent pathways on speech perception have used contralateral suppression of otoacoustic emissions as a measure of efferent activity. By studying the effect of efferent activity on the speech-evoked auditory brainstem response (ABR), some more light could be shed on the effect of efferent pathways on the encoding of speech in the auditory pathway. Objectives To investigate the relationship between contralateral suppression of transient evoked otoacoustic emission (CSTEOAE) and unmasking of speech ABR. Methods A total of 23 young adults participated in the study. The CSTEOAE was measured using linear clicks at 60 dB peSPL and white noise at 60 dB sound pressure level (SPL). The speech ABR was recorded using the syllable /da/ at 80 dB SPL in quiet, ipsilateral noise, and binaural noise conditions. In the ipsilateral noise condition, white noise was presented to the test ear at 60 dB SPL, and, in the binaural noise condition, two separate white noises were presented to both ears. Results The F0 amplitude of speech ABR was higher in quiet condition; however, the mean amplitude of F0 was not significantly different across conditions. Correlation analysis showed a significant positive correlation between the CSTEOAE and the magnitude of unmasking of F0 amplitude of speech ABR. Conclusions The findings of the present study suggests that the efferent pathways are involved in speech-in-noise processing.

Cochlear Implantation Improves Both Speech Perception and Patient-Reported Outcomes: A Prospective Follow-Up Study of Treatment Benefits among Adult Cochlear Implant Recipients.

Cochlear implantation is considered the best treatment option for patients with severe-to-profound sensorineural hearing loss for whom conventional hearing aids are insufficient. We used a repeated measures longitudinal approach to evaluate speech recognition and patient-reported outcomes after cochlear implantation in an unbiased cohort of Danish adult patients in a prospective cohort study. We assessed 39 recipients before and two times after implantation using a battery of tests that included Dantale I, the Danish Hearing in Noise Test, the Nijmegen Cochlear Implant Questionnaire, and the Speech, Spatial, and Qualities of Hearing Scale. The study group improved significantly on all outcome measures following implantation. On average, Dantale I scores improved by 29 percentage points and Hearing in Noise Test scores improved by 22 percentage points. Most notably, the average Dantale score improved from 26 to 70% in the CI in quiet condition and from 12 to 42% in the cochlear implantation in noise condition when tested monaurally. Dantale demonstrated a significant positive correlation with Nijmegen Cochlear Implant Questionnaire and Speech, Spatial, and Qualities of Hearing Scale scores, while Hearing in Noise Test had no significant correlation with the patient-reported outcome measures. Patients improved significantly at 4 months and marginally improved further at 14 months, indicating that they were approaching a plateau. Our study’s use of audiometric and patient-reported outcome measures provides evidence of the treatment benefits of cochlear implantation in adults, which may help physicians advise patients on treatment decisions and align treatment benefit expectations, as well as serve as a foundation for the development of new cochlear implantation selection criteria.

Detection of Solar Flares from the Analysis of Signal-to-Noise Ratio Recorded by Digisonde at Mid-Latitudes

This work proposes a new indirect method to detect the impact of solar flares on ionospheric sounding measurements, i.e., on the signal-to-noise ratio of ionospheric reflected radio signals. The method allows us to detect and characterize the ionospheric absorption of high-frequency radio waves as a product of these energetic events. The detection is based on the estimation of the quiet conditions signal-to-noise ratio (SNR) pattern of the month and the subsequent comparison of this pattern with the SNR for the analyzed day. The method has been tested by using data from Ebro Observatory ionospheric station (DPS4D, EB040), but it can be applied to any other ionospheric station. At EB040, it can provide observational data to the international Service of Rapid Magnetic Variations (SRMV) to help confirm Sfe (Solar Flare Effects). To set up the method, we considered a data set of 262 solar flares that occurred during 2011–2014 and were observed during daylight hours at EB040 (17 X-class, 124 M-class, and 121 C-class). This led to impose a threshold of −20 dB in the SNR for at least four consecutive frequencies to confirm that a solar flare took place. The method is particularly sensitive for the detection of X-class solar flares, performs quite well with M-class events, and is even able to detect some C-class flares with high solar altitude angles. Furthermore, we studied some constraints that affect the detection of solar flares from the analysis of GOES-15 hard X-ray flux data about the considered events. For each flare, we computed its solar altitude angle at the time of the ionospheric sounding to get an estimation of its geoeffective irradiance, which had an effect on the local ionosphere. We can confirm that the method of detection is more effective with flares that present a solar elevation angle higher than 18.94°, a geoeffective hard X-ray irradiance above 3.30 × 10−6 W/m2, and a geoeffective hard X-ray radiant exposure higher than 1.61 × 10−3 J/m2, computed during the 5 min preceding the ionospheric sounding.

Non-thermal escape of the martian CO[formula omitted] atmosphere over time: Constrained by Ar isotopes

The ion escape of Mars’ CO2 atmosphere caused by its dissociation products C and O atoms is simulated from present time to ∼4.1 billion years ago (Ga) by numerical models of the upper atmosphere and its interaction with the solar wind. The planetward-scattered pick-up ions are used for sputtering estimates of exospheric particles including 36Ar and 38Ar isotopes. Total ion escape, sputtering and photochemical escape rates are compared. For solar EUV fluxes ≥3 times that of today’s Sun (earlier than ∼2.6 Ga) ion escape becomes the dominant atmospheric non-thermal loss process until thermal escape takes over during the pre-Noachian eon (earlier than ∼4.0–4.1 Ga). If we extrapolate the total escape of CO2-related dissociation products back in time until ∼4.1 Ga we obtain a maximum theoretical equivalent to CO2 partial pressure of more than ∼0.4 bar through non-thermal escape during quiet solar wind conditions. However, surface–atmosphere interaction and/or extreme solar events such as frequent CMEs could have increased this value even further. By including the surface as a sink, up to 0.9bar, or even up to 1.8bar in case of hidden carbonate reservoirs, could have been present at 4.1Ga The fractionation of 36Ar/38Ar isotopes through sputtering and volcanic outgassing from its initial chondritic value of 5.3, as measured in the 4.1 billion years old Mars meteorite ALH 84001, until the present day, however, can be reproduced for assumed CO2 partial pressures of ∼0.01–0.4bar without, and ∼0.4–1.8bar including surface sinks, and depending on the cessation time of the Martian dynamo (assumed between 3.6 and 4.0 Ga) — if atmospheric sputtering of Ar started afterwards.

One day ahead prediction of global TEC using Pix2pixhd

In this paper, we make a 1-day forecasting of global total electron content (TEC) using pix2pixhd that is a novel deep learning method based on GAN. For training, we use the International GNSS Service (IGS) TEC maps from 2003 to 2018, covering the entire solar cycle with a training set (2003–2013), a validation set (2018), and a test set (2014–2017). Then we evaluate our model using Root Mean Square Error (RMSE) and Correlation Coefficient (CC) and compare our model with IRI-2016. As a result, our model shows a good performance for TEC forecast with one day in advance. From the average difference between output maps of our model and target ones (+1 day IGS TEC maps) as well as between IRI TEC maps (+1 day) and target ones and corresponding standard deviations, our model behaves better than IRI at a global scale, especially at low latitudes. Under different conditions of geomagnetic and solar activities, the prediction effect of our model is always better than IRI. Our model behaves well during geomagnetic quiet conditions, but is affected during geomagnetic storms showing stronger deviations. Besides, our model behaves better during solar maximum than minimum days. Our work demonstrates a new possibility for the application of deep learning on a broader field of geosciences, particularly for problems of prediction.

‘Musical effort’ and ‘musical pleasantness’: a pilot study on the neurophysiological correlates of classical music listening in adults normal hearing and unilateral cochlear implant users

Objective This pilot case-control study is aimed to estimate ‘musical effort’ and ‘musical pleasantness’ in adults normal hearing (NH) and Unilateral Cochlear Implant (UCI) users via neurophysiological indices and a cognitive-behavioural approach. Methods 7 NH and 7 UCI subjects underwent electroencephalographic (EEG) recording with two EEG indices, Approach Withdrawal (AW) and Workload (WI), and behavioural tests conducted during a forced-choice musical emotion recognition task performed in quiet and noise in two emotional conditions. Results Musical effort in terms of WI did not vary between conditions and groups. Inversely, for AW, statistically significant differences in noisy conditions were observed between groups, indicating a difficulty for the patients in discriminating the musical pleasantness in noise. However, self-reported data suggest the ability of UCI to cognitively evaluate the stimulus in terms of both auditory difficulty and pleasantness. Conclusion Findings suggest the possible relevance of the Cochlear Implant in supporting the patients’ effort in listening to music in noise, allowing a pleasant enjoyment in the quiet condition. Overall, this study appears worthy of interest and paves the way for further investigation by providing data on the neurophysiological perception of music.

Detection of Periodic Disturbances in LOFAR Calibration Solutions

The Earth’s ionosphere is a highly variable medium on a wide range of spatio-temporal scales. The responsiveness of plasma to the geomagnetic field and its changes gives rise to anisotropy, which may introduce wave-like characteristics while scanning the ionosphere with a line-of-sight towards a radio source. Previous studies of LOw Frequency ARray (LOFAR) calibration phase solutions report that the estimated beta parameter of a structure function calculated over 6–8 h of astronomical observation timespan has a range of values from 1.6 to 2.0, with an average of 1.89. Such difference between the observations could result from transient wave-like disturbances within the data. This study aims to present a method of signal processing of ionospheric calibration datasets that allows the extraction of a transient wave-like signal and discuss its possible origin. We use complex Morlet wavelet analysis applied to two 8 h observations corresponding to very quiet geomagnetic conditions. We find a wave-like signal in the interferometric Total Electron Content data even during periods of no geomagnetic activity. We suggest it results from the relative velocity changes between the LOFAR line-of-sight and a convection pattern in the ionospheric F layer. Establishing the relationship between quiet time ionosphere, geomagnetic field changes and LOFAR’s calibration solutions may prove beneficial to determination of the dominant signals in the more disturbed conditions, which we leave for future study.

Effects of two-talker child speech on novel word learning in preschool-age children

Preschool-age children’s recognition of speech is more susceptible to the presence of background noise than that of older children. Because younger children rely on access to speech to learn their native language, children who are poorer at resolving degraded speech may be at risk for delayed vocabulary development. To test this relation directly, we are implementing a retrieval-based word learning task in preschool-age children. Children are taught four novel disyllabic words either in a quiet condition or in the presence of two-talker child speech (TTS) at + 10 dB-signal-to-noise ratio. Children’s performance is quantified by the number of words and the number of phonological features recalled immediately after training and after a 5-min delay. Children also complete tests of familiar word recognition in TTS, verbal working memory, and vocabulary knowledge. In this presentation, we will compare children’s word-learning outcomes between the quiet and TTS conditions and evaluate the influence of children language skills on their performance. We predict that children will have greater phonological precision of the novel words in quiet than in the presence of TTS. We also predict that children’s verbal working memory skills and vocabulary knowledge will relate to greater learning, regardless of listening condition.

Benefits of app-based speech in noise screener for children

Current hearing screening methods focus on assessing a child’s ability to hear tones in quiet. However, this isn’t reflective of real-world classroom situations. Our proposed screening test uses speech in quiet and noise to evaluate a child’s auditory comprehension and possible auditory processing abilities. In this study, we investigate whether a speech in noise screener, Hearing Assessment in Response to Noise Screener (HeARS), is sensitive to detecting possible listening difficulties. We measured responses to a four-choice task with adapting signal to noise ratios based on individual performance. Following an auditory stimulus, the child is presented with four choices that are visual images of the spoken words. The child selects the correct image they hear, and based on their performance the signal to noise ratios increase or decrease in difficulty. Scores are reported as percent correct. We hypothesized that results from the screener would capture differences between speech understanding in noise and quiet conditions. In addition, a speech in noise screener may be more sensitive to deficits in auditory comprehension than traditional screening methods. Preliminary data suggest that the accuracy of understanding words in background noise increases with age. Results have implications for identifying children with auditory comprehension and processing deficits sooner, especially in underserved populations.

Wall-cooling effects on secondary instabilities of Mack mode disturbances at Mach 6

In hypersonic boundary layers, Mack modes play a crucial role in flow instability, whose secondary instability is a hot research topic. Since hypersonic flight vehicles will probably work under high-stagnation temperature conditions, which significantly affect the aerodynamic heating calculation and aero-thermal protection design of hypersonic vehicles, it is necessary to compare the primary and secondary instabilities in high-stagnation temperature boundary layers and that in the Boeing/AFOSR Mach 6 quiet tunnel (BAM6QT). Herein, wall-cooling is adopted in order not to consider chemical reactions. With the same freestream temperature of 100 K, two Mach 6 boundary layers with the wall temperature of 20 and 600 K, corresponding to the cooled wall condition and the quiet wind tunnel condition, respectively, are chosen to conduct the linear/non-linear stability and the secondary instability analysis. Our results show that the most dangerous Mack mode originates from a fast discrete mode in the present cooled-wall flow and the most dangerous Mack mode is born from the slow discrete modes in BAM6QT boundary layers. Furthermore, when the primary amplitude of Mack mode disturbances is large, the fundamental resonance always dominates the secondary instability, resulting in steady streaky structures that have the largest amplitude in the spectrum. In addition, the present results point out that the distribution of the eigenfunctions of the fundamental modes and subharmonic modes are significantly different under various wall-temperatures. What is more, different ratios of wall temperature to incoming flow temperature have changed the spanwise wave-angle of the secondary disturbances.

Re-evaluate the data of English vowel perception in quiet and noise for native and non-native listeners: Sensitivity and response bias

For decades, research on vowel perception has been primarily focused on the percentage correct of identification. Limited studies take listeners’ response bias into consideration and applied signal detection theory (SDT) in the data analysis of vowel identification. The goal of this study was to investigate English vowel identification in quiet, long-term speech-shaped noise (LTSS), and multi-talker babble (MTB) for English-native (EN), Chinese-native in the US (CNU), and Chinese-native in China (CNC) listeners by computing their sensitivity (measured by d’) and response bias (measured by c) using the SDT. Results showed that (1) in all three listening conditions, EN listeners showed higher sensitivity and lower bias than CNU and CNC listeners; (2) in quiet and MTB, CNU group demonstrated higher sensitivity than CNC group with similar sensitivity in LTSSN between two Chinese groups; and (3) in MTB, CNU group had smaller bias than CNC group, while in quiet and LTSSN condition, two Chinese groups showed similar bias. These results suggest that the US residency may not improve Chinese-native listeners’ vowel identification capacity, instead, may shift their response strategy toward native speakers’ pattern. [Work by the University of Texas at Austin Research Grant and China National Natural Science Foundation 31628009.]

Initial Response of Nightside Auroral Currents to a Sudden Commencement: Observations of Electrojet and Substorm Onset

AbstractStorm sudden commencements (SSC) often precede geomagnetic storms. Commonly, it takes some hours from the step‐like change that marks the SSC to the start of the magnetic storm activity. In a subset of cases, however, auroral activity starts almost instantaneously after the SSC. To the authors knowledge, the conditions that enable this rapid activation have not been investigated in detail before. Here we consider all the sudden commencements (SC) during the years 2000–2020. Our focus is on the initial response of the auroral currents on the nightside. For that purpose, we make use of the IMAGE Magnetometer Network in Fennoscandia. In about 30% of SC events an initial activation of the westward electrojet is observed. Magnetic deflections of the northward component, surpassing frequently 1,000 nT, are observed only 4 min after the SC. These intense westward currents, flowing typically in narrow channels of 1°–2° latitudinal width, last some 10 min. The electrojets are conjugate to regions in the magnetosphere near geostationary orbits. In several cases geomagnetic substorm onsets are observed about 30 min after the SC. These start typically at fairly high latitude, around 71° magnetic latitude. This is an indication for rather quiet conditions preceding the onset. The magnetic pulse of the SC seems to play an important role in initiating the strong electrojets and the substorms. These initial activities are of relevance for space weather effects because of their strong and rapid variations. This paper provides detailed observations of the initial auroral activity following some SCs.

Developing a Deep Learning-Based Detector of Magnetic, Ne, Te and TEC Anomalies from Swarm Satellites: The Case of Mw 7.1 2021 Japan Earthquake

Since the appearance and evolution of earthquake ionospheric precursors are expected to show a nonlinear and complex behaviour, the use of nonlinear predictor models seems more appropriate. This paper proposes a new approach based on deep learning as a powerful tool for extracting the nonlinear patterns from a time series of ionospheric precursors. A Long Short-Term Memory (LSTM) network as a type of Recurrent Neural Network (RNN) was used to investigate 52 six-month time series, deduced from the three Swarm satellite (Alpha (A), Bravo (B) and Charlie (C)) measurements, including electron density (Ne), electron temperature (Te), magnetic scalar and vector (X, Y, Z) components, Slant and Vertical Total Electron Content (STEC and VTEC), for day and night periods around the time and location of a seismic event. This new approach was tested on a strong Mw = 7.1 earthquake in Japan on 13 February 2021, at 14:07:50 UTC by comparing the results with two implemented methods, i.e., Median and LSTM methods. Furthermore, clear anomalies are seen by a voting classification method 1, 6, 8, 13, 31 and 32 days before the earthquake. A comparison with atmospheric data investigation is further provided, supporting the lithosphere–atmosphere–ionosphere coupling (LAIC) mechanism as a suitable theory to explain the alteration of upper geolayers in the earthquake preparation phase. In other words, using multi-method and multi-precursor analysis applied to 52 time series and also to the orbit-by-orbit investigation, the observed anomalies on the previous day and up to 32 days before the event in normal solar and quiet geomagnetic conditions could be considered as a striking hint of the forthcoming Japan earthquake.

Effects of an Active Noise Control Technology Applied to Earphones on Preferred Listening Levels in Noisy Environments.

Background and ObjectivesThe harmful effects of frequent exposure to loud sounds through portable music players (PMPs) in combination with earphones have been suggested to result in a high prevalence of recreational noise-induced hearing loss among children, adolescents, and young adults. The present study aimed to evaluate the effects of an active noise control technology applied to earphones on the preferred listening levels (PLLs) while listening to music in the presence of background noise. Subjects and MethodsTwenty-three adults between 20 and 40 years with normal hearing were recruited for this study. PLLs for listening to pop-rock and classical music were measured in the participants’ ear canal with a commercially available PMP for four earphone/headphone configurations in quiet and noisy conditions. Ear canal insertion loss was measured in open ear conditions as well as earphone/headphone conditions. ResultsThe average PLL while using earphones and headphones exceeded 85 dBA corresponding to the sound level to induce hearing damage, but in the case of canal earphones with noise cancelling (NC), it was below 75 dBA, corresponding to potentially harmful levels. The background subway noise significantly increased the PLL measured in quiet conditions using any four earphone/headphone types except canal earphones with NC. Canal earphones with NC showed the lowest PLLs compared with participants’ average PLLs using the other three earphone/headphone types. ConclusionsTo minimize recreational noise exposure at the risk of PMP use, the use of earphones with NC is recommended in noisy environments.

Cortical auditory evoked potentials, brain signal variability and cognition as biomarkers to detect the presence of chronic tinnitus

The current limited understanding of tinnitus neurophysiology is one of the major obstacles in developing effective treatments for chronic tinnitus. As such, there is an urgent need for knowledge on underlying neural and/or neurobehavioral correlates that might function as potential biomarkers for tinnitus. We aimed to develop a model for the detection of tinnitus cases based on such potential biomarkers. In a first step, data from twenty patients suffering from chronic tinnitus, but no concurrent hearing loss or psychological complaints, were compared to data from twenty matched controls. Cortical auditory evoked potentials (CAEP) were elicited using a standard oddball paradigm. Source estimation and brain signal variability were analyzed to investigate putative differences between tinnitus patients and controls. Other examinations included standard audiometry, speech understanding in quiet and noisy conditions, and cognitive testing using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The P300 component, a response to unexpected but relevant stimuli, was significantly reduced in the tinnitus group. Source estimation revealed that the response of tinnitus patients was characterized by a decreased activity in temporal cortex, parahippocampus and insula. Brain signal variability on fine time scales was significantly higher in the tinnitus group, suggesting that tinnitus patients rely more strongly on local information processing. Furthermore, tinnitus was associated with a decreased cognitive performance, especially on tasks measuring delayed memory. In a second step, a logistic regression model was constructed based on CAEP activity, brain signal variability and RBANS scores. This model performed significantly above chance level when detecting tinnitus cases in an unseen dataset (accuracy of 75%, area under the ROC curve of 0.86). The successful classification between tinnitus cases and controls demonstrates the potential value of the proposed combination of biomarkers. Moreover, the identified associations between tinnitus, auditory evoked activity and cognitive performance point towards a significant contribution of top-down information processing in the perception of tinnitus.

The Impact of Acute Tinnitus on Listening Effort: A Study Based on Clinical Observations of Sudden Sensorineural Hearing Loss Patients.

This study investigates the relationship between listening effort and acute tinnitus over the clinical course of sudden sensorineural hearing loss (SSNHL) before and after treatment. Thirty SSNHL patients with acute tinnitus were enrolled in this prospective study. Each patient was evaluated before treatment and after 1 and 3 months of follow-up. Listening effort was evaluated in the unaffected ears in two conditions (with and without background noise) using a dual-task paradigm, which included a primary (speech recognition) task and a secondary (visual reaction time) task. Tinnitus severity was assessed with the Tinnitus Handicap Inventory (THI). It was observed that background noise significantly increased listening effort in SSNHL patients with acute tinnitus before and after treatment. THI scores and listening effort in quiet conditions (** p = 0.009) were significantly decreased three months after treatment. In an analysis of the relation between tinnitus severity and listening effort, it was found that the THI total score was significantly correlated with listening effort in quiet (* p = 0.0388) and noisy conditions (* p = 0.044) before treatment. We concluded that SSNHL patients with acute tinnitus exerted greater listening effort in the presence of background noise than in quiet conditions. Furthermore, listening effort was reduced as tinnitus improved in SSNHL patients during the three months after treatment. Both before and after 3 months of treatment, patients who were more affected and emotionally distressed by tinnitus tended to exert more listening effort in both quiet and noisy environments.

Equatorward Medium to Large‐Scale Traveling Ionospheric Disturbances of High Latitude Origin During Quiet Conditions

AbstractThis article presents observations of medium to large‐scale traveling ionospheric disturbances (TIDs) originating from high latitudes, and propagating across the equator into the opposite hemisphere in the African‐European sector during geomagnetically quiet conditions between 2010 and 2018. During the study period, four geomagnetically quiet days were selected each month. The Global Navigation Satellite Systems (GNSS) total electron content (TEC) data were used to obtain the two dimensional (2‐D) TEC residuals. We have identified seven transhemispheric TIDs from the days that were analyzed with five originating in the southern and the rest in northern wintertime hemisphere. The TIDs meridional propagation velocities, periods and wavelengths are in the range of 270–322 m/s, 48–80 min and 802–1,296 km, respectively. The horizontal propagation velocities and horizontal wavelengths ranges are cH = 120–274 m/s and λH = 379–1,104 km, respectively. Analysis of the conditions of the space weather environment rules out space weather as a source of the TIDs. While observations of the 4.3 μm brightness temperature (BT) from the Atmospheric Infrared Sounder (AIRS) instrument on board the NASA Aqua satellite show the existence of atmospheric gravity waves (AGWs) in the troposphere‐stratosphere region, it is suggested that the tertiary GWs from orographic forcing may be the likely source of the TIDs observed in this study.

CCi-MOBILE: A Portable Real Time Speech Processing Platform for Cochlear Implant and Hearing Research.

Experimental hardware-research interfaces form a crucial role during developmental stages of any medical, signal-monitoring system as it allows researchers to test and optimize output results before perfecting the design for the actual FDA approved medical device and large-scale production. These testing platforms, intake raw signals through which performance of novel algorithms can be analyzed and modified to generate the desired data points for an optimized output, allowing the advancement of the medical device. With cochlear implants (CIs) and hearing aids (HAs) becoming a more common solution for varying degrees of hearing impairment, having modern signal processing strategies tested for such speech sensitive systems is a necessity. But the rigid design requirements of commercial CI and HA processors make it difficult to explore novel algorithms for research investigations and conducting longitudinal studies. This study presents the design, development, clinical evaluation, and applications of CCi-MOBILE, a computationally powerful signal processing testing platform built for researchers in the hearing-impaired field. The custom-made, portable research platform allows researchers to design and perform complex speech processing algorithm assessment offline and in real-time. It can be operated through user-friendly, open-source software and is compatible with implants manufactured by Cochlear Corporation. The FPGA design and hardware processing pipeline for CI stimulation is discussed followed by results from an acute study with implant users' speech intelligibility in quiet and noisy conditions. The results show a consistent level of performance compared with CI users' clinical processor, thus confirming the viability of the platform in chronic CI based studies.

Euler Potentials for Dungey Magnetosphere With Axisymmetric Ring and Field‐Aligned Currents

AbstractEuler potentials are found for the magnetic field in the inner magnetosphere, consisting of the Earth's dipole field, the Dungey term, ring current (RC), and field‐aligned current (FAC). The magnetic field in this approximation is axially symmetric. One Euler potential for the dipole, Dungey term, and RC is the same, while that for the magnetic field induced by FAC is different and calculated in this work under the condition that all four field contributions have the same second Euler potential. The Euler potentials are determined for quiet, severe, and superstorm geomagnetic conditions. The restriction of the model is its axial symmetry, so changes of the location and intensity of the currents with azimuthal angle are not explicitly present. On the other hand, these parameters can be changed in the model, and one can study local distributions.

Determination of 3D near fault seismic behaviour of Oroville earth fill dam using burger material model and free field-quiet boundary conditions

ABSTRACT In this study, the three-dimensional (3D) near-fault earthquake performance of the Oroville dam is examined considering a special material model and various seismic boundary conditions. The 3D finite-difference model of the Oroville EF dam is modeled using the finite difference method. Burger Creep (BC) material model is utilized for the foundation and dam body materials. Special interface elements are taken into account between the dam body and foundation. Fix, free field, and quiet seismic boundary conditions are considered for 3D nonlinear earthquake analyses. Total six various strong near-fault earthquakes are used in the 3D analyses. According to the non-linear earthquake analyses, principal stresses, horizontal and vertical displacements for three nodal points are assessed in detail and numerical results are compared for reflecting and non-reflecting seismic boundary conditions. It is clearly understood that seismic boundary conditions should not be utilized randomly for 3D modeling and analysis of EF dams.