Secure Audio-Visual Data Exchange for Android In-Vehicle Ecosystems

Mobile device pairing inside vehicles is a ubiquitous task which requires easy to use and secure solutions. In this work we exploit the audio-video domain for pairing devices inside vehicles. In principle, we rely on the widely used elliptical curve version of the Diffie-Hellman key-exchange protocol and extract the session keys from the acoustic domain as well as from the visual domain by using the head unit display. The need for merging the audio-visual domains first stems from the fact that in-vehicle head units generally do not have a camera so they cannot use visual data from smartphones, however, they are equipped with microphones and can use them to collect audio data. Acoustic channels are less reliable as they are more prone to errors due to environmental noise. However, this noise can be also exploited in a positive way to extract secure seeds from the environment and audio channels are harder to intercept from the outside. On the other hand, visual channels are more reliable but can be more easily spotted by outsiders, so they are more vulnerable for security applications. Fortunately, mixing these two types of channels results in a solution that is both more reliable and secure for performing a key exchange.

Reading fluency and statistical learning across modalities and domains: online and offline measures

The vulnerability of statistical learning has been demonstrated in reading difficulties in both the visual and acoustic domains. We examined segmentation abilities of adolescents with three different levels of reading fluency in the acoustic verbal and visual nonverbal domains. We applied online target detection tasks, where the extent of learning is reflected in differences between reaction times to predictable versus unpredictable targets. Explicit judgments of well-formedness were also elicited in an offline two-alternative forced choice task. A significant online learning effect was observed in all groups in both domains, and online patterns were similar in participants with low, medium and high reading fluency. On the offline measures, all groups were at chance in the visual, but not the verbal domain. These findings suggest that there is no robust statistical learning impairment associated with reading problems either in the visual or the acoustic domain in adolescents. Results also imply that offline measures may mask learning abilities, and measuring learning online can provide a deeper understanding of the learning process and of its potential deficits.

A Time-Shifting Algorithm for Alleviating Convergence Difficulties at Interior Acoustic Resonance Frequencies

This paper proposes a time-shifting boundary element method in the time domain to calculate the radiating pressures of an arbitrary object pulsating at eigenfrequencies of the interior (i.e., interior resonance frequencies). In this paper, the frequency shifting is time-step-dependent and could be viewed as an iterative, or relaxation, technique for the solution of the problem. The proposed method avoids numerical problems due to the internal resonance frequency by initializing the iteration with each scaled frequency. The scaled frequency is approximately equal to the true frequency at the last iterating time step. A sphere pulsating at the eigenfrequency in an infinite acoustic domain was calculated first; the result was compared with the analytical solution, and they were in good agreement. Moreover, two arbitrary-shaped radiators were taken as study cases to predict the radiating pressures at the interior resonance frequencies, and robustly convergent results were obtained. Finally, the accuracy of the proposed method was tested using a problem with a known solution. A point source was placed inside the object to compute the surface velocities; the computed surface pressures were identical to the pressures computed using the point source.

Effects of concentrated elements on vibro-acoustic characteristics of a circular ring considering both external and internal fluids

This study focuses on the vibro-acoustic characteristics of submerged structures with concentrated elements and filled with fluid. A weak formulation is developed based on the modified variational principle. The accurate energy expressions for both structural and acoustic domains are incorporated into the coupled vibro-acoustic model. With introduced Lagrangian multipliers, a domain partitioning technique is developed to divide the whole acoustic domain into several subdomains. The continuity conditions between adjacent subdomains are further guaranteed by the least square weighted residual method working on the common interfaces. To satisfy the Sommerfeld radiation condition, an artificial boundary with the local absorbing boundary condition is adopted to truncate the infinite external acoustic domain. A water-submerged and air-filled bidimensional circular ring with concentrated elements is used as the research object to validate the accuracy of the proposed approach. The concentrated elements are considered as lumped masses with elastic boundary conditions. The structural displacements and acoustic pressures are expanded by the Fourier series and Chebyshev orthogonal polynomials. Furthermore, the effects of the concentrated elements on the coupled vibro-acoustic responses are carefully investigated, as considering different distribution patterns.

Analysis and Application of Screens for Acoustic Impedance in a Speaker Box with a Passive Radiator to Decrease Standing-Wave Influence

Micro speakers are playing an increasingly important role with the development of multimedia devices. This study applies the lumped-parameter method, which uses an equivalent circuit to model the electromagnetic and mechanical domains. The acoustic domain is modeled using the finite element method. Based on the analysis tool, the use of a screen is analyzed, and the screen is designed to depress the acoustic resonance in the sound-pressure-level curve and improve the performance. The samples are fabricated, and the experiment verifies the analysis method. The experimental result shows that the peak and dip due to the standing wave are cancelled, and the frequency response is smooth when the screen is used.