427 research outputs found
Reconstructing the Dynamic Directivity of Unconstrained Speech
This article presents a method for estimating and reconstructing the spatial
energy distribution pattern of natural speech, which is crucial for achieving
realistic vocal presence in virtual communication settings. The method
comprises two stages. First, recordings of speech captured by a real, static
microphone array are used to create an egocentric virtual array that tracks the
movement of the speaker over time. This virtual array is used to measure and
encode the high-resolution directivity pattern of the speech signal as it
evolves dynamically with natural speech and movement. In the second stage, the
encoded directivity representation is utilized to train a machine learning
model that can estimate the full, dynamic directivity pattern given a limited
set of speech signals, such as those recorded using the microphones on a
head-mounted display. Our results show that neural networks can accurately
estimate the full directivity pattern of natural, unconstrained speech from
limited information. The proposed method for estimating and reconstructing the
spatial energy distribution pattern of natural speech, along with the
evaluation of various machine learning models and training paradigms, provides
an important contribution to the development of realistic vocal presence in
virtual communication settings.Comment: In proceedings of I3DA 2023 - The 2023 International Conference on
Immersive and 3D Audio. DOI coming soo
Injected and Delivered: Fabricating Implicit Control over Actuation Systems by Spoofing Inertial Sensors
Inertial sensors provide crucial feedback for control systems to determine
motional status and make timely, automated decisions. Prior efforts tried to
control the output of inertial sensors with acoustic signals. However, their
approaches did not consider sample rate drifts in analog-to-digital converters
as well as many other realistic factors. As a result, few attacks demonstrated
effective control over inertial sensors embedded in real systems.
This work studies the out-of-band signal injection methods to deliver
adversarial control to embedded MEMS inertial sensors and evaluates consequent
vulnerabilities exposed in control systems relying on them. Acoustic signals
injected into inertial sensors are out-of-band analog signals. Consequently,
slight sample rate drifts could be amplified and cause deviations in the
frequency of digital signals. Such deviations result in fluctuating sensor
output; nevertheless, we characterize two methods to control the output:
digital amplitude adjusting and phase pacing. Based on our analysis, we devise
non-invasive attacks to manipulate the sensor output as well as the derived
inertial information to deceive control systems. We test 25 devices equipped
with MEMS inertial sensors and find that 17 of them could be implicitly
controlled by our attacks. Furthermore, we investigate the generalizability of
our methods and show the possibility to manipulate the digital output through
signals with relatively low frequencies in the sensing channel.Comment: Original publication in the proceedings of the 27th USENIX Security
Symposium, 201
A comparison of voice and gesture across the first two years of life
This dissertation compared gestural and vocal communication in the development of language in early infancy/childhood. The work also has implications regarding the evolution of language. Since language is primarily vocal it might be assumed vocalization is the predominant communication in infancy and that the evolution of language also depended primarily on the evolution of vocal capabilities. But the primary literature actually favors primarily gestural language origins. The present work contradicts the primary literature. Study 1 examined rates of gesture and speech-like vocalizations, or “protophones”, in the first year of life. Infant protophones occurred more than 5 times more often than gestures. Gaze direction toward a possible receiver was rare for both vocalization and gesture, but vocalizations occurred more frequently with directed gaze than gestures. The results thus contradict the widespread belief that early language is founded primarily in gesture, and the gaze directivity data add to the contradiction. Gesture is useless as communication if no one is looking. Yet vocalization, which can communicate without listeners watching, was significantly more often accompanied by gaze directed to caregivers than gesture was. It appeared, therefore, that a greater proportion of vocalizations than gestures in the first year may have been intended as communications. Study 2 evaluated how often children produced gestures and vocalizations (i.e., protophones and words) in the second year of life (at 13, 16 and 20 months). As with Study 1, the results suggested vocalization played a much more important role in language learning than gesture. Gestural activity occurred much more often in the second year than in the first, but vocalization still exceeded gestural acts by more than a factor of two. More importantly, the vast majority of gestures were confined to Universal acts that are not symbolic, but rather constitute deictic indicators (pointing and reaching) that can serve no other communicative functions. In contrast, words or signs can reference abstract categories and can serve a vast array of communicative functions. Words, however, outnumbered signs by a factor greater than 11 across the data at all ages and by a factor of 21 at 20 months
Sound and noise
Sound and noise problems in space environment and human tolerance criteria at varying frequencies and intensitie
Ultra-high-speed imaging of bubbles interacting with cells and tissue
Ultrasound contrast microbubbles are exploited in molecular imaging, where bubbles are directed to target cells and where their high-scattering cross section to ultrasound allows for the detection of pathologies at a molecular level. In therapeutic applications vibrating bubbles close to cells may alter the permeability of cell membranes, and these systems are therefore highly interesting for drug and gene delivery applications using ultrasound. In a more extreme regime bubbles are driven through shock waves to sonoporate or kill cells through intense stresses or jets following inertial bubble collapse. Here, we elucidate some of the underlying mechanisms using the 25-Mfps camera Brandaris128, resolving the bubble dynamics and its interactions with cells. We quantify acoustic microstreaming around oscillating bubbles close to rigid walls and evaluate the shear stresses on nonadherent cells. In a study on the fluid dynamical interaction of cavitation bubbles with adherent cells, we find that the nonspherical collapse of bubbles is responsible for cell detachment. We also visualized the dynamics of vibrating microbubbles in contact with endothelial cells followed by fluorescent imaging of the transport of propidium iodide, used as a membrane integrity probe, into these cells showing a direct correlation between cell deformation and cell membrane permeability
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