Evaluation of Ambisonics Decoding Methods with Experimental Measurements

Ambisonics is a sound reproduction technique based on the decomposition of the sound field using spherical harmonics. The truncation in the number of coefficients used to recreate the sound field leads to reproduction artifacts which depend on the frequency and the listener spatial location. In this work, the performance of three different decoding methods (Basic, Max-rE and In-Phase) has been studied and evaluated in the light of the results of experimental measurements. The latter were performed using a spherical array composed of 40 uniformly distributed loudspeakers and a translating 29-channel linear microphone array. An error analysis is presented based on the difference between the desired and synthesized sound pressure and acoustic intensity field. The results indicate that, as expected, the size of the region of accurate sound field reconstruction reduces as frequency increases, but with different trends depending on the type of decoder implemented

Basic Parameter Estimation of Binary Neutron Star Systems by the Advanced LIGO/Virgo Network

Within the next five years, it is expected that the Advanced LIGO/Virgo network will have reached a sensitivity sufficient to enable the routine detection of gravitational waves. Beyond the initial detection, the scientific promise of these instruments relies on the effectiveness of our physical parameter estimation capabilities. The majority of this effort has been towards the detection and characterization of gravitational waves from compact binary coalescence, e.g. the coalescence of binary neutron stars. While several previous studies have investigated the accuracy of parameter estimation with advanced detectors, the majority have relied on approximation techniques such as the Fisher Matrix. Here we report the statistical uncertainties that will be achievable for optimal detection candidates (SNR = 20) using the full parameter estimation machinery developed by the LIGO/Virgo Collaboration via Markov-Chain Monte Carlo methods. We find the recovery of the individual masses to be fractionally within 9% (15%) at the 68% (95%) credible intervals for equal-mass systems, and within 1.9% (3.7%) for unequal-mass systems. We also find that the Advanced LIGO/Virgo network will constrain the locations of binary neutron star mergers to a median uncertainty of 5.1 deg^2 (13.5 deg^2) on the sky. This region is improved to 2.3 deg^2 (6 deg^2) with the addition of the proposed LIGO India detector to the network. We also report the average uncertainties on the luminosity distances and orbital inclinations of ideal detection candidates that can be achieved by different network configurations.Comment: Second version: 15 pages, 9 figures, accepted in Ap

Proteasome inhibition by bortezomib parallels a reduction in head and neck cancer cells growth, and an increase in tumor-infiltrating immune cells

Head and neck cancer (HNC) has frequently an aggressive course for the development of resistance to standard chemotherapy. Thus, the use of innovative therapeutic drugs is being assessed. Bortezomib is a proteasome inhibitor with anticancer effects. In vitro antitumoral activity of Bortezomib was investigated employing human tongue (SCC-15, CAL-27), pharynx (FaDu), salivary gland (A-253) cancer cell lines and a murine cell line (SALTO-5) originated from a salivary gland adenocarcinoma arising in BALB-neuT male mice transgenic for the oncogene neu. Bortezomib inhibited cell proliferation, triggered apoptosis, modulated the expression and activation of pro-survival signaling transduction pathways proteins activated by ErbB receptors and inhibited proteasome activity in vitro. Intraperitoneal administration of Bortezomib delayed tumor growth of SALTO-5 cells transplanted in BALB-neuT mice, protracted mice survival and adjusted tumor microenvironment by increasing tumor-infiltrating immune cells (CD4+ and CD8+ T cells, B lymphocytes, macrophages, and Natural Killer cells) and by decreasing vessels density. In addition, Bortezomib modified the expression of proteasome structural subunits in transplanted SALTO-5 cells. Our findings further support the use of Bortezomib for the treatment of HNC and reveal its ineffectiveness in counteracting the activation of deregulated specific signaling pathways in HNC cell lines when resistance to proteasome inhibition is developed

Evaluation of ambisonics decoding methods with experimental measurements

Ambisonics is a sound reproduction technique based on the decomposition of the sound field using spherical harmonics. The truncation in the number of coefficients used to recreate the sound field leads to reproduction artifacts which depend on the frequency and the listener spatial location. In this work, the performance of three different decoding methods (Basic, Max-rE and In-Phase) has been studied and evaluated in the light of the results of experimental measurements. The latter were performed using a spherical array composed of 40 uniformly distributed loudspeakers and a translating 29-channel linear microphone array. An error analysis is presented based on the difference between the desired and synthesized sound pressure and acoustic intensity field. The results indicate that, as expected, the size of the region of accurate sound field reconstruction reduces as frequency increases, but with different trends depending on the type of decoder implemente

Reproduction of the modal response of enclosures by means of interactive auralization

A method to create an interactive auralization of the modal response of a room is presented. The process is based on the numerical estimation of the spatial impulse responses of the enclosure using a combination of the finite element method and geometrical acoustics. The acoustic field is then reconstructed by means of a plane wave expansion, which allows for interactive features such as translation of the sound field. The auralization is presented to the listener using a headphone-based binaural system. Compared to techniques based only on geometrical acoustic predictions, this hybrid methodology produces a more accurate rendering of the acoustic field at low frequencies, thus providing an effective tool to reproduce the modal response of enclosures in real-time

Low Frequency Interactive Auralization Based on a Plane Wave Expansion

This paper addresses the problem of interactive auralization of enclosures based on a finite superposition of plane waves. For this, room acoustic simulations are performed using the Finite Element (FE) method. From the FE solution, a virtual microphone array is created and an inverse method is implemented to estimate the complex amplitudes of the plane waves. The effects of Tikhonov regularization are also considered in the formulation of the inverse problem, which leads to a more efficient solution in terms of the energy used to reconstruct the acoustic field. Based on this sound field representation, translation and rotation operators are derived enabling the listener to move within the enclosure and listen to the changes in the acoustic field. An implementation of an auralization system based on the proposed methodology is presented. The results suggest that the plane wave expansion is a suitable approach to synthesize sound fields. Its advantage lies in the possibility that it offers to implement several sound reproduction techniques for auralization applications. Furthermore, features such as translation and rotation of the acoustic field make it convenient for interactive acoustic renderings

Low frequency interactive auralization based on a plane wave expansion

This paper addresses the problem of interactive auralization of enclosures based on a finite superposition of plane waves. For this, room acoustic simulations are performed using the Finite Element (FE) method. From the FE solution, a virtual microphone array is created and an inverse method is implemented to estimate the complex amplitudes of the plane waves. The effects of Tikhonov regularization are also considered in the formulation of the inverse problem, which leads to a more efficient solution in terms of the energy used to reconstruct the acoustic field. Based on this sound field representation, translation and rotation operators are derived enabling the listener to move within the enclosure and listen to the changes in the acoustic field. An implementation of an auralization system based on the proposed methodology is presented. The results suggest that the plane wave expansion is a suitable approach to synthesize sound fields. Its advantage lies in the possibility that it offers to implement several sound reproduction techniques for auralization applications. Furthermore, features such as translation and rotation of the acoustic field make it convenient for interactive acoustic renderings.<br/

Room acoustic simulations using the finite element method and diffuse absorption coefficients

An alternative approach based on the use of reverberation time measurements to characterize the boundary conditions on Finite Element room acoustic simulations is proposed. The methodology relies on the estimation of the mean absorption of the room using Sabine/Eyring reverberation equations. From this information, diffuse absorption coefficients are calibrated and the specific acoustic impedance of the absorbing surfaces is calculated. The implications of assuming that the specific acoustic impedance is entirely resistive are also considered. An analysis of the accuracy of the proposed approach is presented for a reference case. The results indicate that the suggested methodology leads to a more accurate prediction of the modal behaviour of the enclosures compared to geometrical acoustic simulations. However, the assumption of a purely resistive specific acoustic impedance leads to shift in frequency which can be compensated for by synthesizing complex impedance phases that provides the same diffuse absorption coefficients.</p