Robin Scheibler

Raking the Cocktail Party

We present the concept of an acoustic rake receiver-a microphone beamformer that uses echoes to improve the noise and interference suppression. The rake idea is well-known in wireless communications; it involves constructively combining different multipath components that arrive at the receiver antennas. Unlike spread-spectrum signals used in wireless communications, speech signals are not orthogonal to their shifts. Therefore, we focus on the spatial structure, rather than the temporal. Instead of explicitly estimating the channel, we create correspondences between early echoes in time and image sources in space. These multiple sources of the desired and the interfering signal offer additional spatial diversity that we can exploit in the beamformer design. We present several “intuitive” and optimal formulations of acoustic rake receivers, and show theoretically and numerically that the rake formulation of the maximum signal-to-interference-and-noise ratio beamformer offers significant performance boosts in terms of noise and interference suppression. Beyond signal-to-noise ratio, we observe gains in terms of the perceptual evaluation of speech quality (PESQ) metric for the speech quality. We accompany the paper by the complete simulation and processing chain written in Python. The code and the sound samples are available online at http://lcav.github.io/AcousticRake Receiver/.

The Fukushima inverse problem

Knowing what amount of radioactive material was released from Fukushima in March 2011 is crucial to understand the scope of the consequences. Moreover, it could be used in forward simulations to obtain accurate maps of deposition. But these data are often not publicly available, or are of questionable quality. We propose to estimate the emission waveforms by solving an inverse problem. Previous approaches rely on a detailed expert guess of how the releases appeared, and they produce a solution strongly biased by this guess. If we plant a nonexistent peak in the guess, the solution also exhibits a nonexistent peak. We propose a method based on sparse regularization that solves the Fukushima inverse problem blindly. Together with the atmospheric dispersion models and worldwide radioactivity measurements our method correctly reconstructs the times of major events during the accident, and gives plausible estimates of the released quantities of Xenon.

A Fast Hadamard Transform for Signals With Sublinear Sparsity in the Transform Domain

In this paper, we design a new iterative low-complexity algorithm for computing the Walsh–Hadamard transform (WHT) of an

A fast Hadamard transform for signals with sub-linear sparsity

N

Raking echoes in the time domain

dimensional signal with a

FRIDA: FRI-based DOA estimation for arbitrary array layouts

K

Hardware and software for reproducible research in audio array signal processing

-sparse WHT. We suppose that

The recursive hessian sketch for adaptive filtering

N

Fast continuous Fourier and Haar transforms of rectilinear polygons from very-large-scale integration layouts

is a power of two and

Computing exact Fourier series coefficients of IC rectilinear polygons from low-resolution fast Fourier coefficients

K=O(N^\alpha)