Raking echoes in the time domain

Abstract

The geometry of room acoustics is such that the reverberant signal can be seen as the same waveform emitted from multiple locations. In analogy with the rake receiver from wireless com munications, we propose several beamforming strategies that exploit, rather than suppress, this additional spatio-temporal di versity. Unlike earlier work in the frequency domain, time do main designs allow to shape the impulse response of the beam former. In particular, we can control perceptually relevant pa rameters, such as the amount of early echoes or the length of the beamformer response.Relying on the knowledge of the image sources positions, we derive different optimal beamformers. Leveraging percep tual cues, we show how to improve interference and noise re duction without degrading the perceptual quality. The designs are validated through simulation. Using early echoes is shown to strictly improve the signal to interference and noise ratio. Code and speech samples are available online at http: / / lcav.epfl.ch/Robin_Scheibler.

dEchorate: a calibrated room impulse response dataset for echo-aware signal processing

“…Recently, these methods have been used for noise and interferer suppression in [16,65] and for noise and reverberation reduction in [17,66]. The main limitation of these explicit echo-aware works is that echo properties, or alternatively the position of image sources, must be known or estimated a priori.…”

Raking the Cocktail Party

“…Another line of ongoing work investigates the time-domain formulations of the ARRs, with some initial results already available [25]. Time-domain formulations offer better control over whether the echoes appear before or after the direct sound.…”

“…Timedomain designs [24] offer better control over the impulse responses of the beamforming filters, but they are out of the scope of this paper. For a recent time-domain approach to ARR, see [25].…”

dEchorate: a Calibrated Room Impulse Response Database for Echo-aware Signal Processing

“…. , R − 1 denotes the reflection order, Recently, these methods have been used for noise and interferer suppression in [9,57] and for noise and reverberation reduction in [10,58]. The main limitation of these works is that echo properties, or alternatively the position of image sources, must be known a priori.…”