Multichannel Online Blind Speech Dereverberation with Marginalization of Static Observation Parameters in a Rao-Blackwellized Particle Filter

Room reverberation leads to reduced intelligibility of audio signals and spectral coloration of audio signals. Enhancement of acoustic signals is thus crucial for high-quality audio and scene analysis applications. Multiple sensors can be used to exploit statistical evidence from multiple observations of the same event to improve enhancement. Whilst traditional beamforming techniques suffer from interfering reverberant reflections with the beam path, other approaches to dereverberation often require at least partial knowledge of the room impulse response which is not available in practice, or rely on inverse filtering of a channel estimate to obtain a clean speech estimate, resulting in difficulties with non-minimum phase acoustic impulse responses. This paper proposes a multi-sensor approach to blind dereverberation in which both the source signal and acoustic channel are directly estimated from the distorted observations using their optimal estimators. The remaining model parameters are sampled from hypothesis distributions using a particle filter, thus facilitating real-time dereverberation. This approach was previously successfully applied to single-sensor blind dereverberation. In this paper, the single-channel approach is extended to multiple sensors. Performance improvements due to the use of multiple sensors are demonstrated on synthetic and baseband speech examples

Partial equalization of non-minimum-phase impulse responses

<p/> <p>We propose a modified version of the standard homomorphic method to design a minimum-phase inverse filter for non-minimum-phase impulse responses equalization. In the proposed approach some of the dominant poles of the filter transfer function are replaced by new ones before carrying out the inverse DFT. This method is useful when partial magnitude equalization is intended. Results for an impulse response measured in the car interior show that by using the modified version we can control the sound quality more precisely than when using the standard method.</p

U.S. policy in the UN environmental arena: powerful laggard or constructive leader?

Environment, Sustainable development, United Nations, United States,

The mid-term clinical results of the phase 3 Oxford unicompartmental knee arthroplasty: a 6- to 8-year follow-up

Unicompartmental knee arthroplasty (UKA) is widely performed in the United Kingdom for the management of patients with symptomatic osteoarthritis of the medial compartment of the tibiofemoral joint. A limited number of papers have presented the findings of mid-term clinical and survival data with sufficiently large patient numbers following mobile-bearing UKA. The purpose of this study was to present the 6- to 8-year follow-up data on a series of 230 minimally invasive medial Oxford Phase 3 mobile-bearing UKAs in our institution. Data on surgical procedure, postoperative rehabilitation requirement, complications, revision procedures and Oxford Knee Score (OKS), Short Form-12 (SF-12) and visual analogue scale (VAS) pain scores were analysed. The results indicated that the majority of patient’s recoveries were uneventful, with 96% experiencing no postoperative complications. The mean OKS, VAS pain and SF-12 scores indicated good functional outcomes and acceptable perceived general health for this age group. Twenty-one patients underwent revision surgery, indicating a survival rate of 85% (95% CI: 0.76–0.91) during the 6- to 8-year follow-up period. The most frequently cited indication for revision was due to progression of osteoarthritis to the lateral component. To conclude, this series indicated that the mobile-bearing Oxford UKA provides good clinical outcomes at 6- to 8-year follow-up, with minimal requirement for postoperative rehabilitation, few complications and an acceptable survivorship in the mid-term