Realtime implementation of a particle filter with integrated voice activity detector for acoustic speaker tracking

Abstract-In noisy and reverberant environments, the problem of acoustic source localisation and tracking (ASLT) using an array of microphones presents a number of challenging difficulties. One of the main issues when considering real-world situations involving human speakers is the temporally discontinuous nature of speech signals: the presence of silence gaps in the speech can easily misguide the tracking algorithm, even in practical environments with low to moderate noise and reverberation levels. This work focuses on a realtime implementation of the ASLT algorithm proposed in [1], which circumvents this problem by integrating measurements from a voice activity detector (VAD) within the tracking algorithm framework. The algorithm is here optimized for low computational complexity, and is implemented on a PC based real-time system. The resulting computational load is calculated and is presented along with real measurements of the true execution speed for the considered algorithm implementation. The results show that the algorithm is suitable for implementation in currently existing low-power embedded systems

Exogenous BMP7 in aortae of rats with chronic uremia ameliorates expression of profibrotic genes, but does not reverse established vascular calcification

<div><p>Hyperphosphatemia and vascular calcification are frequent complications of chronic renal failure and bone morphogenetic protein 7 (BMP7) has been shown to protect against development of vascular calcification in uremia. The present investigation examined the potential reversibility of established uremic vascular calcification by treatment of uremic rats with BMP7. A control model of isogenic transplantation of a calcified aorta from uremic rats into healthy littermates examined whether normalization of the uremic environment reversed vascular calcification. Uremia and vascular calcification were induced in rats by 5/6 nephrectomy, high phosphate diet and alfacalcidol treatment. After 14 weeks severe vascular calcification was present and rats were allocated to BMP7, vehicle or aorta transplantation. BMP7 treatment caused a significant decrease of plasma phosphate to 1.56 ± 0.17 mmol/L vs 2.06 ± 0.34 mmol/L in the vehicle group even in the setting of uremia and high phosphate diet. Uremia and alfacalcidol resulted in an increase in aortic expression of genes related to fibrosis, osteogenic transformation and extracellular matrix calcification, and the BMP7 treatment resulted in a decrease in the expression of profibrotic genes. The total Ca-content of the aorta was however unchanged both in the abdominal aorta: 1.9 ± 0.6 μg/mg tissue in the vehicle group vs 2.2 ± 0.6 μg/mg tissue in the BMP7 group and in the thoracic aorta: 71 ± 27 μg/mg tissue in the vehicle group vs 54 ± 18 μg/mg tissue in the BMP7 group. Likewise, normalization of the uremic environment by aorta transplantation had no effect on the Ca-content of the calcified aorta: 16.3 ± 0.6 μg/mg tissue pre-transplantation vs 15.9 ± 2.3 μg/mg tissue post-transplantation. Aortic expression of genes directly linked to extracellular matrix calcification was not affected by BMP7 treatment, which hypothetically might explain persistent high Ca-content in established vascular calcification. The present results highlight the importance of preventing the development of vascular calcification in chronic kidney disease. Once established, vascular calcification persists even in the setting when hyperphosphatemia or the uremic milieu is abolished.</p></div

Acoustic direction of arrival estimation, a comparison between Root-MUSIC and SRP-PHAT

ABSTRAC

Speech Enhancement for Hands-Free Terminals

This paper discusses signal processing methods for speech extraction in use with voice communication applications such as personal digital assistants (PDA:s), mobile telephone terminals and personal computers. The user will be distant from the device and thus the speech signal entering the device will be subject to reverberation as well as disturbed by background noise. The proposed structure consists of a microphone array which allows for techniques of directional processing. Thus it will be able to enhance a desired speech source and suppress other speech sources in the background. Three different optimal beamforming methods are considered in a real world car hands-free environment; an optimal near-field array gain optimization procedure, a theoretical diffuse noise field model for a point source and a least squares solution

Talförbättring för handhållna terminaler

This paper discusses signal processing methods for speech extraction in use with voice communication applications such as personal digital assistants (PDA:s), mobile telephone terminals and personal computers. The user will be distant from the device and thus the speech signal entering the device will be subject to reverberation as well as disturbed by background noise. The proposed structure consists of a microphone array which allows for techniques of directional processing. Thus it will be able to enhance a desired speech source and suppress other speech sources in the background. Three different optimal beamforming methods are considered in a real world car hands-free environment; an optimal near-field array gain optimization procedure, a theoretical diffuse noise field model for a point source and a least squares solution.Arbetet beskriver problemformuleringen av spatiell talf;rb&apos;ttring av bredbandiga signaler i närfältet. En ny praktisk implementering presenteras och utvärderas

Talförbättring för handhållna terminaler

This paper discusses signal processing methods for speech extraction in use with voice communication applications such as personal digital assistants (PDA:s), mobile telephone terminals and personal computers. The user will be distant from the device and thus the speech signal entering the device will be subject to reverberation as well as disturbed by background noise. The proposed structure consists of a microphone array which allows for techniques of directional processing. Thus it will be able to enhance a desired speech source and suppress other speech sources in the background. Three different optimal beamforming methods are considered in a real world car hands-free environment; an optimal near-field array gain optimization procedure, a theoretical diffuse noise field model for a point source and a least squares solution.Arbetet beskriver problemformuleringen av spatiell talf;rb&apos;ttring av bredbandiga signaler i närfältet. En ny praktisk implementering presenteras och utvärderas

Sense-making of autonomy and control : Comparing school leaders in public and independent schools in a Swedish case

This article analyses how school leaders depict their autonomy and how they make sense of the relationship between autonomy and control. Attention is drawn to three leadership focuses: the pedagogical direction of the school, decision-making over the internal organisation, and school improvement work. The article integrates survey data on Swedish school leaders (n = 1286). In addition, two theoretical categories were applied in the qualitative data analysis to explore how school leaders and local education authorities and its independent counterpart make sense of the relationship between autonomy and control: technical sense-making (TSM) and critical reflective learning. The findings showed that school leaders, both in public and independent schools, experienced a rather high degree of autonomy within the three focuses. The findings also indicated that school leaders in independent schools experienced a higher degree of autonomy regarding the pedagogical direction of the school and school improvement work. However, the effect sizes were low, indicating that the results must be considered with caution. The qualitative data analysis, in turn, revealed an overall emphasis on TSM among school leaders both in public and independent schools, reducing the possibilities for a novel and vibrant leadership. Based on these results, the article concludes that autonomy could constitute an important prerequisite for school leadership, but making sense of the relationship between autonomy and control stands out as even more important for successful school improvement