| 1. |
- Bayley, Todd, et al.
(författare)
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Call Quality Monitoring for VoIP
- 2011
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Konferensbidrag (refereegranskat)abstract
- A method of monitoring the speech quality of a Voice-over-IP call is described in this paper. This method is attractive because it employs the ITU-T standard P.862 for Perceptual Evaluation of Speech Quality which is well-known for its accuracy. In addition, with the proposed method, call quality is monitored without interfering with the call while it is in progress. The results corresponding to an implementation of this method shows call quality can be measured with excellent accuracy under typical network delays.
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| 2. |
- Björklund, Anna, et al.
(författare)
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Energiplanering med strategisk miljöbedömning i Finspång
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport är en del av slutrapporteringen från två av projekten i programmet ”Miljöstrategiska verktyg”. Projekten är Utveckling av verktyg för strategisk miljöbedömning och medborgarmedverkan (MiSt-projekt 1) samt Scenariometoder i strategisk miljöbedömning (MiSt-projekt 7). I samarbete med Finspångs kommun har ett gemensamt projekt utvecklats för att ta fram en ny energiplan i kommunen. Programmet "Miljöstrategiska verktyg", MiSt, är ett tvärvetenskapligt forskningsprogram finansierat av Naturvårdsverket. Programmet leds från Blekinge Tekniska Högskola. I programmet studeras verktyg som kan underlätta miljöbedömning i strategiskt beslutsfattande på olika nivåer, från nationell till lokal. Förståelsen och basen för utveckling av verktyg och rekommendationer om verktyg i olika planerings- och beslutsprocesser baseras på empirisk forskning på fall inom flera sektorer. Målen för MiSt-programmet: • Kritisk undersökning av verktygens funktion • Teoribaserad förståelse av deras verkan • Utveckling av råd om effektiv användning av verktyg och kombinationer avverktyg
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| 3. |
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| 4. |
- Grbic, Nedelko, et al.
(författare)
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Speech Enhancement for Hands-Free Terminals
- 2001
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 5. |
- Isehed, Catrine, et al.
(författare)
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Effectiveness of enamel matrix derivative on the clinical and microbiological outcomes following surgical regenerative treatment of peri-implantitis : A randomized controlled trial
- 2016
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Ingår i: Journal of Clinical Periodontology. - Hoboken, USA : Wiley-Blackwell Publishing Inc.. - 0303-6979 .- 1600-051X. ; 43:10, s. 863-873
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This randomized clinical trial aimed at comparing radiological, clinical and microbial effects of surgical treatment of peri-implantitis alone or in combination with enamel matrix derivative (EMD).Methods: Twenty-six subjects were treated with open flap debridement and decontamination of the implant surfaces with gauze and saline preceding adjunctive EMD or no EMD. Bone level (BL) change was primary outcome and secondary outcomes were changes in pocket depth (PD), plaque, pus, bleeding and the microbiota of the peri-implant biofilm analyzed by the Human Oral Microbe Identification Microarray over a time period of 12 months.Results: In multivariate modelling, increased marginal BL at implant site was significantly associated with EMD, the number of osseous walls in the peri-implant bone defect and a Gram+/aerobic microbial flora, whereas reduced BL was associated with a Gram-/anaerobic microbial flora and presence of bleeding and pus, with a cross-validated predictive capacity (Q(2) ) of 36.4%. Similar, but statistically non-significant, trends were seen for BL, PD, plaque, pus and bleeding in univariate analysis.Conclusion: Adjunctive EMD to surgical treatment of peri-implantitis was associated with prevalence of Gram+/aerobic bacteria during the follow-up period and increased marginal BL 12 months after treatment.
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| 6. |
- Johansson, Anders
(författare)
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Acoustic Sound Source Localisation and Tracking : in Indoor Environments
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With advances in micro-electronic complexity and fabrication, sophisticated algorithms for source localisation and tracking can now be deployed in cost sensitive appliances for both consumer and commercial markets. As a result, such algorithms are becoming ubiquitous elements of contemporary communication, robotics and surveillance systems. Two of the main requirements of acoustic localisation and tracking algorithms are robustness to acoustic disturbances (to maximise localisation accuracy), and low computational complexity (to minimise power-dissipation and cost of hardware components). The research presented in this thesis covers both advances in robustness and in computational complexity for acoustic source localisation and tracking algorithms. This thesis also presents advances in modelling of sound propagation in indoor environments; a key to the development and evaluation of acoustic localisation and tracking algorithms. As an advance in the field of tracking, this thesis also presents a new method for tracking human speakers in which the problem of the discontinuous nature of human speech is addressed using a new state-space filter based algorithm which incorporates a voice activity detector. The algorithm is shown to achieve superior tracking performance compared to traditional approaches. Furthermore, the algorithm is implemented in a real-time system using a method which yields a low computational complexity. Additionally, a new method is presented for optimising the parameters for the dynamics model used in a state-space filter. The method features an evolution strategy optimisation algorithm to identify the optimum dynamics’ model parameters. Results show that the algorithm is capable of real-time online identification of optimum parameters for different types of dynamics models without access to ground-truth data. Finally, two new localisation algorithms are developed and compared to older well established methods. In this context an analytic analysis of noise and room reverberation is conducted, considering its influence on the performance of localisation algorithms. The algorithms are implemented in a real-time system and are evaluated with respect to robustness and computational complexity. Results show that the new algorithms outperform their older counterparts, both with regards to computational complexity, and robustness to reverberation and background noise. The field of acoustic modelling is advanced in a new method for predicting the energy decay in impulse responses simulated using the image source method. The new method is applied to the problem of designing synthetic rooms with a defined reverberation time, and is compared to several well established methods for reverberation time prediction. This comparison reveals that the new method is the most accurate.
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| 7. |
- Johansson, Anders, et al.
(författare)
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Speaker localisation using the far-field SRP-PHAT in conference telephony
- 2002
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Konferensbidrag (refereegranskat)abstract
- This paper describes a robust algorithm for sound source localization in conference rooms. The method used is a modi¯ed steered response power phase alignment transform algorithm. The results are obtained by processing real data recorded in a typical conference room, and they are compared to data obtained from a simple free-field model. The algorithm demonstrates good accuracy for ¯nding the correct angle of arrival for the dominant speaker in the room and works well for speech sources. The algorithm integrates well with subband decomposition and is suited for realtime applications.
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| 8. |
- Lagö, Thomas L, et al.
(författare)
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Analysis of Helicopter Sound for the Development of A New Generation Active Headset
- 1997
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Konferensbidrag (refereegranskat)abstract
- Helicopters generate substantial noise levels, especially at low frequency. These noise levels are normally not harmful for the ear. However, the low frequency content masks the speech. Therefore, pilots tend to set the communication system at maximum level so that the sound levels reach severe amplitudes for the ear. These high sound levels are exposing the ear to fatigue and hearing loss. The low speech intelligibility caused by the background noise is also a safety issue since it is most important that all commands can be understood correctly. The risk of noise induced hearing loss can normally be evaluated by sound pressure level measurements. However, in some cases, the standardized methods for these measurements does not take into account some secondary effects of the frequency distribution of the sound pressure levels. This paper addresses a noise exposure situation where the noise level itself is not harmful for hearing but is still the reason for increased risk for noise induced hearing loss. Military helicopter crews in Sweden have recent shown an increase in noise induced hearing loss. A combined active passive technique has been chosen as a possible solution. Therefore, the dominant sound sources have to be identified and the number of harmonics for each source determined. An investigation of the coupling between the structure borne sound and the air borne sound was also performed. This analysis is the basis for the development of a new generation active headset, and is presented in this paper.
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