2014
Authors
Freitas, SV; Pestana, PM; Almeida, V; Ferreira, A;
Publication
JOURNAL OF VOICE
Abstract
Objectives/Hypothesis. The aim of this article was to describe the results of an audio-perceptual evaluation carried out by 10 judges, on a database comprising 90 voice recordings plus 10 samples repetition, with the purpose of characterizing the intra-and interrater reliability. Study Design. Exploratory, transversal. Methods. The classification of the GRBAS parameters was obtained for each one of the 10 experts, concerning the 90 voice samples. The intraclass correlation coefficient determined the interrater reliability. For the 10 repeated voices, the intrarater reliability was assessed by means of a dispersion analysis. Results. The average judges' classification for each of the GRBAS parameters differs (P < 0.05). The values of the correlations, with confidence intervals of 95%, between the average scores for all components of the GRBAS scale lie, in general, between 0.838 and 0.966. The first three parameters of the scale (G, R, and B) have the higher interrater reliability. Differences were statistically significant (P < 0.05) for experts 1, 6, 9, and 10, which means a poor intrarater reliability for 40% of the judges. Conclusions. All the experts had similar evaluation criteria for the assessment of the five parameters of the GRBAS scale (the values of the confidence intervals at 95% of the experts average ratings of the GRB were above 0.8). However, its quantification is not statistically similar. Asthenia and Strain have lower reliability. Most experts do not reveal statistically significant differences between the values assigned to the GRB parameters (P > 0.05).
2014
Authors
Sousa, R; Ferreira, A; Alku, P;
Publication
BIOMEDICAL SIGNAL PROCESSING AND CONTROL
Abstract
This paper presents an algorithm, in the context of speech analysis and pathologic/dysphonic voices evaluation, which splits the signal of the glottal excitation into harmonic and noise components. The algorithm uses a harmonic and noise splitter and a glottal inverse filtering. The combination of these two functionalities leads to an improved estimation of the glottal excitation and its components. The results demonstrate this improvement of estimates of the glottal excitation in comparison to a known inverse filtering method (IAIF). These results comprise performance tests with synthetic voices and application to natural voices that show the waveforms of harmonic and noise components of the glottal excitation. This enhances the glottal information retrieval such as waveform patterns with physiological meaning.
2014
Authors
Ferreira, A;
Publication
2014 IEEE INTERNATIONAL SYMPOSIUM ON SIGNAL PROCESSING AND INFORMATION TECHNOLOGY (ISSPIT)
Abstract
Normalized Relative Delay (NRD) is a phase-related feature that can be extracted from the harmonic structure of a periodic sound, using accurate frequency and phase estimation. We present research results showing that NRD coefficients reflect the phase structure of glottal pulses and possess a speaker discrimination capability. We use both synthetic and natural voiced vowels uttered by children, adult males and females, to illustrate both the shift-invariance property of NRDs, as well as their speaker discrimination potential, using a Fisher related criterion of data scattering.
2014
Authors
Conceição, S; Ribeiro, F; Campos, R; Ricardo, M;
Publication
2014 IFIP Wireless Days, WD 2014, Rio de Janeiro, Brazil, November 12-14, 2014
Abstract
Wireless Underground Networks (WUNs) include communications links between buried nodes and between buried and aboveground nodes. WUNs have many applications, such as border surveillance, agriculture monitoring, and infrastructure monitoring. Recent studies have shown that they are feasible and have deployment advantages over wired networks. Yet, so far WUNs evaluations have been done using testbeds only, and a tool enabling simulations on TCP/IP WUNs is lacking. We propose a simulator of TCP/IP wireless underground networks based on ns-3. The simulator was validated against experimental results for 433 MHz and 2.4 GHz frequency bands. The results show its accuracy for most of the communications scenarios. © 2014 IEEE.
2014
Authors
Abreu, C; Ricardo, M; Mendes, PM;
Publication
JOURNAL OF NETWORK AND COMPUTER APPLICATIONS
Abstract
Available wireless sensor networks targeting the domain of healthcare enables the development of new applications and services in the context of E-Health. Such networks play an important role in several scenarios of patient monitoring, particularly those where data collection is vital for diagnosis and/or research purposes. However, despite emerging solutions, wearable sensors still depend on users' acceptance. One proposed solution to improve wearability relies on the use of smaller sensing nodes, requiring more energy-efficient networks, due to smaller room available for energy sources. In such context, smaller wireless sensor network nodes are required to work long time periods without human intervention and, at the same time, to provide appropriate levels of reliability and quality of service. Satisfaction of these two goals depends on several key factors, such as the routing protocol, the network topology, and energy efficiency. This paper offers a solution to increase the network lifetime based on a new Energy-Aware Objective Function used to design a Routing Protocol for Low-Power and Lossy Networks. The proposed Objective Function uses the Expected Transmission Count Metric and the Remaining Energy on each sensor node to compute the best paths to route data packets across the network. When compared with state of the art solutions, the proposed method increases the network lifetime by 21% and reduces the peaks of energy consumption by 12%. In this way, wireless sensor network nodes wearability can be improved, making them smaller and lighter, while maintaining the required performance.
2014
Authors
Sousa, F; Campos, R; Ricardo, M;
Publication
IEEE Symposium on Computers and Communications, ISCC 2014, Funchal, Madeira, Portugal, June 23-26, 2014
Abstract
IEEE 802.11-based wireless multimedia sensor networks (WMSN) are a cost-effective and flexible solution for video monitoring scenarios. Yet, they suffer from three major problems: bad performance, throughput unfairness, and energy inefficiency. Several approaches have been considered to tackle these problems but they are too restrictive or complex. In this paper we propose a scheduling approach using FM as a control channel to address the energy inefficiency problem. By taking advantage of the FM radio characteristics - higher coverage and lower energy consumption than Wi-Fi, our proposed approach uses FM as an always-on point-to-multipoint control channel used to turn off the nodes' Wi-Fi radio interfaces when they are not needed to transmit, receive, or relay data. Numerical and simulation analysis shows that our proposed scheduling mechanism significantly reduces energy consumption, while preserving performance and fairness characteristics.
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