On the evaluation of the conversational speech quality in telecommunications

International audienceIn this paper we propose an objective method to assess speech quality in the conversational context by taking into account the talking and listening speech qualities and the impact of delay. This approach is applied to the results of four subjective tests on the effects of echo, delay, packet loss and noise. The dataset is divided into training and validation sets. For the training set, a multiple linear regression is applied to determine a relationship between conversational, talking and listening speech qualities and the delay value. The multiple linear regression leads to an accurate estimation of the conversational scores with high correlation and low error between subjective and estimated scores, both on the training and validation sets. In addition, a validation is performed on the data of a subjective test found in the literature which confirms the reliability of the regression. The relationship is then applied to an objective level by replacing talking and listening subjective scores with talking and listening objective scores provided by existing objective models, fed by speech signals recorded during the subjective tests. The conversational model achieves high perfor- mance as revealed by comparison with the test results and with the existing standard methodology “E-model”, presented in the ITU-T (International Telecommunication Union) Recommendation G.107

Resistive Random Access Memories (RRAMs) Based on Metal Nanoparticles

It is demonstrated that planar structures based on silver nanoparticleshosted in a polymer matrix show reliable and reproducible switching properties attractive for non-volatile memory applications. These systems can be programmed between a low conductance (off-state) and high conductance (on-state) with an on/off ratio of 3 orders of magnitude, large retention times and good cycle endurance. The planar structure design offers a series of advantages discussed in this contribution, which make it an ideal tool to elucidate the resistive switching phenomena

New electronic memory device concepts based on metal oxide-polymer nanostructures planer diodes

Nanostructure silver oxide thin films diodes can exhibit resistive switching effects. After an electroforming process the device can be programmed between a low conductance (off-state) and high conductance (on- state) with a voltage pulse and they are already being considered for non-volatile memory applications. However, the origin of programmable resistivity changes in a network of nanostructure silver oxide embedded in polymer is still a matter of debate. This work provides some results on a planer diode which may help to elucidate resistive switching phenomena in nanostructure metal oxide diodes. The XRD pattern after switching appears with different crystalline planes, plus temperature dependent studies reveal that conduction of both on and off states is weak thermal activated. Intriguing the carrier transport is the same for both on and off-states. Difference between states comes from the dramatic changes in the carrier density. The main mechanism of charge transport for on-state is tunneling. The charge transport leads to SCLC in higher voltages pulse for the off state. The mechanism will be explained based on percolation concepts

Relationship between performance, heart rate variability and clinical symptoms in elite football: A case study

Introduction Matches and high-intensity training put important load on elite football players, which may result in performance decrease and physiological alterations (Meeusen et al., 2013). Positive correlations between heart rate variability (HRV) athletic performance have been reported (Buchheit et al., 2012) but the measurements were not related to match performance. Studies investigating the relationship between HRV and in-match performance data are scarce and none identified typologies of fatigue (Schmitt et al., 2015). This is a case study of one elite football player that showed a typical autonomic dysfunction corresponding to a fatigue state with associated clinical symptoms. Methods A male elite football player playing in French Ligue 1 and continental competitions recorded his beat-to-beat heart rate (Polar H10) during an orthostatic test (5 min supine followed by 5 min standing) systematically 2 days before every match during a series of 8 matches at the rate of 1 match/week. These recordings allowed the assessment of mean heart rate (HR), power spectrum in the low- and high-frequency bands (LF and HF). During each match a GNSS sensor (Vector S7, Catapult) allowed the recording of total distance, acceleration/deceleration above 2m/s. Moreover, the number of passes, passes to the final thirty meters and number of duels and duels won were quantified by video analysis. Results The player played the entirety of the 8 games mostly as a midfielder and sometimes as a left back. Heart rate in the supine position was inversely correlated to the number of passes and successful passes to final third (R = -0.67, p < 0.05) whilst LF in the standing position was correlated to the duels and duels won (R = 0.75, p < 0.05). In addition, log(HF) was correlated to the number of acceleration during the match whilst log(LF) was correlated with the total distance ran. The player displayed on several occasions a fatigue profile characterized by a parasympathetic hypertonia in the standing position, which ultimately resulted in the player fainting on the pitch. Discussion/Conclusion HRV during an orthostatic test two days before a match could be useful in identifying fatigue profiles associated with decreased performances and clinical symptoms. Such methods should be used on an entire season and entire squad to better characterize the fatigue profiles in elite football and may help better adapt training sessions. References Buchheit, M., Simpson, M. B., Al Haddad, H., Bourdon, P. C., & Mendez-Villanueva, A. (2012). Monitoring changes in physical performance with heart rate measures in young soccer players. European Jopurnal of Applied Physiology, 112, 711–723. https://doi.org/10.1007/s00421-011-2014-0 Meeusen, R., Duclos, M., Foster, C., Fry, A., Gleeson, M., Nieman, D., Raglin, J., Rietjens, G., Steinacker, J., & Urhausen, A. (2013). Prevention, diagnosis, and treatment of the overtraining syndrome: Joint consensus statement of the European College of Sport Science and the American College of Sports Medicine. Medicine & Science in Sports & Exercise, 45(1), 186–205. https://doi.org/10.1249/mss.0b013e318279a10a Schmitt, L., Regnard, J., Parmentier, A. L., Mauny, F., Mourot, L., Coulmy, N., & Millet, G. P. (2015). Typology of “Fatigue” by heart rate variability analysis in elite nordic-skiers. International Journal of Sports Medicine, 36(12), 999–1007. https://doi.org/10.1055/s-0035-154888