Teleconferencing System Research Articles

A new adaptive filtering algorithm for stereophonic acoustic echo cancellation

This paper addresses the stereophonic acoustic echo cancelation (SAEC) problem in teleconferencing system by adaptive filtering algorithm. We propose a new stereophonic version of the fast normalized least mean square (FNLMS) algorithm. The proposed algorithm is an extended version of the FNLMS algorithm to the stereophonic case with important improvement of the prediction part that becomes stable in the stereophonic case. The basic idea behind the proposed stereophonic fast normalized least mean square (SFNLMS) algorithm is the normalization of the predictor parameter by the inputs variance for each channel. Simulation results of a comparison between the proposed SFNLMS algorithm and the classical SNLMS version in term of convergence speed and stability are presented.

An Improved Double-talk Detection Algorithm for Echo Cancellation in Teleconference System

Echo cancellation commonly employs a double-talk detector (DTD), which is essential to keep the adaptive filter from diverging in the presence of near-end speech. An improved double-talk detection algorithm is proposed to promote the performance of the echo cancellation in teleconference system in the presence of speech issued from the near-end speaker (double-talk). Based on the partitioned block frequency domain adaptive filter algorithm (PBFDAF), the advanced double-talk detection method is presented in this paper constructs a joint correlation coefficient variable to judge the communication state and the variable is applied as a smoothing parameter to the error signal and then get the final output signal. Simulation results show that the improved algorithm can effectively detect the current voice state, eliminate the echo signal, and keep the near-end speaker’s voice well. The performance of the echo cancellation algorithm is improved when both echo and near end signals are simultaneously active by the proposed technique.

Teleconference-based education of epileptic seizure semiology

BackgroundTo evaluate whether a teleconference-based lecture provides similar understanding of seizure semiology to a face-to-face lecture for physicians. MethodsSubjects were 66 physicians consisting of adult and pediatric neurologists, neurosurgeons, psychiatrists, and general practitioners. All attended the 30-minute lecture to introduce various types of seizure semiology using video-clips by one of the authors (Yo.K.) and then joined the comprehensive case conference which discussed three cases in 1.5 h. Group A received the lecture and conference using a teleconference system (N = 43) and Group B attended in person (N = 23) for geographical reasons. After the conference, 32 subjects (23 in Group A and nine in Group B) scored their own post-lecture understanding of seizure semiology using the four-point Likert scale from 1 (not at all) to 4 (very well) as well as the estimated pre-lecture score. Data was analyzed to assess whether their understanding was improved after the lecture. ResultsNo significant difference was found in improvement of understanding after the lecture between Group A (43%) and Group B (22%; p = 0.42). Pre-lecture score of subjects with improved understanding was significantly lower (2.3 +/- 0.2) than those without improvement (3.7 +/- 0.1) (p < 0.05). SignificanceTeleconference-based lectures can be a useful tool to educate seizure semiology for physicians, especially at the inexperienced level, by overcoming geographical limitations.

Mirage and Reality Interplay in Tom Tykwer’s A Hologram for a King

This article discusses 2016 film A Hologram for a King, directed by Tom Tykwer in the context of the interplay between mirage and reality. Set in Saudi Arabia, this film revolves around the story of an American consultant, Alan Clay, who attempts to sell a hollographic teleconferencing system to the king. The film is imbued with captivating and symbolic visuals that point to the interplay between mirage and reality. This article will focus on how the cinematography and mise-en-scene of the film help supporting the interplay between mirage and reality, and to show what the film comments on the interplay in regard to our contemporary world. The method used is a film scene analysis by focusing on the important scenes in the film. The findings show that the director cleverly utilizes cinematic techniques to emphasize the main theme of the film and to offer his own viewpoint on the interplay between mirage and reality.

Study on acoustic improvements by sound-absorbing panels and acoustical quality assessment of teleconference systems

With the development of information and communications technology, conferences and remote education using teleconference systems have become common. When a teleconference system is used, the sound heard in a receiving room includes the acoustic characteristics of both the utterance and receiving rooms, in addition to the characteristics of the transmission via the teleconference system and Internet. Even today, when the digital technology is widely used, quality problems related to sound transmission remain; in particular, the influence of the reverberation of the conference room causes deterioration of the sound quality. Studies aiming to improve the quality of the signal transmission have been conducted; however, there are no acoustic countermeasure methods considering the acoustic characteristics of the two rooms connected by a teleconference system and performing the sound quality evaluation. In this study, focusing on a teleconference system sharing video and audio between two separate rooms, we evaluated the improvement in the sound transmission performance due to the addition of sound absorption to the conference room by examining the correspondence between the subjective assessment results and acoustical physical indexes. Additionally, the acoustical physical indexes that allow evaluating the quality of the sound transmitted via the teleconference system were also examined by comparing with the result of a subjective assessment. Intelligibility tests were conducted, listening difficulty ratings were evaluated, and the impulse response, STI, Clarity (C50), and reverberation time were measured in an actual teleconference system. We observed that, before the addition of sound absorption, the sound was difficult to listen to due to the acoustic characteristics of both of the utterance and receiving rooms. However, by suppressing reverberation in both the utterance and receiving rooms by using sound-absorbing panels, the difficulties in listening was improved. By examination of the correspondence between the subjective assessment results and acoustical physical indexes, we proved that STI and Clarity (C50) are highly correlated with intelligibility. On the other hand, reverberation time was found to be uncorrelated with the intelligibility of the rooms of teleconference systems.

Stroke networks and telemedicine: An Italian national survey.

Stroke is the leading cause of disability and death. Nowadays, clinical benefits of stroke units and thrombolysis in ischemic stroke are evidence-based. Also the benefit of endovascular treatment for acute ischemic stroke has been established. Telemedicine has been used to improve access to care by allowing a neurologist at a remote location to interact with the patient and their family members. Prior studies have shown that the use of telemedicine for acute ischemic stroke is not only safe and effective, but it also increases the utilization of tPA, improving patient outcomes. This study aimed to investigate the diffusion of telemedicine in Italian stroke networks with an online questionnaire to assess: type of stroke care setting, Volume of thrombolysis- thrombectomy/year, access to stroke care between different hospitals, the presence of imaging sharing protocols within the network or patients dispatchment screening; type of network solutions. We have interviewed 24 Italian neurologists, working in large urban areas, from north southward, including Italian islands. In particular, these neurologists represented 14 different regions and 20 countries. A majority of neurologists replying to the survey (47.83%) worked in large general hospitals or smaller general hospitals (26%) and a smaller number of physicians (17.3%) were committed in University Hospital or (8.7%) independent foundation hospitals. The 60.87% of stroke networks involved in the survey had a low thrombolysis/year volume while the 30.43% had a thrombolysis/year volume above 100. According to the survey a local stroke network was established in 87.50% of cases. In the 45.83% of cases, the hospitals care is not homogeneous within the network. A network for the consultation of neuroimaging between hospitals is available in 33.33% of cases. Whitin those describing an active network for Teleconsult the 57.14% used personal devices, while only the 25 % use professional teleconference system, and in 25% of cases used medical devices. Our findings demonstrated a relevant diffusion of Teleconsult in Italian stroke networks. The systems adopted are mostly individual solutions not integrated in protocolled pathways. These findings may encourage a systematization of Telemedicine medical curricula to increase larger access to neurological consults.

Impact of Information and Communication Technologies on Agricultural Education

The present paper highlights the availability, awareness and usage of information and communication technology (ICT) among students of Agricultural Universities in Andhra Pradesh and Telangana. The results revealed that most of the students had the access to ICT tools like projector, computer, University website and mobile, but the tools like e-portfolio, teleconference, videoconference and digital student report card system were not available to most of the students in agricultural colleges. Student's awareness of ICT tools is same as that of availability. Most of the agricultural students were using mobile daily, but occasionally used the computer and projector. Majority of the students had improved their capabilities in concept understanding, academic performance, employment opportunities and higher education opportunities.

Multichannel acoustic echo cancellation exploiting effective fundamental frequency estimation

Multichannel teleconferencing systems exploit multichannel acoustic echo cancellers to weaken the echo replicas due to the acoustic coupling among loudspeakers and microphones. Many issues have to be dealt with to ensure an effective echo cancellation in such systems, including the reduction of the interchannel coherence among channels, the detection of an active remote human speaker, and the identification of the well-known double-talk scenario. In this paper, a comprehensive solution for dealing with the aforementioned aspects is discussed. The core of this solution is the estimation of the fundamental frequency of the audio signal. It is exploited for weakening the linear relation among channels and for tracking the presence of an active human speaker both in the remote room and in the local room of a teleconferencing system. The computational complexity of the presented approach is also reported to support its feasibility in a real scenario. Then, its real-time implementation is presented and validated on the NU-Tech framework, showing its fundamental frequency tracking capability and echo reduction performance both in simulated and real scenarios.

Effect of the horizontal panning on sense of presence in three-dimensional audio system based on multiple vertical panning

We previously proposed a three-dimensional (3D) audio system using the multiple vertical panning (MVP) method to develop a 3D audio system that matches a multi-view 3D video display system (REI display). In this paper, in order to apply our proposed method to the teleconference system, we performed two audio-visual psychological experiments and evaluated the effect of the horizontal panning on the sense of presence in our proposed method. We found that the performance is maintained when four loudspeakers were placed at the position except the edges of the display.

Design and implementation of a teleconferencing system using improved HEVC coding

Teleconferencing has become an indispensable element in any business system, because it offers the opportunity for collaborators to participate in a virtual group while remaining in divergent regions. Teleconferencing also increases productivity, minimizes travel expenses and saves travel time. This paper presents a reliable Teleconference system that utilizes an improved high-efficiency video codec (HEVC) H.265 technology with congestion control. The improvement is based on CU size decision and entropy coding, which provides an adequate approach to enhance the real-time video/IP technology in terms of improved video quality and increased compression ratio compared to the previous codec (H.264) and original HEVC.

A new teleconference system with a fast technique in HEVC coding

Tele-Communications play an important role nowadays. Globalization has led the requirement for traversed communication. Therefore a multimedia system takes an influential act in the comprehensive c...

Only available to a selected few? Is it feasible to rely on a volunteer workforce for complex intervention delivery?

This paper recounts the process of undertaking a randomised controlled trial which was designed to examine the effectiveness of an intervention for socially isolated older people aged 75years and over. It describes the reasons for early cessation of the study and raises the implications of this outcome for policy, practice and research. The intervention under investigation was designed to alleviate loneliness and foster companionship. It involves participants being linked with a small group of others through a teleconferencing system with each group being facilitated by trained volunteers. There was a requirement to recruit and train a minimum of 30 and a maximum of 60 volunteers over 1year to facilitate 20 friendship groups to meet the number of older people required to be recruited to the study. Problems with recruiting and retaining the volunteer workforce by the voluntary sector organisation, who were commissioned to do so, led to the study closing even though older people were recruited in sufficient numbers. The paper draws upon analysis of various data sources from the study to identify the potential reasons. The discussion raises considerations regarding the extent of infrastructure required to deliver community services to vulnerable user groups at scale, identifies some of the issues that need to be addressed if such volunteer-initiated services are to be successful and informs future research programmes in this area.

After interaction

Alex S Taylor (2015) , Interactions 22(5), p. 48-53. It is, arguably, where it all began for interaction. Doug Engelbart’s retrospectively titled “The Mother of All Demos” spectacularly set the scene for what we do in HCI and especially for what we imagine interaction to be. Engelbart and his team showcased a remarkable collection of technologies for seeing and manipulating data. The demo is best known for the introduction of the mouse as an input device, but also presented was an integrated teleconferencing system and the simultaneous collaborative editing of a text document. Think computing in the late 1960s, but with the mouse and something akin to Skype and Google Docs. It’s hard to imagine how extraordinary this must have seemed at a time when telephone adoption was only just reaching a plateau in the U.S. and, for all but the technological elite, the idea of networked computers was the stuff of science fiction or, more likely, just unthought of.

Crowdsourcing vs. laboratory experiments – QoE evaluation of binaural playback in a teleconference scenario

Experiments for the subjective evaluation of multimedia presentations and content are traditionally conducted in a laboratory environment. In this respect common procedures for the evaluation of teleconference systems are no different. The strictly controlled laboratory environment, however, often gives a rather poor representation of the actual use case. Therefore in this study we crowdsourced the evaluation of a teleconference system to perform the evaluation in a real-life environment. Moreover, we used the unique possibilities of crowdsourcing to employ two different demographics by hiring workers from Germany on the one hand and the US and Great Britain on the other hand. The goal of this experiment was to assess the perceived Quality of Experience (QoE) during a listening test and compare the results to results from a similar listening test conducted in the controlled laboratory environment. In doing so, we observed not only intriguing differences in the collected QoE ratings between the results of laboratory and crowdsourcing experiments, but also between the different worker demographics in terms of reliability, availability and efficiency.

Developing an audio network system for teleconferencing with evaluation of audio quality

A teleconference system was developed to transmit speech signals for audio communication with remote users. The hardware system was composed of 3-D microphone arrays to capture directional sound and a wireless headset to provide freedom of movement for users. An application programming interface (API) was used for interaction between the computer and the audio devices, including the microphone, headphone, and ADDA converter, transferring input/output audio signals in real time through the network. For the evaluation of the system, a latency test was performed with a simultaneous recording system in capturing and reproduction positions. The latency from the network procedure was calculated with different buffer sizes, and the lower-delay and smaller-deviation buffer was selected. In addition, the transmitted audio signals were compared with the input signals in terms of signal patterns and frequency responses. The resulting audio qualities in the time and frequency domain were suitable for a teleconferencing system.

Adaptive estimation and reshaping of room impulse response

In this paper, we focus on the reverberation depression in scenarios such as hand-free telephone and teleconference system applications. The combination of cross-relation based blind room impulse response (RIR) estimation and the p-norm based channel reshaping leads to this adaptive reverberation depression scheme. The normalized multi-channel frequency-domain least-mean-square (NMCFLMS) algorithm is used for RIR estimation and the p-norm optimization approach for channel reshaping. Simulations show that it is possible to establish such a post-processing system for reverberation depression. Listening tests verified that reverberation is hardly heard after channel reshaping.

Modified Approach for VSS NLMS Algorithm for Echo Cancellation in Teleconference System

communication or wireless phones have become need of everyone in this technological era of global communication. Wireless phones not only provide voice communication, they can also easily be used for other services. But voice quality is always preferable over other services of cellular networks. This demand of superior voice quality, just as like as wired line, over a wireless network has developed and is known as echo cancellation. The main aim of the acoustic echo cancellation is to remove the echoes present in desired signal and to provide echo free speech to the listeners. In this paper, a new approach for acoustic echo cancellation (1) and double talk detection for a teleconference system in non stationary environmental conditions is proposed. In this approach the impulse response of the loud speaker is assumed to be available and is estimated from the digital low pass filter. This approach is more common in the sense that it is applied to all existing algorithms. Performance evaluation of the proposed algorithm is known by calculating echo return loss enhancement (ERLE). This approach shows better performance for non stationary environment and reduces the complexity of both acoustic echo cancellation and double talk detection algorithms and this can be implemented with the help of MATLAB.

Double-talk robust acoustic echo cancellation for CD-quality hands-free videoconferencing system

A novel monaural acoustic echo cancellation method developed for a 20-kHz wideband hands-free videoor teleconferencing system is presented. The method can effectively reduce undesired acoustic echo included in a signal arriving at a microphone from a loudspeaker and can emphasize the target talker's voice when near-end and farend talkers speak simultaneously (i.e. double-talk). The method estimates a power frequency response of an acoustic echo path between a loudspeaker and microphone (acoustic coupling level) whether or not double-talk has occurred, then calculates a post-filter that effectively reduces the undesired echo. In the echo cancellation processing, the calculation complexity is reduced to make the processing suitable for real-time implementation by using a low-complexity subband approach that employs a new subband filtering algorithm. Experiments were conducted to examine the performance of the proposed method. The results indicated that the proposed method delivered natural-sounding near-end speech even during double-talk periods while sufficiently suppressing the undesired echo.

Perceived Risks and Ict Use

The objective of this research is to investigate the types of problems and their associated perceived risks as well as the effects of risks perceived on frequently used information communication technologies (ICTs) by globally distributed software development teams. We focused on perceived risk in reception, understanding and action and studied two global software teams that were at different software development phases (i.e. requirements analysis versus development and maintenance). Data for this research was collected from a leading global IT consulting company and we found that instant messaging, email and teleconferencing system were frequently used by the two teams. Our results indicate that perceived risks in reception and action were encountered by members in the systems development and maintenance phase. Additionally, we also found differences on the effects of perceived risks on the use of instant messaging, email and teleconferencing system between the teams.

Floating Autostereoscopic 3D Display with Variable Viewing Area for Multi-View Teleconference System

Floating Autostereoscopic 3D Display with Variable Viewing Area for Multi-View Teleconference System