Saso Tomazic

A user study of auditory versus visual interfaces for use while driving

This paper describes a user study on interaction with a mobile device installed in a driving simulator. Two new auditory interfaces were proposed and their effectiveness and efficiency were compared to a standard visual interface. Both auditory interfaces consisted of spatialized auditory cues representing individual items in the hierarchical structure of the menu. In the first auditory interface all items of the current level of the menu were played simultaneously. In the second auditory interface only one item was played at a time. The visual interface was shown on a small in-vehicle LCD screen on the dashboard. In all three cases, a custom-made interaction device (a scrolling wheel and two buttons) attached to the steering wheel was used for controlling the interface. The driving performance, task completion times, perceived workload and overall user satisfaction were evaluated. The experiment proved that both auditory interfaces were effective to use in a mobile environment, but were not faster than the visual interface. In the case of shorter tasks, e.g. changing the active profile or deleting an image, the task completion times were comparable for all interfaces; however, both the driving performance was significantly better and the perceived workload was lower when using the auditory interfaces. The test subjects also reported a high overall satisfaction with the auditory interfaces. The latter were labelled as easier to use, more satisfying and more adequate for performing the required tasks than the visual interface. The results of the survey are not surprising as there is a stronger competition for the visual attention between the visual interface and the primary task (driving the car) than in the case of using the auditory interface. So although both types of interfaces were proven to be effective, the visual interface was less efficient as it strongly distracted the user from performing the primary task.

Multiple spatial sounds in hierarchical menu navigation for visually impaired computer users

This paper describes a user study on the benefits and drawbacks of simultaneous spatial sounds in auditory interfaces for visually impaired and blind computer users. Two different auditory interfaces in spatial and non-spatial condition were proposed to represent the hierarchical menu structure of a simple word processing application. In the horizontal interface, the sound sources or the menu items were located in the horizontal plane on a virtual ring surrounding the users head, while the sound sources in the vertical interface were aligned one above the other in front of the user. In the vertical interface, the central pitch of the sound sources at different elevations was changed in order to improve the otherwise relatively low localization performance in the vertical dimension. The interaction with the interfaces was based on a standard computer keyboard for input and a pair of studio headphones for output. Twelve blind or visually impaired test subjects were asked to perform ten different word processing tasks within four experiment conditions. Task completion times, navigation performance, overall satisfaction and cognitive workload were evaluated. The initial hypothesis, i.e. that the spatial auditory interfaces with multiple simultaneous sounds should prove to be faster and more efficient than non-spatial ones, was not confirmed. On the contrary-spatial auditory interfaces proved to be significantly slower due to the high cognitive workload and temporal demand. The majority of users did in fact finish tasks with less navigation and key pressing; however, they required much more time. They reported the spatial auditory interfaces to be hard to use for a longer period of time due to the high temporal and mental demand, especially with regards to the comprehension of multiple simultaneous sounds. The comparison between the horizontal and vertical interface showed no significant differences between the two. It is important to point out that all participants were novice users of the system; therefore it is possible that the overall performance could change with a more extensive use of the interfaces and an increased number of trials or experiments sets. Our interviews with visually impaired and blind computer users showed that they are used to sharing their auditory channel in order to perform multiple simultaneous tasks such as listening to the radio, talking to somebody, using the computer, etc. As the perception of multiple simultaneous sounds requires the entire capacity of the auditory channel and total concentration of the listener, it does therefore not enable such multitasking.

Spatial sound generation using HRTF created by the use of recursive filters

Generating spatial sound and playing it through headphones is a demanding task, since two important factors, ILD - inter-aural level difference and ITD - inter-aural time difference, need to be taken into consideration. The problem can be solved by the use of head related transfer functions (HRTF) which represent a set of empirically measured functions, one for each spatial direction. The complete reconstruction of HRTF is possible through the use of finite impulse response (FIR) filters with 512 coefficients each. Since the spectrum of HRTF consists of distinctive maximums and minimums, the spectrum could be approximated by the use of resonators and notch filters. The approximation of the complete spectrum (20 Hz - 20 kHz) could be done by the use of six resonators and one notch filter. Our approach to spatial sound generation using HRTF created by the use of recursive (IIR) filters presents a practical and computationally effective solution. It also indicates a way to uniformly model all factors connected to spatial sound perception.

Long term evolution: Towards 4th generation of mobile telephony and beyond

Long term evolution (LTE) is the next major step towards 4th generation of mobile communications. LTE introduces a new radio access network with technologies that offer higher data rates, efficiency and quality of services as well as lower costs and the integration with the existing open standards.

Spatial Auditory Interface for an Embedded Communication Device in a Car

In this paper we evaluate the safety of the driver when using an embedded communication device while driving. As a part of our research, four different tasks were preformed with the device in order to evaluate the efficiency and safety of the drivers under three different conditions: one visual and two different auditory conditions. In the visual condition, various menu items were shown on a small LCD screen attached to the dashboard. In the auditory conditions, the same menu items were presented with spatial sounds distributed on a virtual ring around the users head. The same custom-made interaction device attached to the steering wheel was used in all three conditions, enabling simple and safe interaction with the device while driving. The auditory interface proved to be as fast as the visual one, while at the same time enabling a significantly safer driving and higher satisfaction of the users. The measured workload also appeared to be lower when using the auditory interfaces.

Fast file existence checking in archiving systems

This article presents a new Fast Hash-based File Existence Checking (FHFEC) method for archiving systems. During the archiving process, there are many submissions which are actually unchanged files that do not need to be re-archived. In this system, instead of comparing the entire files, only digests of the files are compared. Strong cryptographic hash functions with a low probability of collision can be used as digests. We propose a fast algorithm to check if a certain hash, that is, a corresponding file, is already stored in the system. The algorithm is based on dividing the whole domain of hashes into equally sized regions, and on the existence of a pointer array, which has exactly one pointer for each region. Each pointer points to the location of the first stored hash from the corresponding region and has a null value if no hash from that region exists. The entire structure can be stored in random access memory or, alternatively, on a dedicated hard disk. A statistical performance analysis has been performed that shows that in certain cases FHFEC performs nearly optimally. Extensive simulations have confirmed these analytical results. The performance of FHFEC has been compared to the performance of a binary search (BIS) and B+tree, which are commonly used in file systems and databases for table indices. The results show that FHFEC significantly outperforms both of them.

Spatial Auditory Human-Computer Interfaces

This book focuses on a special group of auditory interfaces using spatial sound for the representation of information. The addition of information on the location of a selected sound source or a group of sources shows many advantages over a mere single-channel audio. This survey explains the most important limitations of the human hearing system and the perception of spatial sound. It also includes some technical background and basic processing and programming techniques for the creation and reproduction of spatial sounds with different audio equipment. Spatial auditory interfaces have evolved significantly in the last couple of years and can be found in a variety of environments where visual communication is obstructed or completely blocked by other activities, such as walking, driving, flying, operating multimodal virtual displays, etc. An entire chapter of this survey is dedicated to the most important areas of spatial auditory displays: mobile devices and computers, virtual environments, aircrafts and vehicles, visually impaired and blind computers users, and brain-computer interfaces.

Concept modeling: From origins to multimedia

The origins of concept modeling are in the field of artificial intelligence. This is where the initial algorithms were introduced first. With the emerging developments in the field of multimedia systems, a strong need is generated to examine and implement concepts-based retrieval of multimedia-contents, from large data bases or from the Internet. The early works were based on appropriate modifications of classical approaches. The latest developments utilize the algorithms that make sense only in the case of multimedia systems. This paper presents a number of classical approaches to concept modeling and their applicability to multimedia. Then it discusses a number of approaches introduced specifically for multimedia. Finally it presents an approach which was fully implemented and tested in an academic environment for industry needs.

Methodology for Written and Oral Presentation of Research Results

The purpose of the methodology described in this paper is to highlight an effective method for the organization of research results into written and oral forms. Authorities within supervising universities have realized that strong research by a candidate is often obscured by poor presentation, leading to the paper being ignored by the research community and journal reviewers. On the basis of their academic background, the writers of this paper decided to form a set of clear guidelines for writing research papers and giving oral presentations aimed at helping Ph.D. students. To support the effectiveness of the methodology proposed, a statistical analysis has been conducted. The methodology described in this paper was initially intended for use in the fields of computer engineering; however, it is applicable more widely. In conclusion, if the methodology reported in this paper is followed strictly, it is much less likely that a good piece of work would be rejected for publication, and/or remain anonymous, due to inadequate presentation.

Comments on spectral efficiency of VMSK

This article demonstrates that no ultra narrow band modulation (UNBM) method, which includes very minimum shift keying (VMSK) and VPSK, can have substantially greater efficiency than conventional methods, such as quadrature amplitude modulation (QAM), in transmission in the same frequency band.