Tohru Ifukube

Elderly user evaluation of mobile touchscreen interactions

Smartphones with touchscreen-based interfaces are increasingly used by non-technical groups including the elderly. However, application developers have little understanding of how senior users interact with their products and of how to design senior-friendly interfaces. As an initial study to assess standard mobile touchscreen interfaces for the elderly, we conducted performance measurements and observational evaluations of 20 elderly participants. The tasks included performing basic gestures such as taps, drags, and pinching motions and using basic interactive components such as software keyboards and photo viewers. We found that mobile touchscreens were generally easy for the elderly to use and a weeks experience generally improved their proficiency. However, careful observations identified several typical problems that should be addressed in future interfaces. We discuss the implications of our experiments, seeking to provide informal guidelines for application developers to design better interfaces for elderly people.

A tactile display for presenting quality of materials by changing the temperature of skin surface

Tactile information processing was studied based on psychophysical experiments in order to design a tactile display for tele-existence robots or virtual reality devices. First, the identification characteristics of the tactile sensing concerned with the quality of materials were investigated when human fingertips touched the surface of various materials in a vertical direction. In addition to obtaining the tactile characteristics, the temperature change of the skin surface of a fingertip was measured when the fingertip contacted the surface of materials. From these experimental results, the temperature difference from the normal skin temperature was found to be very important to recognize what kind of materials contacted the skin surface. Next, the tactile display for presenting the quality of materials was designed on the basis of the above experimental results. The tactile display system was composed of a Peltier module and a PID controller.<<ETX>>

A portable digital speech-rate converter for hearing impairment

A real-time hand-sized portable device that slows speech speed without changing the pitch is proposed for hearing impairment. By using this device, people can listen to fast speech at a comfortable speed. A combination of solid-state memory recording and real-time digital signal processing with a single chip processor enables this unique function. A simplified pitchsynchronous, time-scale-modification algorithm is proposed to minimize the complexity of the DSP operation. Unlike the traditional algorithm, this dynamic-processing algorithm reduces distortion even when the expansion rate is only just above 1. Seven out of 10 elderly hearing-impaired listeners showed improvement in a sentence recognition test when using speech-rate conversion with the largest expansion rate, although no improvement was observed in a word recognition test. Some subjects who showed large improvement had limited auditory temporal resolution, but the correlation was not significant. The results suggest that, unlike conventional hearing aids, this device can be used to overcome the deterioration of auditory ability by improving the transfer of information from short-term (echoic) memory into a more stable memory trace in the human auditory system.

Effects on the location of the centre of gravity and the foot pressure contribution to standing balance associated with ageing

The aim was to analyse the limitation of the head and lumbar movements in relation to the centre of gravity which is needed to maintain standing balance with ageing. The participants of the study were 25 healthy volunteers divided into two age categories, the young group (mean 22.4 +/- 2.7 years) and the elderly group (mean 71.2 +/- 3.6 years). The instruments for measuring the movements of the lumbar region and head and the centre of pressure (COP) were a 3-D motion analysis system and a force plate. In addition, the peak foot pressure was measured during standing using the F-Scan system. The participants were first asked to stand relaxed for 10 s. They then shifted from the starting position to the four directions of sway: anterior, posterior, right and left. They were asked to maintain standing balance at the maximal distance position for each sway as much as possible for 10 s. Analysis of parameters was performed by measuring the average maximal linear displacement (cm) of the head and lumbar markers, the COP (cm), and the peak foot pressure (% of body weight per cm2) in each participant. The data of the young group for lumbar maximal displacement were greater than those of the elderly group in the anterior, posterior and lateral sways. A significant difference between the young and elderly data was found in the posterior sway. According to the data of the heads maximal displacement, the elderly groups data were greater than the young groups data in all sways, except for the anterior side. For the data of peak foot pressure in the posterior sway, the elderly groups data was greater than the young groups data. The forefoot area data of the young group was significantly greater than that of the elderly group, and the heel area data of the elderly was significantly greater than that of the young group in the right sway. The results suggest that the maximal displacement of head and lumbar positions and the toes muscle activity in the forefoot are important factors associated with the centre of gravity in elderly adults. It is postulated that each base of support area of the older adults in smaller than that of younger adults. These variables could be made available as a clinical test for the degree of poor balance.

A preliminary study of clinical assessment of left unilateral spatial neglect using a head mounted display system (HMD) in rehabilitation engineering technology

PurposeUnilateral spatial neglect (USN) is a common syndrome in which a patient fails to report or respond to stimulation from the side of space opposite a brain lesion, where these symptoms are not due to primary sensory or motor deficits. The purpose of this study was to analyze an evaluation process system of USN in various visual fields using HMD in order to understand more accurately any faults of USN operating in the object-centred co-ordinates.MethodEight stroke patients participated in this study and they had Left USN in clinical test, and right hemisphere damage was checked by CT scan. Assessments of USN were performed the BIT common clinical test (the line and the stars cancellation tests) and special tests the zoom-in condition (ZI) condition and the zoom-out condition (ZO) condition. The subjects were first evaluated by the common clinical test without HMD and then two spatial tests with HMD. Moreover, we used a video-recording for all tests to analyze each subjects movements.ResultsFor the line cancellation test under the common condition, the mean percentage of the correct answers at the left side in the test paper was 94.4%. In the ZI condition, the left side was 61.8.% and the right side was 92.4.%. In the ZO condition, the left side was 79.9% and the right side was 91.7.%. There were significant differences among the three conditions. The results of the stars cancellation test also showed the same tendency as the line bisection test.ConclusionThe results showed that the assessment of USN using a technique of HMD system may indicate the disability of USN more than the common clinical tests. Moreover, it might be hypothesized that the three dimensional for USN test may be more related to various damage and occurrence of USN than only the two dimensional test.

Proposal of a new method for narrowing and moving the stimulated region of cochlear implants: animal experiment and numerical analysis

The authors have proposed the tripolar electrode stimulation method (TESM) for narrowing the stimulation region and continuously moving the stimulation site for cochlear implants. The TESM stimulates the auditory nerve array using three adjacent electrodes which are selected among the electrodes of an electrode array within the lymphatic fluid. Current is emitted from each of the two lateral electrodes and received by the central electrode. The current received by the central electrode is made equal to the sum of the currents emitted from the lateral electrodes. Here, the authors evaluate whether or not TESM works according to a theory which is based on numerical analysis using an electrical equivalent circuit model of the auditory nerve fibers. In this simulation, the sums of the excited model fibers are compared to the compound action potentials (CAPs) which the authors obtained through animal experiments. To identify the main parameter while maintaining the amplitude of the CAP (the sum of the fired fibers), the authors assumed the presence of some parameters from the radial current density profile. In the case of the width value among the parameters being kept constant, the amplitude of the CAP was almost constant; thus, the number of the fired fibers was also almost constant. The width value equals the distance between the points at which the profile of the radial current density of the electrode array and the line of the radial threshold current density of the electrode array intersect. It is possible to determine the measure of the stimulation region or site by controlling the width value and the ratios of the currents emitted from the lateral electrodes. As a result, the authors succeeded in narrowing the stimulation region by controlling the sum of the currents emitted from the two lateral electrodes. Also they succeeded in continuously moving the stimulation site by modifying the currents emitted from the two lateral electrodes.

Effects of an Eyeglass-free 3-D Display on the Human Visual System

PurposeTo investigate the effect on the human visual system of viewing 3-dimensional (3-D) computer graphics (CG) images with an eyeglass-free rear-cross-lenticular-type 3-D display.MethodsPositive accommodation velocity (GRAD) during the accommodative step response was measured in ten healthy young adults before and after they viewed CG images. Although the distance between the viewer and the 3-D display was 600 mm, the apparent distance between the viewer and the virtual object was varied (515, 600, and 722 mm) by changing the visual disparity.ResultsA significant slowdown of average GRAD was observed by 60 min after a 30-min 3-D viewing of 3-D CG images [P ≪ 0.05, analysis of variance (ANOVA)] but not after a 30-min viewing of the CG images on a 2-D display or after a 15-min 3-D viewing. When the virtual object was at 722 mm, a significant slowdown of average GRAD was observed only at 30 min after the 30-min 3-D viewing (P ≪ 0.05, ANOVA). When the virtual object was at 515 mm, a significant slowdown of average GRAD was observed at 30 and 60 min after the 3-D viewing (P ≪ 0.05, ANOVA).ConclusionsThe effect on the human visual system of 3-D viewing of 3-D CG images depends on both the duration of the viewing and the apparent distance between the viewer and the virtual objects. Jpn J Ophthalmol 2004;48:1–6

Analysis and perception of spectral 1/f characteristics of amplitude and period fluctuations in normal sustained vowels

Two kinds of fluctuations are always observed in the steady parts of normal sustained vowels. One is amplitude fluctuation, defined as the cyclic changes of maximum peak amplitudes. The other is period fluctuation, defined as the cyclic changes of pitch periods. The primary purpose of this paper is to present quantitative descriptions of amplitude and period sequences obtained from normal sustained vowels. These fluctuation sequences consisted of maximum peak amplitudes or pitch periods extracted successively from 512 consecutive pitch periods in the steady part. Results of the frequency analysis indicated that their frequency characteristics seemed to be subject to the spectral 1/f power law. In order to investigate the possibility that the frequency characteristics of the fluctuation sequences influence the voice quality of sustained vowels, psychoacoustic experiments were conducted. Amplitude and period sequences evaluated in the experiments were spectral 1/f0 (white noise), 1/f, 1/f2, and 1/f3 sequences, respectively. The experimental results indicated that the subjective voice quality of synthesized sustained vowels could reflect the differences in the frequency characteristics of the fluctuation sequences.

A case study of new assessment and training of unilateral spatial neglect in stroke patients: effect of visual image transformation and visual stimulation by using a head mounted display system (HMD)

BackgroundUnilateral spatial neglect (USN) is most damaging to an older stroke patient who also has a lower performance in their activities of daily living or those elderly who are still working. The purpose of this study was to understand more accurately pathology of USN using a new HMD system.MethodsTwo stroke patients (Subject A and B) participated in this study after gaining their informed consent and they all had Left USN as determined by clinical tests. Assessments of USN were performed by using the common clinical test (the line cancellation test) and six special tests by using HMD system in the object-centered coordinates (OC) condition and the egocentric coordinates (EC) condition. OC condition focused the test sheet only by a CCD. EC condition was that CCD can always follow the subjects movement. Moreover, the study focused on the effect of the reduced image condition of real image and the arrows.ResultsIn Patient A who performed the common test and special tests of OC and EC conditions, the results showed that for the line cancellation test under the common condition, both of the percentage of the correct answers at the right and left sides in the test sheet was 100 percent. However, in the OC condition, the percentage of the correct answers at the left side in the test sheet was 44 percent and the right side was 94 percent. In the EC condition, the left side was 61 percent and the right side was 67 percent. In Patient B, according to the result of the use of reduced image condition and the arrows condition by HMD system, these line cancellation scores more increased than the score of the common test.ConclusionsThe results showed that the assessment of USN using an HMD system may clarify the left neglect area which cannot be easily observed in the clinical evaluation for USN. HMD may be able to produce an artificially versatile environment as compared to the common clinical evaluation and treatment.

A basic study of a force display using a metal hydride actuator

A new method of a force display is proposed for presenting the sense of force to an elbow joint using a metal hydride (MH) actuator to be used in artificial reality and tele-existence robot. An MH actuator is very suitable for the force display because it works smoothly without any noise. In addition, the actuator is compact, light weight, and it has an adequate compliance. From simple tests, it was found that the actuator could raise a load of 10 kg up to a height of 50 mm at a speed of 9 mm/sec using a 6 g MH alloy. A force display made by the MH actuator was attached to a human elbow joint and two psychophysical experiments were carried out to investigate whether or not the actuator is useful for the force display to create an artificial reality.<<ETX>>