The purpose of this study was to clarify the kinetics of muscle oxygenation by near infrared spectroscopy (NIRS) in the phase of the decreasing force, especially the pre- and post-phases of the inflection point, during repeated rhythmic grip (RRG) of 30 grips/min⁻¹ for 6 minutes. The inflection point was the time at which the decreasing speed of the grip force changed markedly. It was calculated statistically from two regression lines fitted to each decreasing phase by applying a two-phase regression model. Ten healthy males performed the RRG for 6 minutes. Total Hb and Oxy-Hb decreased rapidly about 10 sec (7.0±5.9 sec, 9.8±5.4 sec, respectively) corresponding to the value decreasing by 90% MVC after the onset of gripping. Deoxy-Hb was maintained at a high value for 76.2±27.9 sec, corresponding to the value decreasing by 70–80% MVC. These phases are considered to be the states where oxygen was not satisfactorily supplied to the active muscles because of the obstruction of blood flow caused by an increase in the intra-muscular pressure. Deoxy-Hb decreased for 120±21.3 sec after reaching the highest value, and then reached an almost steady state at a higher level than the rest. After this phase, muscle oxygenation kinetics enters the state where oxygen is satisfactorily supplied to active muscles. We considered that the relationship between oxygen supply and demand differs during the initial and the latter phases in RRG. The changing phase in the decreasing speed of the grip force, namely the inflection point of the decreasing force, significantly correlated with the changing phase of the Oxy-Hb and Deoxy-Hb kinetics. The inflection point of the decreasing force seems to correspond to the phase where oxygen supply cannot meet oxygen demand and the increase of Deoxy-Hb. We infer that the pre- and post-phases of the inflection point depend on different physiological factors.

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Chair-seat height affects the burden on the lower-limbs during sit-to-stand (STS) movement. Previous studies used the same height chair, attaching importance to practicability, but the difference in each subject's lower thigh length may relate to the burden on the lower-limbs. This study aimed to examine the influence of different lower thigh lengths on floor reaction force and lower-limb strength during an STS movement. Thirty young-adult male subjects participated in this study (age: 22.7±2.6 yr, height: 172.8±4.8 cm, body-mass: 66.3±5.2 kg). The subjects were divided into three groups (G1>42 cm, 42 cm≥G2≥38 cm, 38 cm>G3) based on lower thigh length (G1: 44.1±2.5 cm, G2: 39.8±1.3 cm, G3: 34.3±2.1 cm). Namely, G1 was characterized by lower thigh length longer than 105% of 40 cm, G2 by 95–105% of lower thigh length and G3 by lower thigh length less than 95% of 40 cm, respectively. Subjects performed an STS movement twice from chairs at 40 cm-height and height adjusted by the lower thigh length of each subject. Vertical floor reaction force and electromyogram (EMG) on the rectus femoris and tibialis anterior muscles during an STS movement were measured to evaluate the force of knocking over and the burden on the lower-limbs. Fifteen parameters regarding floor reaction force (10) and EMG (5) were selected for analyses. Significant differences were found in floor reaction force at hip-syneresis (F1) and the impulse between hip-syneresis and appearance of the peak floor reaction force (F2). G1 was greater than G2 for the former, and G3 for the latter. Significant differences were found in active muscle mass of the tibialis anterior from the beginning of an STS movement to hip-syneresis (TE1) and peak active muscle level of the tibialis anterior (TE6). G1 was greater than G2 for the former, and G2 and G3 for the latter. It was suggested that when an STS movement is performed using a chair with the same height for each subject, the load imposed on the subject's leg at the time of an STS movement and the STS movement achievement strategy differed since chair seat height changes relatively by the difference in lower thigh length. Moreover, it is thought that the difference in these load conditions and movement strategies occurs when the chair seat height of a subject's lower thigh length is longer than 110%. When conducting the ability to achieve STS movement rating test, chair seat height considering each subject's lower thigh length may be needed.

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The purpose of this study was to investigate the effects of a floor heating and air conditioning system on thermal responses of the elderly. Eight elderly men and eight university students sat for 90 minutes in a chair under the following 3 conditions: air conditioning system (A), floor heating system (F) and no heating system (C). The air temperature of sitting head height for condition A was 25°C, and the maximum difference in vertical air temperature was 4°C. The air and floor temperature for condition F were 21 and 29°C, respectively. The air temperature for condition C was 15°C. There were no significant differences in rectal temperature and mean skin temperature between condition A and F. Systolic blood pressure of the elderly men in condition C significantly increased compared to those in condition A and F. No significant differences in systolic blood pressure between condition A and F were found. The percentage of subjects who felt comfortable under condition F was higher than that of those under condition A in both age groups, though the differences between condition F and A was not significant. Relationships between thermal comfort and peripheral (e.g., instep, calf, hand) skin temperature, and the relationship between thermal comfort and leg thermal sensation were significant for both age groups. However, the back and chest skin temperature and back thermal sensation for the elderly, in contrast to that for the young, was not significantly related to thermal comfort. These findings suggested that thermal responses and physiological strain using the floor heating system did not significantly differ from that using the air conditioning system, regardless of the subject age and despite the fact that the air temperature with the floor heating system was lower. An increase in BP for elderly was observed under the condition in which the air temperature was 15°C, and it was suggested that it was necessary for the elderly people to heat the room somehow in winter. Moreover, it is particularly important for elderly people to avoid a decrease in peripheral skin temperature, and maintain awareness of the warmth of peripheral areas, such as the leg, in order to ensure thermal comfort.

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The purpose of the present study was to determine the fluctuation in cardiovascular reactivity to mental stress during the menstrual cycle by comparing heart rate variability (HRV), and other physiological and psychological data in females with those in males. Cardiovascular reactivity to two mental tasks was measured in 14 females during the follicular and luteal phase of menstruation over two menstrual cycles. The same tasks were subsequently given to a matched pair of males (N=14), at the same intervals as their corresponding females. Heart rate, blood pressure and HRV were used as indices of cardiovascular reactivity. Subjective mental workload was measured at the end of each task. Power spectral analysis of HRV showed that the high frequency (HF) component in HRV decreased more during the luteal phase than the follicular phase. The low frequency (LF) component in HRV and the LF/HF ratio in the luteal phase were significantly higher than that in the follicular phase. The LF component and the LF/HF ratio were significantly lower in females than in males; conversely, the HF component was significantly higher in females than in males. Neither significant effects of menstrual cycle, gender and mental stress nor any significant interactions were found for mental workload. These findings indicate that sympathetic nervous activity in the luteal phase is significantly greater than in the follicular phase whereas parasympathetic nervous activity is predominant in the follicular phase. The results also suggest that predominance of sympathetic nervous activity in males compared with a dominant parasympathetic nervous activity in females.

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A number of environmental and metabolic stimuli rapidly induce the expression of several highly conserved proteins such as heat shock proteins (HSPs) or stress proteins. The purpose of this study was to investigate the effects of a single bout of submaximal exercise in varying ambient temperatures on cardiac and skeletal muscle. Adult male Sprague-Dawley rats were randomly placed in one of three ambient temperature groups; control (23°C), hot (41°C) and cool (11°C). Each exercise bout consisted of treadmill running at 17 m/min and 0% grade. Tissue HSP70 levels for all groups were determined using analysis of variance in two factorial design (2×3). Baseline rectal temperature was similar for all three groups. In the control and hot temperature groups, final rectal temperatures differed from the baseline values (p<.05). The rectal temperature from the control/exercise group were 38.5±0.3°C at rest and 39.8±0.3°C at exhaustion, the hot/exercise group were 38.4±0.3°C at rest and 41.2±0.9°C at exhaustion and the cool/exercise group were 38.2±0.3°C at rest and 38.5±0.2°C at exhaustion. The running time was 102.0±39.5 min at the control/exercise group, 44.1±18.0 min at the hot/exercise group, and 55.4±11.9 min at the cool/exercise group. The level of soleus, cardiac and extensor digitorium longus (EDL) HSP70 in cool temperature does not change during a single bout of submaximal exercise. Whereas a single bout of submaximal exercise in hot and control ambient temperatures increases HSP70 accumulation in locomotor muscles, such as the soleus and cardiac, but not in the EDL tissue. This study shows that the changes of HSP70 level induced by a single bout of submaximal exercise at various ambient temperatures (control, hot and cool) depend on the rectal temperature.

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An effective silencer for an air conditioning duct is studied. A duct with an acoustically soft boundary is employed as an effective silencer. On the acoustically soft boundary the sound pressure is zero and it is impossible to realize such boundary in the air-borne sound field, because of the non- existence of a much lighter medium than the air. In this study, the arrangement of one-quarter wave-length acoustic tubes is employed as a soft boundary. This acoustic tube has frequency dependence, but the sound pressure becomes nearly zero at the tube mouth around the odd resonance frequency. The relation between the noise reduction efficiency and this acoustically soft boundary is examined experimentally and more than 40 dB noise reduction is obtained in a one-half octave band around the first resonance frequency. It is also made clear that more than one wave length of soft boundary is required to get enough reduction compared with the reduction obtained in the case of quite a long soft boundary.

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We examined the threshold at which a camouflaged color texture pattern (target) embedded in a surrounding colored texture pattern (background) was discriminated by making the difference between their color distributions serve as a cue. The texture consisted of 900 colored disks. The color applied to the disk was chosen from a normal distribution with the mean and the standard deviation set beforehand. The mean of the background's distribution was a standard achromatic color set at L*=40, u*=0, and v*=0 of CIELUV. In experiment 1, the mean of the target's color distribution was shifted from the background's one. The threshold for the mean of the target's color distribution depended on the standard deviation and increased as the standard deviation became bigger. In experiment 2, the standard deviation of the target's color distribution was shifted. There was the slight dependence of threshold of the standard deviation of the target's distribution on that of the background's distribution. In experiment 3, both of the mean and the standard deviation of the target's color distribution were shifted at the same time. The threshold was not determined by each of the mean and the standard deviation independently. There seemed to be some compensating contribution between them to each other. The threshold could be characterized by Doyle metric or modified Doyle metric.

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Temporal aspects of the perceptual integration of audiovisual information were investigated by utilizing the visual ‘streaming-bouncing’ phenomenon. When two identical visual objects move towards each other, coincide, and then move away from each other, the objects can either be seen as streaming past one another or bouncing off each other. Although the streaming percept is dominant, the bouncing percept can be induced by presenting an auditory stimulus during the visual coincidence of the moving objects. Here we show that the bounce-inducing effect of the auditory stimulus is paramount when its onset and offset occur in temporal proximity of the onset and offset of the period of visual coincidence of the moving objects. When the duration of the auditory stimulus exceeded this period, visual bouncing disappears. Implications for a temporal window of audiovisual integration and the design of effective audiovisual warning signals are discussed.

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Recent development of sound reproduction systems such as 5.1 surround produces artificial sound field inside the enclosure. The acoustic characteristic of the enclosure is an important factor which determines the quality of the sound field reproduction. This paper provides a useful method for evaluating the characteristics of the sound field in the enclosed space. The proposed method is based on the visualization of the measured sound intensity. In this research, the sound intensity is obtained by measuring the impulse responses from the sound source to the receiving points. The direction and the strength of the intensity can be interpreted as having a strong correlation with the reflected sound from the corresponding direction. The proposed method thus projects that information, i.e., the arriving direction and the strength of the intensity, as the circle having appropriate radius onto the surface of the rectangular wire-frame box. This visualization makes it easy to grasp the fundamental characteristics of the reflections in the enclosure.

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Some hearing-impaired persons with hearing aids complain of listening difficulty under reverberation. No method, however, is currently available for hearing aid fitting that permits evaluation of hearing difficulty caused by reverberations. In this study, we produced speech materials with a reverberation time of 2.02 s that mimicked a reverberant environment (a classroom). Speech materials with reverberation times of 0 and 1.01 s were also made. Listening tests were performed with these materials in hearing-impaired subjects and normal-hearing subjects in a soundproof booth. Listening tests were also done in a classroom. Our results showed that speech material with a reverberation time of 2.02 s had a decreased listening-test score in hearing-impaired subjects with both monaural and binaural hearing aids. Similar results were obtained in a reverberant environment. Our findings suggest the validity of using speech materials with different reverberation times to predict the listening performance under reverberation of hearing-impaired persons with hearing aids.

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It is argued that knowledge of cognitive psychology, and hence also of sensation and perception, one of its branches, is indispensable when one aims at improving our artificial environment. Four examples of sensation and perception studies are described. Firstly, an experiment was discussed to design a postal code format that can be used accurately in terms of the capacity of short-term visual memory. The second example describes a perceptual conflict between visual and bodily (kinesthetic/proprioceptive) sensations that arises as a result of wrongly designing buildings. In the third example it is shown that vibrotactual displays should present frequencies that trigger the Pacinian system in the skin if people have to make quick and accurate decisions. Finally, a study of a simple acoustic orientation system that can promote indoor travel and activity by blind people was described.

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The government of Fukuoka City conducted a survey to determine the effectiveness of an audio-guidance system for the blind. The blind participants confirmed the usefulness of the audio-guidance. In addition, the blind participants and the walking instructors also provided various comments and suggestions for the better utilization of audio-guidance systems for smoother transportation. In order for the participants to be able to recognize auditory signals, it was important to be able to hear them at their peak volumes. To understand the actual meaning of announcements, however, the average volumes of the signals were more important than their peak volumes. The blind participants suggested that auditory signals and announcements should provide short and simple messages. The walking instructors provided comments regarding the placement of loudspeakers to enhance auditory localization. They recommended hanging the loudspeakers from ceilings located in front of passengers. Furthermore, the necessity of controlling excess reverberations was indicated in order to better enable blind citizens to recognize and localize the auditory signals. It was suggested that using different auditory signals for different purposes and places was effective for smoother transportation.

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The neural mechanisms for the perception of face and motion were studied using psychophysical threshold measurements, event-related potentials (ERPs), and functional magnetic resonance imaging (fMRI). A face-specific ERP component, N170, was recorded over the posterior temporal cortex. Removal of the high-spatial-frequency components of the face altered the perception of familiar faces significantly, and familiarity can facilitate the cortico-cortical processing of facial perceptions. Similarly, the high-spatial-frequency components of the face seemed to be crucial for the recognition of facial expressions. Aging and visuospatial impairments affected motion perception significantly. Two distinct components of motion ERPs, N170 and P200, were recorded over the parietal region. The former was related to horizontal motion perception while the latter reflected the perception of radial optic flow motion. The results of fMRI showed that horizontal movements of objects and radial optic flow motion were perceived differently in the V5/MT and superior parietal lobe. We conclude that an integrated approach can provide useful information on spatial and temporal processing of face and motion non-invasively.

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As information technology becomes more ubiquitous in our work and daily life environments, understanding contexts of activities becomes critical to enhance a foundation for human-centered design practice. This research introduces a conceptual framework for defining, representing and incorporating contexts as core information for interactive systems design. Modular Scenario Composition Method was developed as a mechanism for linking descriptive field study information and analytical aspect models representing many viewpoints involved in the system development and use processes. Design Information Framework (DIF) previously developed by the author was used as a common information platform to bridge different information representation formats including scenarios and aspect models. By combining modular scenarios and aspect models representing contexts, chains of relations between contexts, their triggering factors, and their influences on user actions can explicitly be described.

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This study investigated the perception of three Cantonese level tones produced by speakers with dysarthria associated with cerebral palsy. Four speakers with dysarthria were selected on the basis of their distinctive patterns of fundamental frequency (F0) values observed in the level tones they produced, which showed errors in either F0 level or, F0 contour, or both. Monosyllabic words which contrasted in tone level were used as stimuli in an identification task. Five expert listeners identified the tones among the six Cantonese contrastive tones. Results showed that the tones produced by the dysarthric speakers were predominantly perceived as level tones; although a majority was perceived as the wrong level tone. The most important finding is that only the level tones produced by dysarthric speakers could be identified as rising or falling contour tones. The frequent perceptual confusion among the level tones, and the perception of contour tones, shows that a disorder in the production of pitch-based linguistic contrasts can have a substantial impact on the communication abilities of individuals with cerebral palsy.

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This paper addresses the ways in which heat loss effector functions change with maturation and aging, using data obtained in our laboratory. Prepubertal children have an underdeveloped sweat function compared with young adults; this is compensated by a greater surface area-to-mass ratio and relatively greater heat loss from cutaneous vasodilation on the head and trunk when the air temperature is lower than the skin temperature. As the heat dissipation depends greatly on the evaporation of sweat, the core temperature of prepubertal children is greater than that of young adults owing to the underdevelopment of sweating. In the elderly the heat loss effector function decreases with aging. The decrease may first involve cutaneous vasodilation, then sweat output per gland, and finally active sweat gland density; and it may proceed from the lower limbs to the back of the upper body, the front of the upper body, then the upper limbs and finally to the head.

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In this paper, the impression of various kinds of auditory signals currently used in automobiles and a comprehensive evaluation were measured by a semantic defferential method. The desirable acoustic characteristic was examined for each type of auditory signal. Sharp sounds with dominant high-frequency components were not suitable for auditory signals in automobiles. This trend is expedient for the aged whose auditory sensitivity in the high frequency region is lower. When intermittent sounds were used, a longer OFF time was suitable. Generally, “dull (not sharp)” and “calm” sounds were appropriate for auditory signals. Furthermore, the comparison between the frequency spectrum of interior noise in automibiles and that of suitable sounds for various auditory signals indicates that the suitable sounds are not easily masked. The suitable auditory signals for various purposes is a good solution from the viewpoint of universal design.

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Using various compositions with alterations in figures' gaze directions and additions of an object, the interpretation of gaze directions and the impression of a figure were examined. The results obtained by factor analysis, cluster analysis, multi-dimensional scaling and questionnaires showed that 1) observers' impression of a figure was affected not only by figures' gaze directions but also by the presence or absence of an object viewed by figures, 2) compositions of joint attention gave a positive impression even if in an averted composition (parallel joint attention), 3) the pictures used here were viewed from the point of view of the attachment of mothers and the independence of children, and 4) a woman in this picture was evaluated from the aspect of a motherhood or pre-motherhood impression. These results are discussed in terms of the cognitive process of gaze directions as well as the developmental process of the mother–child relationship.

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In the present study, we examined the frequency dependence of auditory search performance. Detection thresholds were measured for an 800-Hz target tone in a sequence of distractor tones (informational masking) as a function of frequency separation between the target and the distractor tones. The results showed that the thresholds decreased monotonically with frequency separation increasing. To further quantify the frequency dependence of auditory search performance, we applied a roex function (Patterson and Moore, 1986) to estimate a filter bandwidth for the threshold data. The estimated bandwidth was wider than that of an auditory filter by a factor of five (Leek et al., 1991). This result, together with some earlier results (Mori, 2003), demonstrates the effectiveness of the informational masking we used.

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The effect of overlapping dynamic visual noise on visually induced self-motion perception (vection) by upward or downward optical flow was tested. The dynamic visual noise consisted of rapidly refreshed sparse random dots. Binocular disparity of the overlapping noise plane was varied. The results showed that when the noise was presented on the flow plane or on a plane farther than the flow plane, vection was totally impaired. This demonstrates that dynamic visual noise is functionally equivalent to static patterns in the vection suppression effect. A possibility of dynamic visual noise as a vection suppressor in an application on a 3-D display is discussed in relation to simulator sickness.

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It is difficult to design the Virtual Reality (VR) Environment which controls VR sickness and promotes presence. This is because the relationship between the user's susceptibility to VR sickness and a sense of presence, determined by velocity and visual angle of the visual information, involves a trade-off between the two. Then we propose the optimal value search system which computes efficiently the velocity and visual angle which control VR sickness and do not impair presence by taking account of a subject's characteristic. Under certain experimental conditions, some subjects showed serious VR sickness whose simulator sickness questionnaire total score was more than 60 and needed more than 30 minutes to recover from VR sickness. However, on the condition of angular velocity and visual angle computed by our proposed method, all subjects felt their vection, which was our index for the sense of presence, over 70 percent of their experiment time; no subject needed more than 5 minutes to recover from VR sickness.

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The main purpose of this study is to investigate the continuity of the planning of shopping malls in downtown areas of Japan and to look into the tendencies of the current existing malls until today. This paper is a summary of a survey conducted on the actual conditions of current shopping malls and a questionnaire administered to local governments in the survey areas. The results of this study allow us to summarize the reasons for and changes caused by renewal efforts directed toward the streets, public spaces, and urban elements (pavement, bench, streetlight, arcade, sculpture, etc.) in shopping malls. Furthermore, these results also help us to understand the scale of the renewal efforts as well as their timing in relation to when the shopping mall was originally constructed.

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We examined Emmert's law by measuring the perceived size of an afterimage and the perceived distance of the surface on which the afterimage was projected in actual and virtual environments. The actual environment consisted of a corridor with ample cues as to distance and depth. The virtual environment was made from the CAVE of a virtual reality system. The afterimage, disc-shaped and one degree in diameter, was produced by flashing with an electric photoflash. The observers were asked to estimate the perceived distance to surfaces located at various physical distances (1 to 24 m) by the magnitude estimation method and to estimate the perceived size of the afterimage projected on the surfaces by a matching method. The results show that the perceived size of the afterimage was directly proportional to the perceived distance in both environments; thus, Emmert's law holds in virtual as well as actual environments. We suggest that Emmert's law is a specific case of a functional principle of distance scaling by the visual system.

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The results of a survey that was carried out inside five account division workplaces of design companies in Tokyo and Fukuoka in order to identify problems concerning the personal storage system revealed that the main problem concerns how to organize the files within a desk. Firstly, there is a lack of available storage space and therefore a person couldn't work and sit well as the documents are piled up on the desktop and under the desk. Secondly, the files display within a desk is not sufficient to enable a worker to get what he/she needs easily. Hence, with purpose of overcoming the previous problems, we focused on three requirements: a) How to increase the personal storage space; b) How to display the documents well; and c) How to distribute the documents within a desk. We suggested a solution for each mentioned requirement. This study aims mainly to test the recommended solutions in order to examine their effectiveness to overcome those problems. The results of the tests that were conducted with 20 persons in a working area revealed that the files organization through the desk space has influences on the person's comfort and the time for file accessibility.

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This study provides one of very few experimental investigations into the impact of a musical soundtrack on the video gaming experience. Participants were randomly assigned to one of three experimental conditions: game-with-music, game-without-music, or music-only. After playing each of three segments of The Lord of the Rings: The Two Towers (Electronic Arts, 2002)—or, in the music-only condition, listening to the musical score that accompanies the scene—subjects responded on 21 verbal scales. Results revealed that some, but not all, of the verbal scales exhibited a statistically significant difference due to the presence of a musical score. In addition, both gender and age level were shown to be significant factors for some, but not all, of the verbal scales. Details of the specific ways in which music affects the gaming experience are provided in the body of the paper.

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Several illusory phenomena in auditory perception are accounted for by using the event construction model presented by Nakajima et al. (2000) in order to explain the gap transfer illusion. This model assumes that onsets and offsets of sounds are detected perceptually as if they were independent auditory elements. They are connected to one another according to the proximity principle to constitute auditory events. This model seems to contribute to a general cross-modal theory of perception where the idea of edge integration plays an important role. Potential directions in which we can connect the present paradigm with speech perception are indicated, and possibilities to improve artificial auditory environments are suggested.

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When we want to express the subjective impression of sound, we usually use onomatopoeias. We investigated the relationship between the impression of auditory imagery associated with Japanese onomatopoeic representation and onomatopoeic features. Subjects rated the impressions of auditory imageries associated with 40 onomatopoeias on semantic differential scales. Principal component analysis was applied to the rating data and the scales were integrated to the components of beauty, potency and sharpness. We determined the relationship between phonetic features of onomatopoeias and tonal features of the auditory imageries on the obtained principal components. Onomatopoeic representations that included voiced consonants were associated with a ‘dirty’ impression. Onomatopoeic representations that contained approximant sounds were associated with a ‘powerful’ impression. The vowel /i/ was associated with a ‘sharp’ impression and vowels /u/ and /o/ were associated with a ‘dull’ impression. The obtained tendencies confirmed that some onomatopoeic features reflected particular impressions of auditory imagery.

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