Subjective Comfort Perception Research Articles

Room acoustics of Mycelium Textiles: the Myx Sail at the Danish Design Museum

Abstract Taking the Myx Sail displayed at the Danish Design Museum as a case study, this article investigates the room acoustics of an architectural installation made of Mycelium Textiles. Mycelium Textiles represent a novel typology of mycelium-based composites (MBC). The Myx Sail absorbers are grown on a composition of different layers of plant fibres combining woven jute textile with hemp mat and loose wood wool substrate enhancing the mechanical and acoustic properties of the composite. Two complementary acoustic tests were conducted to measure the absorbing properties of the mycelium material and its effects on the acoustics of the exhibition hall. The results show that the sail acts effectively as an acoustic absorber especially in higher range of frequencies, reducing the reverberation time and improving speech intelligibility. The effect of the sail on the overall room acoustics is especially effective, if the sound source is placed directly underneath the sail. The results of a complementary survey amongst visitors on their subjective perception of comfort and well-being however indicate that the degree to which a grown surface (and by extension, a grown building) is perceived positively or negatively depends on the relationship the individual has with Nature.

Literature Review of an Anterior Deprogrammer to Determine the Centric Relation and Presentation of Cases.

The increasing demand for dental aesthetics, articulation corrections, and solutions for pain and frequent bruxism demands quick and effective restorative dental management. The biomedical research aimed to create a beneficial, ecological, and readily available anterior deprogrammer to determine the centric relation (CR) of cases. This medical device is additively manufactured from a biocompatible material. Size is customizable based on the width of the patient's anterior central incisors. This is a pilot study with two subjects. The task was to develop a complete data protocol for the production process, computer-aided design (CAD), and three-dimensional (3D) printing of the anterior deprogrammers. The research focused on creating simple and practically applicable tools for the dentist's prescription (anterior deprogrammer in three sizes), and secondly for the communication between the dentist and the patient (computer application). The tested hypothesis was whether, according to these novel tools, it is possible to produce functional occlusal splints, which could be manufactured using current technologies. This study compared a traditional splint with a digitally designed and 3D-printed one. The tested hypothesis was whether manufactured occlusal splints differ in patients' subjective perception of comfort. Each conservative treatment was monitored for ten weeks. Initial results are promising; no statistically significant difference was found between the productive technologies.

The Impact of Sound Pressure Level, Loudness, Roughness, Sharpness, Articulation Index, Hand Vibration, and Seat Vibration on Subjective Comfort Perception of Tractor Drivers

Long-term exposure to high levels of vibration and noise can have detrimental effects on the health of tractor drivers. This study aimed to evaluate the subjective comfort experienced by drivers operating large-horsepower tractors. A total of 10 tractors sourced from 5 different manufacturers were subjected to testing. The assessment encompassed three operational conditions, namely, idle, maximum torque, and rated power. Objective measurements, including A-weighted sound pressure level (A-SPL), loudness, sharpness, roughness, articulation index (AI), hand vibration, and seat vibration, were collected. Additionally, subjective comfort evaluations were carried out using a paired comparison test. To predict the subjective comfort of tractor drivers, a novel prediction model was developed by employing a simulated annealing (SA) algorithm to optimize a backpropagation neural network (BPNN). The model successfully achieved accurate predictions of subjective comfort, yielding a maximum prediction error of 4.4%. The study findings revealed that vibration had a more pronounced impact on driver comfort in environments with lower-amplitude noise, whereas high-decibel noise exerted a masking effect on vibration-induced discomfort. In conclusion, the SA-BPNN model, utilizing A-SPL, loudness, sharpness, roughness, AI, hand vibration, and seat vibration as objective parameters, effectively predicted the subjective comfort of tractor drivers. This discovery holds significant implications for tractor manufacturers, who can employ the model to optimize the design of tractor cabs and enhance driver comfort.

Surface Electromyography of the Trapezius and Sternocleidomastoid during Computer Work with Presbyopic Corrections.

During computer work in controlled laboratory conditions, wearing multifocal contact lenses (MFCLs) showed no lower muscle load but increased subjective perception of comfort with equivalent visual quality and comparable tolerance. Because musculoskeletal complaints are frequent among computer workers, this study used the muscle electrophysiological activity of shoulder and neck muscles in presbyopic computer workers who received either progressive addition lenses for general purpose (GP-PALs) or MFCLs. For this crossover study, 11 presbyopic computer workers aged 55 ± 4 years (mean ± standard deviation) were equipped with GP-PALs and MFCLs in a randomized order. Surface electromyography signals were recorded bilaterally from shoulder and neck muscles during short-term computer work tasks using an optimally adjusted visual display unit workplace. The amplitude probability distribution function, the number and total duration of EMG gaps, and sustained low-level muscle activity periods of the surface electromyography signals were calculated. Comfort and correction type preferences were assessed. Head inclination was objectively evaluated. Multifocal contact lenses elicited no significant lower muscle load than GP-PALs. The number of sustained low-level muscle activity periods longer than 60 seconds was similar between visual aids. The total amount of gaps was significantly higher with MFCLs (44 gaps) compared with progressive addition lenses for general purpose (15 gaps) in all analyzed periods for all participants. However, there were no significant differences for the median in the intraindividual comparisons (P = .22, dz = 0.52). Multifocal contact lenses scored statistically significant higher in comfort values with equivalent visual quality and comparable tolerance (P = .003, dz = 1.51). Although the study failed to show clear results, wearing MFCLs seems to enhance working comfort compared with GP-PALs subjectively.

Comfort Evaluation of an Aircraft Cabin System Employing a Hybrid Model

Comfort is becoming one of the most important principles in the process of design and evaluation of civil aircraft cabins. However, the comprehensive quantitative evaluation of comfort in an aircraft cabin is a complicated issue because of the subjectivity of comfort perception and a large number of factors involved in the whole complex cabin system. A hybrid model combined with the Decision Making Trial and Evaluation Laboratory (DEMATEL) method and fuzzy comprehensive evaluation is proposed, which considers both the interrelation between the criteria and the fuzziness of subjective comfort perception concurrently. The result of the empirical study from the questionnaire survey in flight was consistent with that of the hybrid model. The proposed model is effective. It could provide a more reasonable priority to improve comfort in the aircraft cabin. According to the measured results of the cabin environment, the cabin facilities and layout, seats and service, the specific differences between the criteria can be displayed clearly, which is helpful to improve the cabin comfort level.

Influence of heel design on lower extremity biomechanics and comfort perception in overground running

ABSTRACT The study investigated whether an alteration of the shoe heel curvature would influence lower extremity biomechanics and comfort perception in running. Twenty recreational habitual rearfoot strikers performed five running trials in running shoes with three different heel curvature designs (short-parallel, long-parallel and oblique curvatures). Synchronised force plate and motion capturing systems were used to collect three-dimensional lower extremity joint kinetics and kinematics, followed by subjective comfort perception on the 15 cm Visual Analogue Scale. The results showed that participants wearing oblique and long-parallel curvature shoes exhibited larger initial frontal shoe-ground angle (p= 0.003, p= 0.016) and ankle inversion angle (p= 0.008, p= 0.032) as well as higher maximum sagittal foot slap velocity (p= 0.041, p = 0.011) compared with a short-parallel curvature shoe. When wearing the short-parallel curvature shoe, participants had better rearfoot stability perception than the oblique curvature shoes (p = 0.028). These results suggest that the short parallel curvature shoes had better motion control and stability perception than the other two curvature conditions. However, the design of heel curvature seems to have minimal influence on the cushioning related variables in running.

A time-series based framework for exploring the unknown effects of shoe comfort-induced biomechanical adaptations

Footwear Science struggles at identifying the unknown effects of footwear interventions on the biomechanics of running. Those struggles may partly be explained by methodological and statistical issues, such as using discrete parameters to reduce the dimensionality of time series data or testing against unspecific null hypotheses. This paper evaluates a method to address some of these deficits by applying a time series-based machine learning approach (k-nearest neighbour classification (kNN), Euclidean distance). As an example, we used a data set containing a largely unknown footwear effect: The relationship between subjective comfort and the rollover movement during running. For this purpose, we collected kinematic data and subjective ratings from 22 runners running two times each in both their most comfortable and uncomfortable shoe selected from a pool of different neutral running shoes. The kNN algorithm performed highly accurately in distinguishing between the kinematics of different shoes. We also found that larger differences in subjective comfort perception between two shoes were associated with higher classification rates. The kNN method, however, does not allow for conclusions to be drawn about the causality or quality of the observed changes within the kinematic trajectories. Accordingly, we see the main scope of the presented method primarily in exploring complex data sets in cases where no meaningful hypothesis about the presumed biomechanical effects can be derived a priori. The subsequently acquired knowledge may be used to design larger-scale studies in which these findings can be investigated more systematically by means of more specific hypotheses and better estimates of sample sizes, respectively.

Randomised controlled trial of corneal vs. scleral rigid gas permeable contact lenses for keratoconus and other ectatic corneal disorders

PurposeTo compare the comfort and visual performance of corneal rigid gas permeable contact lenses (CoL) and scleral rigid gas permeable contact lenses (SL) in participants with corneal ectasia, successfully wearing “habitual” CoL. MethodsIn a randomised controlled trial (RCT) with a 2 × 2 crossover, 34 participants were recruited and randomised into two groups. Group 1 (sequence AB), were fitted in period 1, with new CoL and after a 4-week washout period, in which habitual CoL were worn, were fitted with and crossed-over to SL, period 2. Group 2 (sequence BA), were first fitted with SL in period 1 and after a washout period of 4 weeks, crossed-over to new CoL, period 2. The median lengths in weeks of Periods 1 and 2 were: 17.5 (IQR 12.4) and 14.5 (IQR 6.2) respectively. The outcome measures for visual performance were best corrected visual acuity and the contrast sensitivity function. Vision related quality of life (Qol) was assessed using the National Eye Institute Visual Function Questioannaire-25 and reported subjective perception of vision (SPV) and reported subjective perception of comfort (SPC) scores, recorded on a scale from 1–10. The final outcome measure was the selection of the preferred lens type at the completion of the RCT. ResultsFor the 30 who completed the trial, significantly higher SPC scores were found for SL compared to CoL (p = 0.002). Significantly higher SPC scores for CoL were found in participants who selected CoL as their preferred lens for future use, compared to those who selected SL (p = 0.009). All other outcomes exhibited no significant difference between the experimental lenses. There was no significant difference (p=0.86) in the proportion preferring CoL (53%) and SL (47%). ConclusionSignificantly better comfort was reported for SL compared with CoL. Significantly higher comfort in CoL was found in those who preferred CoL, than those who preferred SL. Successful CoL wearers whose SPC in CoL is <7 are likely to achieve better comfort with SL. On average, successful CoL wearers found SL more comfortable and there are unlikely to be any significant visual or visual Qol advantage or disadvantage in refitting successful CoL wearers with keratoconus and other corneal ectasia disorders, with SL and vice versa.

Shape optimization of screwdriver handle for improving grasping comfort of precision and power grips

AbstractImproving grasping comfort is a significant factor in enhancing the value of industrial products, as most products are handled by human hands. Our aim was to optimize hand tool shapes and maximize grasping comfort, considering multiple‐shape parameters and grasping types. A screwdriver handle was used as the reference tool for this case study. The measurements of handle length, end diameter, and middle diameter were utilized as the shape parameters of the handle. Twelve participants were included in this study. We measured the participants' subjective perceptions of comfort while grasping the precision and power grips during screw‐driving and screw‐tightening tasks, respectively. The design of the screwdriver handle was formulated as a bi‐objective optimization problem with respect to the grasping comfort of the precision and power grips. A Pareto frontier was determined by optimizing the formulated problem. Well‐balanced and optimal shapes for the precision and power grips were identified.

Identifying and analyzing critical factors impacting on passenger comfort employing a hybrid model

AbstractWith the increase in air travel, comfort is becoming an important issue with which airlines differentiate themselves in a competitive market. Passengers are paying more attention to their comfort experience during flights. However, passenger comfort is affected by various factors that result from the complex cabin system. Besides, the factors have interrelations between one another. How to identify the key factors and comb through their interrelations to improve passenger comfort efficiently is a critical problem in cabin design. To solve this problem, a hybrid model is proposed to identify the key factors and discuss the interrelation between them based on the questionnaire data. First, factor analysis is conducted to segment complex influencing factors into groups and to extract the most important factors. Decision Making Trial and Evaluation Laboratory (DEMATEL) method and fuzzy set theory are combined in the next analysis, considering both the interrelation between factors and the fuzziness of subjective comfort perception concurrently. It forms a structural model and then visualizes the causal relationships among factors through a causal diagram. The results of an empirical study show that the proposed model is capable of identifying the critical factors that affect passenger comfort effectively and could offer a priority of factors to improve passenger comfort.

Human responses to the air relative humidity ramps: A chamber study

Passengers often experience ramped relative humidity (RH) in an aircraft cabin environment during the stages of climb and descent as the flight altitude changes gradually. This may affect passengers' comfort and their assessment of the environment. In this study, a series of simulated experiments are conducted in a climate chamber to investigate the effect of RH ramps on cabin passenger's comfort from takeoff until landing. Six combinations of three temperatures (20 °C, 25 °C and 28 °C) and two RH ramps conditions (50 → 20→50% RH and 80 → 20→80% RH) were set in the experiments. During the experiments, subjective comfort perceptions were tested using questionnaires and the skin temperature was also measured. The micro-climate between the skin surface and the inner clothes was also measured for body heat transfer analysis. The results have demonstrated that the RH ramps have significant effect on subjective comfort perception which is more prominent at 28 °C, 80 → 20→80% RH. In general, the thermal sensation has a good linear relationship with the standard effective temperature (SET*) and the skin temperature. However, the skin temperature is directly related to the direction of RH ramps and the environmental conditions. The heat transfer analysis has shown that the ramped RH can affect the human heat storage and can change the skin temperature mainly by affecting the human evaporative heat loss. The moisture absorption and desorption in the clothing layer significantly affect the heat transfer from human body.

The analysis of microclimate parameters in the classrooms located in different climate zones

The paper discusses issues related to indoor environmental comfort in school buildings and presents the results of research conducted in two different climate localizations: Białystok (Poland) and Belmez/Córdoba (Spain) in similar microclimate conditions. Measurements of comfort parameters were performed in university classrooms of these countries. The measurements included main thermal comfort parameters: temperature and relative humidity. Moreover other parameters that can influence the comfort perception were recorded, as the noise level, the duration of lectures or students’ density. A methodology based on surveys about indoor microclimate filled by students of these universities was developed. The results were related with subjective comfort perception. Most students in Białystok felt that the room temperature during the measurements was suitable, whereas in Córdoba in most cases it was judged as cold or too cold, even if the indoor temperature was in the recommended range and about 2K higher than in Poland. The optimal temperature of indoor air for students in Poland was 21.7–22.3°C, while in Spain 23.3–24.8°C. The majority of students (74% in Poland and 89% in Spain) found humidity as acceptable but the degree of satisfaction is higher in Poland, even when its humidity was 30% lower than monthly average relative humidity in this country. The percentage of comfort satisfaction was decreasing during the class time, while values of indoor environmental factors, as temperature or humidity, had not so important variation. Some other parameters could influence students fettle for instance: the length of lectures or the noise level. The results allowed to estimate preferable ranges of indoor environment for both countries, note differences in students opinions about similar microclimate. This information can included in the respective national rules for educational buildings.

Effects of functional shirts with different fiber compositions on thermoregulation in well-trained runners

This study aimed to investigate the effects of two functional sport shirts with different fiber compositions (polyester: 100% polyester vs polyester–lyocell combination: 67%–33%) on thermoregulation and wearing comfort during treadmill walking at an average intensity under moderate environmental conditions. It was hypothesized that the hydrophilic lyocell fibers would benefit sweat evaporation and, thus, provide a superior cooling effect. Using a repeated-measures study design, core, surface and between skin-and-shirt temperatures were measured in 11 men while wearing either the polyester or polyester–lyocell shirt. Additionally, sweat loss, heart rate and subjective perception of comfort were determined. In spite of significantly greater sweat production, relative humidity was lower with the polyester–lyocell shirt. In the later phases of the walking intervention, the temperatures were consistently higher with polyester–lyocell, although between-shirt differences failed to reach significance. These results suggest that greater water retention limits the thermoregulatory efficiency of cellulosic fibers when excessive sweat production occurs.

Postural sway and perceived comfort in pointing tasks

In this study, we explored relations between indices of postural sway and perceived comfort during pointing postures performed by standing participants. The participants stood on a force plate, grasped a pointer with the dominant (right) hand, and pointed to targets located at four positions and at two distances from the body. We quantified postural sway over 60-s intervals at each pointing posture, and found no effects of target location or distance on postural sway indices. In contrast, comfort ratings correlated significantly with indices of one of the sway components, trembling. Our observations support the hypothesis that rambling and trembling sway components involve different neurophysiological mechanisms. They also suggest that subjective perception of comfort may be more important than the actual posture for postural sway.

Pressure and comfort perception in the system “female body–dress”

Abstract The three-dimensional (3D) Garment virtual technology is expected to help the designers to turn own trends and ideas into the creative samples more quickly with 3D simulation and the visualization of the pressure values and stress points where the fabric might be too tight against the body. The aim of this study is to present the wearer perceptions of woven fabric in 22 anthropometrical points located on the women torso, which can then be helpful to accurately predict the ease and tightness of a garment in 3D Garment virtual try-on system. For establishing the common principles joining the eases value designed on pattern block and the pressure perception in the system “body–dress”, we took the experiment with the women using Flexiforce Sensor® and ELF® system concerning the woman dresses with sleeve-in as the basic garment category. The objective pressure measured on seven levels of woman torso wearing the dresses designed by different ease distribution. All points and levels of the pressure measuring reflected to the daily movements, and the results obtained were compared with the corresponding subjective comfort perception from the wearer. The relationship between the ease values designed on 2D pattern and the pressure perception from the wearer were analysed to supply the theoretical reference for 3D virtual try-on system improvement.

Cushion Surface Modeling Based on Body Pressure Distribution and Subjective Rating

This paper presents a method of ergonomic design based on subjective rating for the purpose of modeling cushion surface mapped by body pressure distribution (BPD) test data. A sitting comfort evaluation scale was designed to collect subjective comfort perception. Optimal BPD test data were selected by comparing comfort rating after experiments on a trial seat. A data mapping model was established between point clouds in three dimensional coordinate and BPD test data, which can be recognized and transferred in CAD system. In this context, an ergonomic-aided system was developed in practical application to demonstrate the viability of the method. Two designers tried out the system to design a seat cushion, and compared it with conventional method in Rhino software. Results show that the system is more interactive to designers, which can save time of surface modeling by about 50%.

파지 폭과 손 크기에 따른 각 손가락이 총 악력에 미치는 영향 분석

In this study, six grip spans (45㎜~65㎜) were tested to evaluate the effects of handle grip span and user's hand size on maximum grip strength, individual finger force, and subjective ratings of comfort using a digital dynamometer with individual force sensors. Forty-six males were assigned into three hand size groups according to their hand lengths. Results showed that overall 55㎜ and 50㎜ grip spans were the most comfortable sizes and associated with the highest grip strength in the maximum grip force exertions, whereas 65㎜ grip span was rated as the least comfortable size as well as the lowest grip strength. In the interaction effect of grip span and hand size, small and middle hand sized participants rated the best preference and the least preference grip spans differently with large hand sized participants. With respect to the analysis of individual finger force, the middle finger force was the strongest and the highest contribution to the total finger force, followed by ring, index and little fingers. In addition, it was noted that each finger had a different optimal grip span for exerting maximum force resulting in a bowed contoured shaped handle for two-handle hand tools. Thus, the grip spans for two-handle hand tools might be designed according to the users' hand and finger anthropometrics to maximize performance and subjective perception of comfort.

Influence of Heel Height and Shoe Insert on Comfort Perception and Biomechanical Performance of Young Female Adults During Walking

The possible negative effects of high-heeled shoes on subjective comfort perception and objective biomechanical assessment have been noted. Although shoe inserts have been widely applied in footwear to increase comfort and to reduce the frequency of movement-related injury, no study has attempted to identify insert effectiveness in high heels. The purpose of this study was to determine the effects of heel height and shoe inserts on comfort and biomechanics as represented by plantar pressure and ground reaction force (GRF). Twenty young female adults performed the test conditions formed by the cross-matching of shoe inserts (shoe without insert and shoe with total contact insert [TCI]) and heel height (a flat, a low heel [3.8 cm] and a high heel [7.6 cm]). Two-way analyses of variance for repeated measures design were used to test condition effects on comfort rating, plantar pressure, and GRF during gait. To determine the biomechanical variables that can predict comfort, a multiple linear regression with stepwise method was done. The results showed that discomfort increased with heel height. In high heels, the plantar pressure in the heel and midfoot shifted to the medial forefoot, and the vertical and anteroposterior GRF increased. Use of the TCI reduced the peak pressure in the medial forefoot. Interestingly, the effectiveness of the TCI was greater in the higher heels than in the lower heels and in flat heels. The peak pressure in the medial forefoot, impact force, and the first peak vertical GRF could explain 75.6% of the variance of comfort in high-heeled gait. These findings suggest that higher heels result in decreased comfort, which can be reflected by both the subjective rating scale and biomechanical variables. Use of a TCI altered the biomechanics and therefore improved the comfort in high-heeled shoes.

Ergonomics modelling and evaluation of automobile seat comfort

Automobile seats are developed in an iterative manner because subjective feedback, which is usually of questionable quality, drives the design. The time and cost associated with iteration could be justified if the process was guaranteed to produce a comfortable seat. Unfortunately, this is not the case. Current practices are based on the premise that seat system design teams need objective, measurable laboratory standards, which can be linked to subjective perceptions of comfort. Only in this way can predictions be made regarding whether or not a particular design will be viewed by the consumer as comfortable. This type of forecasting ability would effectively improve the efficiency with which automobile seats are designed. In this context, the research reported, developed, and validated a stepwise, multiple linear regression model relating seat interface pressure characteristics, occupant anthropometry, occupant demographics, and perceptions of seat appearance to an overall, subjective comfort index derived from a survey with proven levels of reliability and validity. The model performance statistics were: adjusted r 2 = 0.668, standard error of estimate = 2.308, F (6, 38) = 15.728, p = 0.000, and cross-validated r (15) = 0.952, p = 0.000. From the model, human criteria for seat interface pressure measures were established. These findings could not have been attained without first demonstrating that (1) the data collection protocol for seat interface pressure measurement was repeatable and (2) seat interface pressure measurements can be used to distinguish between seats.

Biomechanical evaluation of the comfort of automobile clutch pedal operation

The objective of the present study is to investigate not only the subjective comfort perception of clutch pedal operation, but also possible correlations between subjective rating and biomechanical parameters such as joint angle, moment and work for a better understanding of discomfort. The influence of four main design parameters of clutch pedal (seat height, pedal travel, pedal travel inclination, pedal resistance) was studied using a multi-adjustable experimental driving package. Fifteen subjects participated in the experiment. They were five short females, five average-height males and five tall males. Comfort was evaluated using a general comfort rating scale. The relationship between comfort rating and biomechanical parameters was explored. Globally, the results from the biomechanical evaluation of comfort/discomfort are consistent with those from the subjective evaluation. Both agree with the principle of minimum work, observed in biomechanical analysis of leg movements. This is characterized by the preference of not raising the leg during the approach phase, and the preference of low joint work at the knee and hip during the depression phase. Practical recommendations of clutch pedal design are discussed and suggested. Relevance to industry The results of the present study can aid ergonomists in understanding the discomfort caused by foot control operations as well as in the design of pedal controls.