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For data augmentation of the pneumonia diagnosis algorithm by deep learning, an image conversion method through a convolutional method utilizing spatial impulse and sound quality factors of cough sounds is proposed. First, reverberant spaces with different volumes were implemented, and spatial impulse responses were generated for each space through computer simulation of spatial models according to sound source and receiver points. Sound quality analysis was performed to improve accuracy, and 2-D sound quality data of time series was converted into 3-D image data using the Gramian Angular Field (GAF) method for combination between heterogeneous data. As a result, 97.5% accuracy was obtained for the configured dataset. The result of this study is expected to be used to develop diagnostic algorithms for various respiratory diseases including pneumonia in the future.

Electric and autonomous vehicles have brought about a paradigm shift in interior space design and are now replacing their functions as spaces for living, work and leisure activities. Therefore, in order to design the optimal sound environment for the interior space of the vehicle, it is necessary to investigate the interior soundscape of the vehicle based on the type of occupant's activity and the purpose and function of the space. However, although the soundscape concept has been applied to the design of urban and natural spaces and large indoor spaces such as open plan offices, there is no study on the interior space of vehicles. In this study, soundscape indicators were set according to the activity patterns of autonomous vehicle occupants. Through the result, it is possible to derive vehicle interior soundscape design factors based on the evaluation of each type of sound environment presented.

This study investigated the effects of psychophysiological restoration due to environmental factors while experiencing the city, waterfront, and green space using various psychological scales and physiological measurement tools. The environment was experienced using virtual reality technology, and the subjects' responses were collected through surveys and EEG (electroencephalography) and HRV (heart rate variability) measurement. HRV responses were carried out by parameters such as total power (TP), SDNN and TSI. In case of EEG, PSD (power spectrum density) analysis indicated a relatively high restoration effect in the natural environment and increase of alpha-beta ratio. Based on functional connectivity, graph theory analysis showed that the limbic system network of non-restoration group was hyperactive. When comparing HRV responses (increase of TP, SDNN and reduction of TSI), from the resilience group, it was found to have higher global network efficiency. In fact, in urban space, there were fewer psychological restoration responses in the group with high noise sensitivity.

Experiments were performed to identify the mechanism of heavyweight floor impact sound transmission through floors in a high-rise apartment building. Vibration and sound levels on each floor of the multistory building were measured. The vibration generated at a given floor was transferred to multiple adjacent floors with decreasing amplitudes proportional to the distance from the excited floor. This vibration transfer introduced significant sound transmissions. The structural static load varied depending on the floor location due to differences in the weight of the structure above the floor, especially for wall construction buildings. The static load at the wall of the bottom floor was the largest among the different floors. The influence of this static load on the impact sound generation was investigated through tests in the actual building and the scale model, respectively. The results were numerically analyzed using the spectral element method. With the increasing static load, the resonance frequencies of the floor increased due to the change in the vibration modes of the structure. The modulated sound generation from the floor vibrations transmitted to multiple layers with larger magnitudes due to this static load.

A 1:10 scale of a street canyon and courtyard was constructed to evaluate sound propagation when various vegetation treatments including trees, shrubs, vegetated facades, and green roofs were installed in the urban environment. Noise reductions in the street canyon and courtyard were measured for both single and combined vegetation treatments. Vegetated facades mitigated the overall noise level up to 1.6 dBA in the street canyon, and greening facades were effective to reduce low frequency noise levels below 1 kHz. Trees increased the noise level at high frequency bands to some extent in the street canyon, while the noise level over 1 kHz decreased in the courtyard after installing the street trees. This is because tree crowns diffused and reflected high frequency sounds into the street canyon. Green roofs offered significant noise abatement over 1 kHz in the courtyard, while the vegetated facade was effective to reduce noise levels at low frequencies. In terms of the integrated effects of vegetation treatments, a combined vegetation treatment was less effective than the sum of single treatments in the street canyon. The maximum noise reduction observed for all combinations of vegetation treatments provided 3.4 dBA of insertion loss in the courtyard.

It is necessary to consider not only annoyance of interior noises but also speech privacy to achieve acoustic comfort in a passenger car of a high-speed train because speech from other passengers can be annoying. This study aimed to explore an optimal acoustic environment to satisfy speech privacy and reduce annoyance in a passenger car. Two experiments were conducted using speech sources and compartment noise of a high speed train with varying speech-to-noise ratios (SNRA) and background noise levels (BNL). Speech intelligibility was tested in experiment I, and in experiment II, perceived speech privacy, annoyance, and acoustic comfort of combined sounds with speech and background noise were assessed. The results show that speech privacy and annoyance were significantly influenced by the SNRA. In particular, the acoustic comfort was evaluated as acceptable when the SNRA was less than -6 dB for both speech privacy and noise annoyance. In addition, annoyance increased significantly as the BNL exceeded 63 dBA, whereas the effect of the background-noise level on the speech privacy was not significant. These findings suggest that an optimal level of interior noise in a passenger car might exist between 59 and 63 dBA, taking normal speech levels into account.

This study investigated the potential restorative effect of various urban soundscape experiences. The evaluation stimulus was implemented using virtual reality technology in a laboratory environment. Restoration-related semantic expression words were selected from the interview responses of 50 subjects, and the presence or absence of the expression of the words was newly proposed as a restorative potential criteria. The objective characteristics of urban soundscapes were analyzed based on auditory, visual, and object aspects, and subjects responded to sound source identification, perceived affective quality, and overall quality. The temperament and character inventory-revised short version and satisfaction with life scale were used to investigate individual characteristics. Based on this, a prediction model having an accuracy of 83% was proposed for the restorative potential criteria. As a result, it was found that the overall perception of soundscape was a crucial factor in increasing the restorative potential effect of the urban soundscape experience. In addition, it was confirmed that the restorative potential effect by individual characteristics varied significantly even in the same space. The findings of this study are expected to serve as a basis for sustainable and healthy urban soundscape design.

In this study, the restorative effect of a natural environment experience simulated with interactive virtual reality technology on the psychophysiological response was investigated. Three simulated virtual reality stimuli were selected: a green-dominated area, green and water combined area, and water-dominated area. Free movement was permitted to provide interaction in virtual reality, and an appropriate sound environment was provided in real time to each space through 3-D sound technology. Fifty subjects experiencing the normal levels of stress or depression participated in this study. The aim was to locate the most restorative point in the natural environment, and the physical properties at each point were quantified. In addition, to collect psychological responses, subjects were asked to respond to a restoration questionnaire based on the attention restoration and stress reduction theory and a questionnaire on soundscape and landscape perception. Concurrently, various physiological responses, such as heart rate, electroencephalogram, and eye tracking, were measured. Finally, the relationship between physical characteristics and psychophysiological responses was investigated. Based on this, guidelines were presented on how to create a virtual reality natural environment for stress recovery.

In the present study, the vibration characteristics of floating floor systems and the discomfort in walking upon them have been studied in concrete slab structures through mock-up floors experiments. Seven types of floor systems, with panels of various sizes and supporting beams with different joist spacings, were constructed based on actual conditions. For the vibration measurement, an ISO rubber ball dropped from a height of 20 cm was used as an impact source to reproduce human walking. The vibration characteristics were evaluated by calculating the vibration acceleration values and the autocorrelation function parameters for the floor structures. Finally, a human walking experiment was conducted to investigate subjective responses to the vibration characteristics of floating floors. From the results, it was found that the vibration acceleration values and walking discomfort varied with the supporting conditions of the floors and that these were highly correlated with each other. It was also found that more than 75% of subjects accepted the floors when the vibration value of the floor in terms of vibration does value (VDV) is below 4.8 ms(-1.75). In addition, a practical regression of the VDV was obtained and design guidelines for floating floors were suggested.

Religious precincts in urban spaces have their own religious spatiality formed by their sociocultural and historical background. It is necessary to identify the spatiality of urban religious precincts in their sociocultural contexts because soundscape perception is determined largely by context. In the present study, social surveys and soundwalks were performed in a Catholic cathedral and in Buddhist temple precincts in Seoul. In the surveys, important spatial functions, sound, and visual components of the Catholic cathedral and Buddhist temple precincts were investigated by principal component analysis. The results showed that the cathedral precincts play a more important role in social functions related to mainly visual components than the temple precincts do, whereas the functions for religious activities related to sound elements are more stressed in the temple precincts. In the soundwalk evaluation, contributions of soundscape and landscape components to tranquility in the two religious precincts were explored. It was found that pleasantness of soundscape and attractiveness of landscape significantly affected the perception of tranquility. In addition, it was revealed that a sense of enclosure could enhance tranquility in urban religious precincts.

A Swedish soundscape quality protocol was developed and has been used as a representative soundscape-quality assessment method around Europe. However, this protocol has limitations in Asian countries because the countries have distinctly different social and cultural backgrounds and form their own unique soundscapes. Consequently, this study examined the utility of a soundscape assessment survey for Koreans by comparing unconstrained natural-language expressions and existing protocol survey questions. To this end, soundscape data from a variety of places, e.g., parks, tourist attractions, and commercial areas in Seoul, Korea, were collected using 360-deg cameras and Soundfield microphones. In addition, a virtual-reality (VR) assessment environment was constructed using a head-mounted device (HMD) and 3-D audio technology under laboratory conditions, and the collected soundscapes were assessed. The participants were encouraged to freely and verbally express their thoughts about the sound environment of each place, and text data were obtained through voice-recognition technology. The protocol survey was conducted for the same subjects after the assessment. The results showed that it is necessary to develop a soundscape assessment standard that is appropriate for Koreans because differences from the existing European-style soundscape protocol were revealed in the assessment items, when an emotional analysis was conducted using text-mining technology.

The present study investigates the cognitive performance and subjective perceptions in the context of road traffic noise alone and multiple noises, including construction and ventilation noises. A total of 20 university students were exposed to seven noise conditions. Laboratory experiments employed semantic and episodic memory tasks. Self-reports of perception were collected from the participants. It was found that multiple noise sources impaired the free recall of words, and free recall scores were affected by noise type. Significant differences in free recall scores were found when the noise level difference between the individual noise and multiple noise sources was more than 5 dB. In contrast, word comprehension did not mediate the effects of noise on semantic memory. Annoyance caused by multiple noise sources correlated highly with the results of the free recall and word comprehension tasks. Moreover, loudness and roughness were found to account for the annoyance ratings of combinations of road traffic noise with construction or ventilation noises.

In musical or theatrical performance, some venues allow listeners to individually localize and segregate individual performers, while others produce a well blended ensemble sound. The room acoustic conditions that make this possible, and the psycho-acoustic effects at work are not fully understood. This research utilizes auralizations from measured and simulated performance venues to investigate spatial discrimination of multiple acoustic sources in rooms. Signals were generated from measurements taken in a small theater, and listeners in the audience area were asked to distinguish pairs of speech sources on stage with various spatial separations. This experiment was repeated with the proscenium splay walls treated to be flat, diffusive, or absorptive. Similar experiments were conducted in a simulated hall, utilizing 11 early reflections with various characteristics, and measured late reverberation. The experiments reveal that discriminating the lateral arrangement of two sources is possible at narrower separation angles when reflections come from flat or absorptive rather than diffusive surfaces.

The aim of this study is to investigate the effects of both room acoustic conditions and spectral characteristics of noises on acoustic discomfort in a high-speed train's passenger car. Measurement of interior noises in a high-speed train was performed when the train was operating at speeds of 100 km/h and 300 km/h. Acoustic discomfort caused by interior noises was evaluated by paired comparison methods based on the variation of reverberation time (RT) in a passenger car and the spectral differences in interior noises. The effect of RT on acoustic discomfort was not significant, whereas acoustic discomfort significantly varied depending on spectral differences in noise. Acoustic discomfort increased with increment of the sound pressure level (SPL) ratio at high frequencies, and variation in high-frequency noise components were described using sharpness. Just noticeable differences of SPL with low- and high-frequency components were determined to be 3.7 and 2.9 dB, respectively. This indicates that subjects were more sensitive to differences in SPLs at the high-frequency range than differences at the low-frequency range. These results support that, for interior noises, reduction in SPLs at high frequencies would significantly contribute to improved acoustic quality in passenger cars of high-speed trains.

In the present study, the effects of interference from combined noises on speech transmission were investigated in a simulated open public space. Sound fields for dominant noises were predicted using a typical urban square model surrounded by buildings. Then road traffic noise and two types of construction noises, corresponding to stationary and impulsive noises, were selected as background noises. Listening tests were performed on a group of adults, and the quality of speech transmission was evaluated using listening difficulty as well as intelligibility scores. During the listening tests, two factors that affect speech transmission performance were considered: (1) temporal characteristics of construction noise (stationary or impulsive) and (2) the levels of the construction and road traffic noises. The results indicated that word intelligibility scores and listening difficulty ratings were affected by the temporal characteristics of construction noise due to fluctuations in the background noise level. It was also observed that listening difficulty is unable to describe the speech transmission in noisy open public spaces showing larger variation than did word intelligibility scores.

This study proposed a design process for diffusion walls of the Art Center Incheon concert hall by using scale models and verified the sound diffusion performance in comparison with acoustic parameters. Locations of diffusers and main diffusing surfaces were determined in a 1:50 scale model, and the heights of diffusers in the stage were set and diffusion rates were evaluated according to occupancy density in a 1:25 scale model. A 1:10 scale model enabled the real acoustic characteristics of the concert hall to be evaluated. This model was used to measure scattering/diffusion coefficients of diffusers in each part and to design the finishing shapes of walls. Horizontal diffusers with the highest protrusion were installed on the lateral walls near the stage in order to orientate scattered reflections. Impulse responses were used to investigate acoustic parameters like RT, EDT, G, and C80, and the number of peak reflection (Np) was calculated to compare diffusion performance. It turned out that, when the amount of diffusion changed, the value of Np increased but the values of RT, EDT, and G and the corresponding relative standard deviation (RSD) decreased. The ratio of 1:25 or higher scale models were efficient in designing the diffusion surfaces of the concert hall. The effectiveness of scale models was verified as the directions, locations, protrusion heights, and areas of diffusers were determined.

This study assessed annoyance response to temporal variations of sound energy of heavy floor impact in apartment buildings by using a virtual reality environment. As for a real moving sound source, the noise of a child running diagonally on the floor was reproduced by applying HRTF to the sound source of a single impact ball. Annoyance was assessed in the acoustic environment where visual information was provided by using HMD and directional information was given by using HRTF. A comparison scale using the equal-appearing interval (EQI) was adopted to reflect the sense of daily life. As a result, when visual information was provided in the VR environment, the annoyance of subjects decreased. On the other hand, directional information was given, the subjects became more sensitive to annoyance. Consequently, annoyance was more affected by the direction of a heavy moving sound source than the visual information. The VR-based environment of this study turned out to be realistic in a pyschoacoustic experiment.

To select an appropriate standard floor impact source to simulate real floor impacts, objective and subjective evaluations of the floor impact sounds were conducted in a box-frame-type structure with reinforced concrete slab floors. The sounds simulated in the test were those that would result from an adult walking barefoot, children running and jumping (represented by a heavy-weight impact source, such as a bang machine or an impact ball), as well as those of a person walking in high-heels or a lightweight object being dropped (represented by a tapping machine). Similarity tests between human-made impact sounds and standard heavy-weight impact sounds were performed. Sound quality (SQ) metrics were used to predict the results of the similarity tests. These results showed that the impact sound of an impact ball is more similar to a human-made impact sound than the sound of a bang machine. A multiple regression analysis showed that loudness and roughness are significant factors describing the results of similarity judgment among SQ metrics. Much of the data from the standard impact sources, measured in reinforced concrete floors with rigid floor coverings, have been collected. An empirical relationship was established to convert the impact pressure sound level from the bang machine or tapping machine to that from the impact ball. This study indicates that the use of an impact ball is reliable for simulating human impact sounds.

Scattered sound fields in an opera house were objectively and subjectively evaluated through acoustical measurements in a 1:10 scale model and through auditory preference tests. Acoustical characteristics were measured in the stalls area with and without diffusers, both on the sidewalls close to the proscenium and in the soffit of the side balcony. Installed diffusers reduced the initial time delay gap and amplitude of the first reflected sound, and decreased sound pressure level (SPL), reverberation time (RT), and early decay time (EDT) at most seats due to the increased scattering and absorption. After diffuser installation, C(80) and 1-IACC(E3) increased at the front seats and decreased at the rear seats. Subjective evaluations showed that the preference of scattered sound fields correlates highly with loudness and reverberance. It was also found that EDT and SPL are dominant parameters describing subjective preference for scattered sounds in this experimental condition.

Opera performance conveys both visual and auditory information to an audience, and so opera theaters should be evaluated in both domains. This study investigates the effect of static visual and auditory cues on seat preference in an opera theater. Acoustical parameters were measured and visibility was analyzed for nine seats. Subjective assessments for visual-only, auditory-only, and auditory-visual preferences for these seat positions were made through paired-comparison tests. In the cases of visual-only and auditory-only subjective evaluations, preference judgment tests on a rating scale were also employed. Visual stimuli were based on still photographs, and auditory stimuli were based on binaural impulse responses convolved with a solo tenor recording. For the visual-only experiment, preference is predicted well by measurements taken related to the angle of seats from the theater midline at the center of the stage, the size of the photographed stage view, the visual obstruction, and the distance from the stage. Sound pressure level was the dominant predictor of auditory preference in the auditory-only experiment. In the cross-modal experiments, both auditory and visual preferences were shown to contribute to overall impression, but auditory cues were more influential than the static visual cues. The results show that both a positive visual-only or a positive auditory-only evaluations positively contribute to the assessments of seat quality.

Psychoacoustical and autocorrelation function (ACF) parameters were employed to describe the temporal fluctuations of refrigerator noise during starting, transition into/from the stationary phase and termination of operation. The temporal fluctuations of refrigerator noise include a click at start-up, followed by a rapid increase in volume, a change of pitch, and termination of the operation. Subjective evaluations of the noise of 24 different refrigerators were conducted in a real living environment. The relationship between objective measures and perceived noisiness was examined by multiple regression analysis. Sound quality indices were developed based on psychoacoustical and ACF parameters. The psychoacoustical parameters found to be important for evaluating noisiness in the stationary phase were loudness and roughness. The relationship between noisiness and ACF parameters shows that sound energy and its fluctuations are important for evaluating noisiness. Also, refrigerator sounds that had a fluctuation of pitch were rated as more annoying. The tolerance level for the starting phase of refrigerator noise was found to be 33 dBA, which is the level where 65% of the participants in the subjective tests were satisfied.

The effects of stage absorption on reverberation times in opera houses were investigated using computer simulations and scale model measurements. The reverberation time (RT) was measured in stalls seating with and without variable stage elements (e.g., fly curtains, side curtains, cycloramas, and stage sets). The absorption coefficients of the walls and ceiling of the stage houses were varied accordingly. It was found that variable stage elements have a significant influence on reverberation times in seating areas, particularly for a reverberant stage house, due to the low absorption of the walls and ceiling in the stage house. It was also found that the absorption coefficients of the walls and ceiling should be over 0.5 to avoid RT decreases of over 10% due to the absorption of the variable stage elements. In addition, coupled room effects were investigated both with and without variable stage elements and the results show that double slope was not found in the opera houses investigated in this study.

The effects of wall diffusing elements on sound-field diffuseness were investigated in a tenth-scale model hall and in a real recital hall. Acoustical measurements were carried out in both halls to measure the surface diffusivity of the lateral walls. In the scale model, the surfaces of the lateral walls and the soffits were covered with diffusers; in the recital hall, the front halves of both lateral walls were treated using reflective panels and absorptive materials. Objective characteristics were investigated using conventional room acoustic parameters and the number of peaks (Np) computed for the measured impulse responses, which were recorded under diffusive, reflective, and absorptive conditions. In addition, as a measure of the diffuse sound fields, the relative standard deviations (RSDs) of the acoustical parameters were investigated. The diffusive surfaces caused a decrease in the standard deviation of the early decay time and an increase in the Np at higher frequency bands. Auditory experiments using a paired comparison method revealed that the perception of subjective diffuseness could be quantified by using Np. In addition, one listener group's preference was correlated with Np and varied depending on different wall surface treatments.

Stage acoustics is an important characteristic for concert halls, both for the acoustic quality on stage and for the audience. However, relatively little research has been conducted into the question. This study was based on the investigation of an actual concert hall stage, that of the Seoul Arts Center Concert Hall in Korea. The stage acoustics was evaluated in the actual hall, and with two models: a 1:25 scale model and a computer model. The study was based on the stage support parameter ST1 proposed by Gade as a measure of support for individual performers [Acustica 65, 193-203 (1989)]. The variation of support was measured on the empty stage of the actual hall and in the two models. The effect of musicians on stage, the effect of moving the orchestra, the effect of ceiling height and of stage-wall profile were also investigated. Conclusions are drawn both relating to the Seoul Concert Hall stage and stages in general.

A framework for localization of the received source emission was implemented in enclosures based on generalized cross correlation (GCC) weighting with phase transform (PHAT) function. It was to achieve the goal of capturing meaningful sounds including speech in actual environments. The effects of room reverberation and ambient noise on the performance of the system were investigated with a linear microphone array. Experiments were performed in different environments with different RT and background noise levels. The sound sources are consisting of pink noise and speech sources were used to observe the relationship between localization accuracy and room acoustical parameters. Results for evaluation indicated that the location of the reflections was noticeable for accurately detection of the sources in reverberant and noisy environments.

The effect of diffusing elements on the variance of indoor acoustical quality is defined as “diffuseness,” and the perception of diffuse sounds is mainly affected by the absorption and diffusion coefficients of surface materials in performance spaces. To characterize sound-field diffuseness, the acoustic parameters of a room, along with impulse-based diffusivity indices are calculated from the binaural room impulse responses. Then, auditory experiments are carried out for using convolved sounds, by investigating the acoustical attributes defined for perceived diffuseness: density of reflection, smoothness of decay, smoothness of reflection, and isotropic directivity. Diffuseness normally reduces the bass ratio and increases the brilliance, thereby increasing the clarity but decreasing the sound strength. In addition, the installed diffusers objectively increase envelopment, intimacy, and diffusion perception. It is seen that the direct sound level supported by the amount of diffuse reflections are related...

A design process of diffusing surfaces has been verified by comparing with acoustic parameters in different scale models of a concert hall. A 1:50 scale model was used to determine locations of the diffusers as the main diffusing surfaces, and a 1:25 scale model was used to determine the structural height and density of the stage diffuser by examining the amount of diffusion on the stage. In addition, a 1:10 scale model was used to design the exact shapes of the diffusers by measuring the scattering and diffusion coefficients of them. The diffusers were installed on the concert hall stage and sidewalls of the auditorium; acoustic parameters, such as EDT, G, C80, and Np were measured to examine the amount of diffusion in the hall. As a result, the relative standard deviations of the parameters RT, EDT, and G decreased, whereas Np values increased. In the case of Np, the change was consistent with the variation of the diffusion amount. In conclusion, when designing a diffusing surface in a concert hall, the...

Based on 1:10 scale models and computer simulations performed in this study, the number of players in an orchestra and their sound absorption are suggested as important factors affecting the sound in the hall. For the computer simulation, scale models of players were constructed and the absorption rates were measured in the reverberation chamber. The simulation results suggest that a sound absorption rate per person is affected by the density of the occupied area of the players, and the sound absorption coefficient is determined for the space per player. When comparing two spaces of different sizes with the same number of players, the reverberation time of the auditorium is largely affected by the players when the space is larger. If more than 5% of the sound absorbing area of the hall is occupied by players, the reverberation time is remarkably reduced because of the sound absorption of the players. Therefore, the results from this study can be utilized to more accurately predict the reverberation and cl...

This study investigates the effect of temporal decay on perception of heavy-weight floor impact sounds through auditory experiments. Heavy-weight impact sounds were recorded in apartment buildings with a box-framed type reinforced concrete structure using a rubber ball. Temporal decay was quantified by using the decay rate (DR), defined as the sound pressure level (SPL) decrease per second [dB/s], and the distribution of DR for heavy-weight impact sounds was calculated. An auditory experiment was conducted in order to examine the just noticeable difference (JND) of DR, which was determined by the criteria of 75% correct answers by subjects. It was found that the JND of DR is around 11 dB/s. Based on the distribution and JND of DR, another experiment was conducted to investigate the effect of DR on annoyance perception of heavy-weight floor impact sounds in relation to the level differences. The results indicate that SPL and DR significantly influence annoyance perception; the scale value of annoyance increases with decreasing DR and increasing SPL. It was also found that the degree of satisfaction with regards to impact sounds can be improved by increasing DR, by controlling the sound field of the receiving room.

The aim of this study is to investigate the effect of audio-visual components on environmental quality to improve soundscape. Natural sounds with road traffic noise and visual components in urban streets were evaluated through laboratory experiments. Waterfall and stream water sounds, as well as bird sounds, were selected to enhance the soundscape. Sixteen photomontages of a streetscape were constructed in combination with two types of water features and three types of vegetation which were chosen as positive visual components. The experiments consisted of audio-only, visual-only, and audio-visual conditions. The preferences and environmental qualities of the stimuli were evaluated by a numerical scale and 12 pairs of adjectives, respectively. The results showed that bird sounds were the most preferred among the natural sounds, while the sound of falling water was found to degrade the soundscape quality when the road traffic noise level was high. The visual effects of vegetation on aesthetic preference were significant, but those of water features relatively small. It was revealed that the perceptual dimensions of the environment were different from the noise levels. Particularly, the acoustic comfort factor related to soundscape quality considerably influenced preference for the overall environment at a higher level of road traffic noise.

This study proposes a soundwalk procedure for evaluating urban soundscapes. Previous studies, which adopted soundwalk methodologies for investigating participants' responses to visual and acoustic environments, were analyzed considering type, evaluation position, measurement, and subjective assessment. An individual soundwalk procedure was then developed based on asking individual subjects to walk and select evaluation positions where they perceived any positive or negative characteristics of the urban soundscape. A case study was performed in urban spaces and the results were compared with those of the group soundwalk to validate the individual soundwalk procedure. Thirty subjects (15 architects and 15 acousticians) participated in the soundwalk. During the soundwalk, the subjects selected a total of 196 positions, and those were classified into 4 groups. It was found that soundscape perceptions were dominated by acoustic comfort, visual images, and openness. It was also revealed that perceived elements of the acoustic environment and visual image differed across classified soundscape groups, and there was a difference between architects and acousticians in terms of how they described their impressions of the soundscape elements. The results show that the individual soundwalk procedure has advantages for measuring diverse subjective responses and for obtaining the perceived elements of the urban soundscape.

The aim of this study is to characterize urban spaces, which combine landscape, acoustics, and lighting, and to investigate people's perceptions of urban soundscapes through quantitative and qualitative analyses. A general questionnaire survey and soundwalk were performed to investigate soundscape perception in urban spaces. Non-auditory factors (visual image, day lighting, and olfactory perceptions), as well as acoustic comfort, were selected as the main contexts that affect soundscape perception, and context preferences and overall impressions were evaluated using an 11-point numerical scale. For qualitative analysis, a semantic differential test was performed in the form of a social survey, and subjects were also asked to describe their impressions during a soundwalk. The results showed that urban soundscapes can be characterized by soundmarks, and soundscape perceptions are dominated by acoustic comfort, visual images, and day lighting, whereas reverberance in urban spaces does not yield consistent preference judgments. It is posited that the subjective evaluation of reverberance can be replaced by physical measurements. The categories extracted from the qualitative analysis revealed that spatial impressions such as openness and density emerged as some of the contexts of soundscape perception.

Several heavyweight impact sources have been used in applying standardized excitation forces to evaluate the noise generation characteristics of building floors. In this study, heavyweight sources (a bang machine and an impact ball) were filmed with a high-speed camera on the period of deformation and restitution of the impact. The generated impact force was measured, and the effects of the taken deforming shapes were investigated. Experimental modal analysis was performed to determine the natural frequencies and mode shapes of the impact sources. With respect to deforming shapes during impacts, the influence of the mode shapes was clearly demonstrated, especially for the impact ball. Using the measured modal properties, the impact force was predicted and compared to the measured excitation force. By comparing the transient variation of the excitation force and its frequency spectrum, the influence of the modal characteristics of the source on the generated impact force was investigated.

In this study, urban soundscapes containing combined noise sources were evaluated through field surveys and laboratory experiments. The effect of water sounds on masking urban noises was then examined in order to enhance the soundscape perception. Field surveys in 16 urban spaces were conducted through soundwalking to evaluate the annoyance of combined noise sources. Synthesis curves were derived for the relationships between noise levels and the percentage of highly annoyed (%HA) and the percentage of annoyed (%A) for the combined noise sources. Qualitative analysis was also made using semantic scales for evaluating the quality of the soundscape, and it was shown that the perception of acoustic comfort and loudness was strongly related to the annoyance. A laboratory auditory experiment was then conducted in order to quantify the total annoyance caused by road traffic noise and four types of construction noise. It was shown that the annoyance ratings were related to the types of construction noise in combination with road traffic noise and the level of the road traffic noise. Finally, water sounds were determined to be the best sounds to use for enhancing the urban soundscape. The level of the water sounds should be similar to or not less than 3 dB below the level of the urban noises.

This study investigated the effect of a spatial factor, the magnitude of interaural cross-correlation (IACC) function, on subjective responses to heavy-weight floor impact sounds. Heavy-weight impact sounds were generated by a heavy/soft impact source (impact ball) in real apartments, so that impact sound pressure levels (SPLs) (L(Amax)) and IACC could be analyzed. Just noticeable differences (JNDs) of impact SPL and IACC were investigated through the use of impact ball sounds. JNDs were determined by the criteria of 75% correct answers by participants, and it was found that JNDs of impact SPL and IACC were around 1.5 dB and 0.12-0.13, respectively. In addition, the annoyance caused by an impact ball was evaluated by changes in these two parameters. The results show that annoyance increased with increasing impact SPL and with decreasing IACC; the contributions of the two parameters to the scale value of annoyance were 79.3% and 20.4%, respectively. This indicates that the effects of IACC should be considered for the evaluation of annoyance, and the subjective response to impact ball sounds can be improved by controlling IACC, as well as impact SPL.

A monitoring and alarming system was designed to detect household noise occurrence in the multi-story residential buildings. This system is composed of a microphone combined with a home smart pad installed on a wall and a main server that can store data to discriminate household noise occurrence. Sound levels such as LAeq and LAmax were calculated in real time using developed digital signal processor (DSP) of the acoustical parameter analyzer in the home smart pad. A correction equation was applied based on the standard measurement method to provide accurate measurements. After measurement, the results were saved in the main server using Ethernet and inter-compared with the data of each household to discriminate the household noise occurrence. Finally, the alarm was raised depending on the decision criteria based on both the regulations of Korean government and subjective evaluation results from the previous study.

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

The modal synthesis method has been investigated to synthesize realistic virtual sounds for rigid bodies. The current methods to create realistic audio quality of sounding materials lack the ability to automatically determine material parameters. In this study, an approach is introduced to estimate material parameters that capture the inherent quality of sounding materials and extract perceptually significant features from the recorded example impulse responses. This approach is based on modal analysis using extracted material features to identify the best material parameters for linear modal synthesis (LMS). The synthesized audio produced from LMS preserves the same quality of material sound as recorded sound clips. A perceptual study was also conducted, revealing that the results of this approach are comparable with real recorded sounds in terms of perception of the materials.

The room acoustical characteristics have been investigated in temporal and spatial structures of room impulse responses (IRs) at different audience positions in real halls. The spherical microphone array of 32-channel is used for measurements process. Specular and diffusive reflections in IRs have been visualized in temporal domain with sound-field decomposition analysis. For plane wave decomposition, the spherical harmonics are used. The beamforming technique is also employed to make directional measurements and for the spatio-temporal characterization of sound field. The directional measurements by beamforming are performed for producing impulse responses for the different directions to characterize the sound. From the estimation of spatial characterization, the reflective surfaces of the hall are indicated as responsible for specular and diffusive reflections.

The microphone systems were designed to capture the real sound field for the creation of the remote virtual coexistence space: omnidirectional microphone, binaural dummy head, linear array microphones, and spherical microphone. The captured signals were applied to synthesize into the binaural signal. These binaural cues were generated using head-related transfer function (HRTF) through headphone. For the validation, the sentence recognition tests were carried out to quantify the ability of speech perception with the sentence lists for normal listeners. In addition, the readability and the naturalness were used to assess the quality of the synthesized sounds. The different noise environments were applied with different signal to noise ratio and an efficient sound capturing system was suggested by the comparing the results of the sentence recognition tests.

The number of peak (Np) in the impulse response signal (IRs) captured for the real hall have been investigated and measured by using continuous wavelet transform (CWT). Np has a relationship with perceptual diffusion as an objective characteristic that is influenced by walls scattering elements. In addition, as measuring diffuse sound fields, the CWT coefficients are used for detecting the diffusive sound. Based on the absolute coefficient values calculated from CWT analysis, a practical method of counting reflections is considered. These reflections are specified as diffusive or specular base on their similarity with the mother wavelet. Temporal and spatial representation of absolute values of CWT is presented. Auditory experiments using a paired comparison method were conducted to gauge the relationship between the Np and perceptual sound field diffusion. It is revealed that a dominant factor influencing the subjective preference in the hall was the Np that varied with different wall surface treatments.

In this study, a 1:10 scale model was used to evaluate the acoustical parameters and speech transmission indices in high-speed train cabins when the interior design factors are changed to improve speech privacy. The 1:10 scale model materials were selected by considering real measured target factors, such as reverberation time (RT) and speech level (Lp,A,s). The characteristics of the background noise in a high-speed train depend on the train’s speed; therefore, recordings of the background noise (LAeq) inside a train were considered in three situations: a stopped train, a train traveling at 100 km/h, and a train traveling at 300 km/h. The values of the STI were reproduced with the background noise levels at each speed using external array speakers with an equalizing filter in the scale model. The shapes and absorptions of chairs and interior surfaces were evaluated using scale modeling.

ISO 3382-1 describes instructions for conducting acoustical measurements in auditoria. This standard defines how to measure and derive general properties of the acoustic conditions. By applying the general instructions in ISO, a modified Np was investigated by counting the number of peaks from room impulse responses in an auditorium to characterize the sound field diffuseness. The accuracy of the parametric value in a space depends on the uncertainties involved in all stages of the measurements and analyzing processes. Uncertainties related to source/receiver characteristics, directional aspects, and computational techniques are considered in computing the modified Np. Therefore, we discuss the extent to which we are uncertain about the modified Np and the factors affecting its accuracy in all processes involved in measurements and computations.

This study explores the speech privacy criteria in passenger cars of high-speed trains. In-situ measurements were performed in running trains to analyze the acoustical characteristics of interior noises in train cabins, and laboratory experiments were conducted to determine the most appropriate single-number quantity for the assessment of speech privacy. In the listening tests, the participants were asked to rate (1) speech intelligibility, (2) speech privacy, and (3) annoyance with varying background noises and signal to noise ratio (SNR). From the results of the listening tests, the effects of background noise levels and SNR on the speech privacy and annoyance were examined and the optimum STI and background noise levels in the passenger car concerning both speech privacy and annoyance were derived.

The aim of this study is to explore influential factors on urban soundscape perception. Objective and subjective assessments of the soundscapes in various urban spaces were conducted to characterize soundscape contexts using soundwalks. Evaluations were conducted at 21 locations, including residential, office, park, and commercial spaces in Seoul: the participants assessed their perceptions of both sound and landscape environments. In addition, laboratory experiments using audio-visual stimuli were carried out to validate the dominant soundscape factors derived from the soundwalks. From the results, a perception model of urban soundscapes consisting of physical and subjective indicators was suggested using structural equation modeling.

Specular and diffuse reflections have been detected in fine spatio-temporal structures of room impulse responses (IRs) at different positions in a 1:10 scale model hall. Continuous wavelet transformation (CWT) coefficients were calculated using mother wavelet functions of the Daubechies wavelet families and specular reflections along with their degrees of diffuseness were investigated from the IRs. In CWT analysis, the early specular reflections were detected by fining their similarities with mother wavelet at different scales. While these reflections were treated as “defects” or “singularities” that embedded in the Schroeder decay curve. In addition, the time difference of arrival (TDOA) was applied to localize the reflections using a cross correlation function for time delay estimation and direction finding of binaural room IRs. The spectral characteristics in terms of delay time were calculated by auto-correlation and interaural cross-correlation functions (ACF/IACF).

The acoustical properties of a multipurpose hall (opera mode) were measured in a 1:10 scale model to investigate the effect of diffuse reflections. Measurements were made in stall areas with and without diffusers on the walls adjacent to the pit and on the side walls. The diffusers consisted of 15‐ to 25‐cm‐high hemispheres and 25‐cm high polygons. A mix of these diffusers was used to cover about 40% of the area of the side walls. It was found that 1‐IACCE3 increased at positions close to the walls adjacent to the pit and the first reflection with maximum amplitude increased in some seats. The possibility of diffuse reflections either hitting the proscenium wall or soffit close to the side wall first, as well as reflections coming from both sides of the hall explains the reason for the bunch of early reflections in the impulse responses. The effect of diffusers at each receiver position was investigated via subjective evaluation. The results from the subjective evaluation indicated that diffuse reflections were preferred to specular reflections.