Kinds Of Sound Sources Research Articles

Noise within hospital wards: a survey method

Noise pollution is one of the most disturbing environmental factors. It directly affects people's lives, especially vulnerable people such as children, old-age, and hospital patients. Hospitals are complex buildings with manifold spaces and facilities where different users live with different sensitivity to noise. Several studies highlight the discomfort that patients, staff, and visitors experience in hospitals due to inadequate noise levels. All this leads to stress, sleep disorders, interference in communication, aggression, and annoyance. Noise exposure in hospitals is due to several sound sources. Each varies throughout the day, and their detection could be challenging. The present study proposes a clustering technique to analyze long-term sound level meter monitoring in an Italian hospital (Pisa, Tuscany). Equivalent short-term levels obtained with an interval time of 0.1 s are used as the database to exploit the occurrences curves of different chunks of the monitoring. Then, through a validated method, the spectra of different kinds of sound sources are reconstructed via the Gaussian Mixture Model. Results are compared with near-field measurements of single sources.

Temporal and Spatial Characteristics of Soundscape Ecology in Urban Forest Areas and Its Landscape Spatial Influencing Factors

We explored the spatial and temporal characteristics of the urban forest area soundscape by setting up monitoring points (70 × 70 m grid) covering the study area, recorded a total of 52 sound sources, and the results showed that: (1) The soundscape composition of the park is dominated by natural sounds and recreational sounds. (2) The diurnal variation of sound sources is opposite to that of temperature, 6:00–9:00 is the best time for the public to perceive birdsong, and after 18:00, the park is dominated by insect chirps. (3) The PSD (power spectral density) and the SDI (soundscape diversity index) of the park are greatly affected by public recreation behaviors, and some recreation behaviors may affect the vocal behavior of organisms such as birds. (4) Spaces with high canopy density can attract more birdsong and recreational sounds in summer, and the combination of “tree + lake” can attract more birdsong. Vegetation has a significant dampening effect on traffic sound. (5) Landscape spatial elements, such as the proportion of hard ground, sky, trees, and shrubs, have a significant impact on changes in the PSD, the SDI and different kinds of sound sources. The research results provide effective data support for improving the soundscape of urban forests.

Visualization of a chorus structure in multiple frog species by a sound discrimination device.

We developed a sound discrimination device to identify and localize the species of nocturnal animals in their natural habitat. The sound discrimination device is equipped with a microphone, a light-emitting diode, and a band-pass filter. By tuning the center frequency of the filter to include a dominant frequency of the calls of a focal species, we enable the device to be illuminated only when detecting the calls of the focal species. In experiments in a laboratory room, we tuned the sound discrimination devices to detect the calls of Hyla japonica or Rhacophorus schlegelii and broadcast the frog calls from loudspeakers. By analyzing the illumination pattern of the devices, we successfully identified and localized the two kinds of sound sources. Next, we placed the sound discrimination devices in a field site where actual male frogs (H. japonica and R. schlegelii) produced sounds. The analysis of the illumination pattern demonstrates the efficacy of the developed devices in a natural environment and also enables us to extract pairs of male frogs that significantly overlapped or alternated their calls.

냉장고 정상상태 소음의 음질 인덱스 개발을 위한 심리음향학적 연구

Household refrigerator radiates noise of which the pattern is dependent on the operating condition of its parts, such as compressor, flow fans, etc. Thus the refrigerator noise has a variety of frequency characteristics. Therefore, it is required to consider the noise characteristics for evaluating the noise quality and eventually developing the sound quality index of the refrigerator noise. In this study, five units of household refrigerator were selected to measure their noises that were used to generate sound sources for jury test of the study. The measured noises of five refrigerators were divided into ten kinds of sound source by considering operating condition and frequency characteristics. Additionally, the ten sources were each edited to have the same SPL of 30 ㏈A. Totally twenty kinds of sound sources (10-original SPL, 10-edited SPL 30 ㏈A) were evaluated by twenty-two subjects, and compared with their sound quality metrics. It was found that only the loudness of the metrics was meaningfully correlated with the subjective evaluation. The rests, sharpness, roughness and fluctuation strength, were not related. The conclusion of this study is that a new sophisticated index is necessary to be developed to qualitatively evaluate the household refrigerator noise.

Narrowcasting and Multipresence for Music Auditioning and Conferencing in Social Cyberworlds

We describe a musical cyberworld, Folkways in Wonderland, in which avatarrepresented users can find and listen to selections from the Smithsonian Folkways world music collection. When audition is disturbed by cacophony of nearby tracks or avatar conversations, one’s soundscape can be refined since the system supports narrowcasting, a technique which allows information streams to be filtered. Our system supports two different kinds of sound sources: musical selections and avatar conversation (voice-chat). Narrowcasting for music enables aesthetic focus; narrowcasting for talk enables cognitive focus. The former is required for dense presentation of musical sound, the latter for virtual worlds in which many avatars are expected to be able to interact. An active listener can fork self-identified avatars using a novel multipresence technique, locating representatives at locations of interest, each clone capturing respective soundscapes, controlled using narrowcasting functions {self, non-self} × {select (solo), mute, deafen, attend}. Likewise one can participate in a conference and at the same time join a global tour of music. Our music browser is architected to use MX: IEEE 1599, a comprehensive, multilayered, music description standard. Using our cyberworld as a virtual laboratory, we evaluated the effectiveness of narrowcasting when auditioning music and conferencing. Experimental results suggest that narrowcasting and multipresence techniques are useful for collaborative music exploration and improve user experience. We also got positive feedback from the participants regarding narrowcasting representations, variously based on colors, symbols, and icons.

Sound generation assignment device, music sound generator and sound generation assignment process program

A CPU sets an application of music sound generation to each of plural ports, and a priority to the set application, and further sets the maximum number of channels that assign an arbitrary sound source to each port from plural kinds of sound sources and produce sounds. When a new sound generation request is supplied to a certain port in which all sound generation channels of the port are currently generating sounds, and when the sound generation channels to be used for the sound generation are in short, the CPU supplies the sound generation request to a channel not producing a sound currently in other port to which the application of the same priority is set.

무향실에 있어서의 음압레벨과 거리정위와의 관계

According to a lot of investigations, distance perception is influenced by many important cues such as sound pressure level, reflections from the room surface, binaural difference (ITD and ILD), a kind of sound source, and head related transfer functions (HRTF). Two psychoacoustical experiments on auditory distance perception were conducted to examine the effectiveness of the sound pressure level loudness as one of the physical cues in the auditory distance perception under a constant loudspeaker`s output level and a constant sound level at the subject`s position in the absence of reflections in an anechoic room. Our experimental results showed that the perceived distance of sound image is closer than actual sound source distance with the constant loudspeaker`s output level and the constant sound level. Futhermore, the perceived distance of a sound image with constant sound level increased when the actual distance increases up to approximately 2 m while the perceived distance saturated when the sound source distance exceed 2 m. On the other hand, when the condition of loudspeaker`s output level was kept constantly, the perceived distance of sound image increased up to around 3m, longer than the conditions of constant sound level at the subject`s position. We found that the change in the loudness as a function of distance plays an important role in the auditory distance perception in the absence of reflections..

A pair of spectral notches which plays a role as a spectral cue in the vertical localization, and it's application to estimation of sound source elevation from binaural signals

The author [Applied Acoustics, 68, 835‐850 (2007)] proposed a parametric HRTF model for vertical sound localization. The parametric HRTF is recomposed only of the spectral peaks and notches extracted from the measured HRTF. The results of the median plane localization tests, which were carried out using the parametric HRTFs with various combinations of spectral peaks and notches, show that the pair of first and second notches (N1 and N2) above 5 kHz can be regarded as spectral cues. In this research, estimation of the elevation of sound source in the upper median plane by extracting N1 and N2 frequencies from binaural input signal was carried out. The kinds of sound sources were female voice, male voice, music, white noise, and pink noise. The results show that the estimation is accurate for almost of all the elevation and of all the kind of sound sources.

Sound source identification for precision information equipment having many kinds of sound sources

These days, precision information equipment having multifunction with high qualities in an office environment is demanded. Sound quality in this equipment has become a very important factor in addition to reduction of the sound-pressure level. MFP (multifunction peripheral) has many functional parts and operational modes, so it makes uncomfortable transient sounds in one cycle. The primary sound section to decide the sound quality of the MFP was estimated by sound quality evaluation as in previous research. Main uncomfortable sounds could be confirmed at the steady-state sound section as the single copy mode and at the particular transient sound section in one cycle as the ten-times continuous copies mode. So, it is necessary to identify the position of uncomfortable sound sources at each mode for comfortable sound design. Principal component analysis (PCA) using acceleration measured by accelerometers and sound pressure measured by microphones is applied to identify the number of sound sources. Sound-pressure distribution in one cycle from the MFP having many kinds of sound sources can be measured by microphone array at each moment. As a result, the sound source position can be identified by using PCA and sound-pressure distribution.

Study of preferred reverberation time dependent upon the kinds of sound sources

Study of preferred reverberation time dependent upon the kinds of sound sources