Spatial Distribution Prediction of Steady-State Sound Field With the Ray-Tracing Method

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Zhong-Jin Jiang ◽  
Tie-Jun Cui
Keyword(s):  
Spatial Distribution ◽  
Steady State ◽  
Ray Tracing ◽  
Three Dimensional ◽  
Sound Field ◽  
Energy Matrix ◽  
Sound Energy ◽  
Sound Fields ◽  
Level Ii ◽  
Level I

A novel two-level space volume partition (SVP) algorithm based on the ray-tracing technique is proposed to predict the spatial distribution of the steady-state sound field. The sound space is subdivided into voxels in two levels. The voxels of the level-I are of greater size and comparable to the space walls, and the ray-wall intersection points are calculated based on this level of voxels. Then each level-I voxel is hierarchically subdivided into small voxels of level-II, the size of which is determined according to the needed solution in the sound field description. The sound field spatial distribution is predicted based on this level of voxels. A three-dimensional energy matrix is set up to memorize the spatial distribution of sound energy. The numbers of the row, column, and layer of the energy matrix are equal to those of the level-II voxels, namely, each element in the energy matrix corresponds to a level-II voxel. When a sound ray enters a voxel, its sound energy is calculated and recorded in the corresponding element of the energy matrix. When all the sound rays have been traced over, the sound energy spatial distribution in the sound space has been established in the energy matrix. The sound pressure level (SPL) in a certain plane or along a certain line can be calculated and imaged directly from the energy matrix. The novel two-level SVP algorithm can finish the simulation more efficiently than the traditional SVP algorithm. Experiments were performed to measure the SPL in steady-state sound fields, and the results were consistent with the predicted results.

Acoustical Design Study on Application of Absorption Materials

2014 ◽  
Vol 711 ◽  
pp. 546-549
Author(s):  
Wei Lin ◽  
Wei Hwa Chiang
Keyword(s):  
Computer Simulation ◽  
Energy Distribution ◽  
Ray Tracing ◽  
Impulse Response ◽  
Background Noise ◽  
Three Dimensional ◽  
Design Phase ◽  
Design Study ◽  
Sound Energy ◽  
Reinforcement System

Taipei Top Church Auditorium is a hall primarily intended for praise and worship. A three dimensional ray tracing computer simulation was used to provide sound energy distribution on the audience area of the hall, realistic design have been performed. The volume of the hall is 24600m3, which is occupied for 2200 people and equipped the hall with acoustical curtains by modifying its acoustical characteristics. Objective measurements of impulse response are reported, and background noise control and noise isolation are also be considered in the design phase. Reinforcement system is conducted to meet all the activity for the acoustical environments.

scholarly journals A Revised Sound Energy Theory Based on a New Formula for the Reverberation Radius in Rooms with Non-Diffuse Sound Field

2015 ◽  
Vol 40 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Higini Arau-Puchades ◽  
Umberto Berardi
Keyword(s):  
Sound Absorption ◽  
Sound Field ◽  
Critical Distance ◽  
Sound Level ◽  
Reverberation Time ◽  
Sound Energy ◽  
Sound Fields ◽  
Energy Theory ◽  
New Interpretation ◽  
New Formula

Abstract This paper discusses the concept of the reverberation radius, also known as critical distance, in rooms with non-uniformly distributed sound absorption. The reverberation radius is the distance from a sound source at which the direct sound level equals the reflected sound level. The currently used formulas to calculate the reverberation radius have been derived by the classic theories of Sabine or Eyring. However, these theories are only valid in perfectly diffused sound fields; thus, only when the energy density is constant throughout a room. Nevertheless, the generally used formulas for the reverberation radius have been used in any circumstance. Starting from theories for determining the reverberation time in non- diffuse sound fields, this paper firstly proposes a new formula to calculate the reverberation radius in rooms with non-uniformly distributed sound absorption. Then, a comparison between the classic formulas and the new one is performed in some rectangular rooms with non-uniformly distributed sound absorption. Finally, this paper introduces a new interpretation of the reverberation radius in non-diffuse sound fields. According to this interpretation, the time corresponding to the sound to travel a reverberation radius should be assumed as the lower limit of integration of the diffuse sound energy

Diffusion Equation-Based Finite Element Modeling of a Monumental Worship Space

2017 ◽  
Vol 25 (04) ◽  
pp. 1750029 ◽  
Author(s):  
Zühre Sü Gül ◽  
Ning Xiang ◽  
Mehmet Çalışkan
Keyword(s):  
Finite Element ◽  
Diffusion Equation ◽  
Geometric Model ◽  
Three Dimensional ◽  
Sound Field ◽  
Equation Model ◽  
Field Analysis ◽  
Room Acoustics ◽  
Sound Energy ◽  
Worship Space

In this work, a diffusion equation model (DEM) is applied to a room acoustics case for in-depth sound field analysis. Background of the theory, the governing and boundary equations specifically applicable to this study are presented. A three-dimensional geometric model of a monumental worship space is composed. The DEM is solved over this model in a finite element framework to obtain sound energy densities. The sound field within the monument is numerically assessed; spatial sound energy distributions and flow vector analysis are conducted through the time-dependent DEM solutions.

scholarly journals Validation and application of three-dimensional auralisation during concert hall renovation

2020 ◽  
Vol 27 (4) ◽  
pp. 311-331
Author(s):  
Lamberto Tronchin ◽  
Francesca Merli ◽  
Massimiliano Manfren ◽  
Benedetto Nastasi
Keyword(s):  
Cross Correlation ◽  
Three Dimensional ◽  
Sound Field ◽  
Musical Instrument ◽  
Impulse Responses ◽  
Acoustic Parameters ◽  
Field Representation ◽  
Sound Fields ◽  
Acoustic Quality ◽  
Fifth Order

During the renovation of auditoria and concert halls, the acoustic quality is normally evaluated from measurements of impulse responses. One possibility for evaluating the acoustic quality from the measurements (the simulations) consists of convolving anechoic music with the measured (or simulated) impulse responses. In this way, a psycho-acoustic test is achieved using a virtual sound field representation. The listening room ‘Arlecchino’ at the University of Bologna includes ambisonics (up to fifth order) and stereo-dipole playback for virtual reproduction of sound in rooms. In this article, the effectiveness of the listening room ‘Arlecchino’ is first analysed, comparing acoustic parameters obtained from binaural impulse responses measured in some opera houses (in Italy) and auditorium (in Japan) with those virtually measured after the virtual reconstruction obtained in the listening rooms. The similarity between real and virtual sound fields, has been evaluated by comparing different acoustic parameters calculated by real and virtual sound fields, in four halls in different configurations, by means of the stereo-dipole method. In the second part of the article, the listening room was used to analyse the variation in interaural cross-correlation measurements in rooms obtained considering different anechoic sound signals convolved with the binaural impulse responses, to quantify the variation of the interaural cross correlation with different motifs. For this purpose, two different musical instrument digital interface musical motifs, very different from each other for their music characteristics, have been considered. Moreover, for each musical motif, different sound characteristics (i.e. different musical instruments) were considered, to consider both the rhythmic and timbre aspect.

scholarly journals Identifying Three-Dimensional Facial Fluctuating Asymmetry in Normal Pediatric Individuals: A Panel Assessment Outcome Study of Clinicians and Observers

2019 ◽  
Vol 8 (5) ◽  
pp. 648 ◽  
Author(s):  
Pang-Yun Chou ◽  
Rafael Denadai ◽  
Shih-Heng Chen ◽  
Hsiao-Jung Tseng ◽  
Chih-Kai Hsu ◽  
...  
Keyword(s):  
Fluctuating Asymmetry ◽  
Three Dimensional ◽  
Facial Asymmetry ◽  
Outcome Study ◽  
Higher Symmetry ◽  
Level Ii ◽  
Level I

This study measured three-dimensional facial fluctuating asymmetry in 600 normal and healthy Taiwanese individuals (6 to 12 years old) and assessed the perceptions of increasing levels of facial fluctuating asymmetric severity by using a panel composed of 20 clinicians (surgical professionals), as well as 20 adult and 40 pre-adolescent observers. On average, this normal cohort presented a facial fluctuating asymmetry of 0.96 ± 0.52 mm, with 0.52 ± 0.05, 0.67 ± 0.09, 1.01 ± 0.10, and 1.71 ± 0.36 mm for levels I, II, III, and IV of severity, respectively. For all categories of raters, significant differences in the average symmetry–asymmetry scale values were observed, with level I < level II < level III = level IV (all p < 0.01, except for level III vs. IV comparisons with p > 0.05). For level I, pre-adolescent observers presented a significantly (p < 0.05) higher symmetry–asymmetry scale value than adult observers, with no significant (all p > 0.05) differences for other comparisons. For overall facial asymmetry and levels II, III, and IV, no significant (all p > 0.05) differences were observed. This study reveals that the normal pediatric face is asymmetric and the panel assessment of facial fluctuating asymmetry was influenced by the level of severity and the category of raters and contributes to the literature by revealing that pre-adolescent raters present a similar or higher perception of facial asymmetry than adult raters.

CLINICAL FEATURES, INDICATIONS AND RESULT OF TRACHEOTOMY

2017 ◽  
pp. 50-55
Author(s):  
Duc Luu Ngo ◽  
Tu The Nguyen ◽  
Manh Hung Ho ◽  
Thanh Thai Le
Keyword(s):  
Clinical Features ◽  
University Hospital ◽  
Female Ratio ◽  
Tube Obstruction ◽  
Level Ii ◽  
Study Results ◽  
Male Female Ratio ◽  
Hospital Patients ◽  
Level I

Background: This study aims to survey some clinical features, indications and results of tracheotomy at Hue Central Hospital and Hue University Hospital. Patients and method: Studying on 77 patients who underwent tracheotomy at all of departments and designed as an prospective, descriptive and interventional study. Results: Male-female ratio was 4/1. Mean age was 49 years. Career: farmer 44.2%, worker 27.2%, officials 14.3%, student 7.8%, other jobs 6.5%. Respiratory condition before tracheotomy: underwent intubation 62.3%, didn’t undergo intubation 37.7%. Period of stay of endotracheal tube: 1-5 days 29.2%, 6-14 days 52.1%, >14 days 18.7%. Levels of dyspnea before tracheotomy: level I 41.4%, level II 48.3%, level III 0%, 10.3% of cases didn’t have dyspnea. Twenty cases (26%) were performed as an emergency while fifty seven (74%) as elective produces. Classic indications (37.7%) and modern indications (62.3%). On the bases of the site, we divided tracheostomy into three groups: high (0%), mid (25.3%) and low (74.7%). During follow-up, 44 complications occurred in 29 patients (37.7%). Tracheobronchitis 14.3%, tube obstruction 13%, subcutaneous empysema 10.4%, hemorrhage 5%, diffcult decannulation 5.2%, tube displacement 3.9%, canule watery past 2.6%, wound infection 1.3%. The final result after tracheotomy 3 months: there are 33 patients (42.9%) were successfully decannulated. In the 33 patients who were successfully decannulated: the duration of tracheotomy ranged from 1 day to 90 days, beautiful scar (51.5%), medium scar (36.4%), bad scar (12.1%). Conclusions: In tracheotomy male were more than female, adult were more than children. The main indication was morden indication. Tracheobronchitis and tube obstruction were more common than other complications. Key words: Tracheotomy

Sign in / Sign up

Export Citation Format

Share Document