Sound Simulation Research Articles

Collisions in double string plucked instruments: Physical modelling and sound synthesis of the viola caipira

The viola caipira is a folk guitar widely used in traditional and modern Brazilian music. It consists, in general, of 10 metallic strings arranged in five pairs, tuned in unison or octave, with the thinnest string located in the middle. An experimental study of the viola caipira pluck by means of a high speed camera reveals some specificities of the instrument. It is found that the instrument is characterized by a double pluck excitation since the two strings of a given pair are plucked successively and rapidly. Collisions between strings arranged in the same pair are identified. A hybrid model, based on a modal approach, is carried out for sound synthesis purposes. It includes 10 strings with non-planar motions coupled with the body and collisions between strings. A finite difference scheme is used to compute the coupling forces at each time-step, which permits a set of sound simulations. The effects of string/string collisions on the viola caipira sounds are identified and discussed. It is found that the model reproduces the main vibroacoustic features of the viola caipira, among which the sympathetic string resonances and the string/string collisions observed in the video analysis.

Field Experiment of a Sonic Crystal Window

In the present study, white, pink, construction and environmental noises were evaluated in a student hostel at National University of Singapore (NUS) with a newly designed sonic crystal (SC) window using sound quality head and torso simulator. The sound head was placed at the bed and the chair in the student hostel. All recorded data were analyzed into full (100–7000[Formula: see text]Hz) and narrow (700–1400[Formula: see text]Hz) frequency ranges. For lying position and for white noise, the SC window was able to attenuate extra 6.7 and 9.5[Formula: see text]dBA of noise compared to the existing glass louver window for full and narrow frequency ranges, respectively. For full frequency range, the overall amounts of pink, construction and environmental noises attenuated by the SC window were about 4.8, 5.0 and 3.4[Formula: see text]dBA, respectively. For narrow frequency range, the overall amounts of these three type of noises attenuated by the SC window were about 2–3.9[Formula: see text]dBA higher than that of full frequency range. The overall amounts of attenuated white noise at sitting position were about 2.6 and 6.1[Formula: see text]dBA, respectively, for full and narrow frequency ranges. For full frequency range, the attenuated pink and construction noises at sitting position were about 3.8 and 4.8[Formula: see text]dBA, respectively, which were slightly lower than that at lying position. However, for narrow frequency range, the attenuated noises obtained at lying position were 2.7 and 2.5[Formula: see text]dBA higher than that at sitting position for pink and construction noises, respectively.

Effect of immersive visual stimuli on the subjective evaluation of the loudness and annoyance of sound environments in urban cities

The subjective evaluation of the sound environment of urban areas has been widely investigated in laboratories using various acoustic simulation methods. However, visual stimuli, such as videos of the original measurement environment, can also be considered to influence the sound evaluation. This paper proposes a system for the simulation of the target audiovisual environment using headphones and a head-mounted display. The inclusion of the head-mounted display provides insight into the influence of the provision of a realistic panoramic video of the target visual environment on the subjective evaluation. To provide realistic sound environments, variation in the direction of incidence of the sound caused by the rotation of the subject’s head is taken into consideration in the proposed system by dynamically updating the simulated direction of incidence using sound data recorded with a six-channel directional microphone, head-related transfer functions, and the angular data of the orientation of the head obtained by a gyro sensor installed in the head-mounted display. To validate the basic performance of the proposed sound simulation system, a subjective sound localization test was performed, and it was confirmed that appropriate sound localization performance can be achieved with the system when the subjects can freely rotate their heads. With the proposed system, a subjective evaluation experiment targeting urban sound environments was performed, and the effect of the visual stimulus on the evaluated loudness and annoyance of the sound was assessed. The evaluation scores of the loudness and annoyance of the sounds were significantly lower when panoramic videos of the original measurement locations were presented to the subjects than when videos of an anechoic chamber were presented. This suggests that the subjective evaluation of the environmental sounds without any visual information concerning the environments give a bias to the evaluated results.

When Listening Is Better Than Reading: Performance Gains on Cardiac Auscultation Test Questions.

In 2007, the United States Medical Licensing Examination embedded multimedia simulations of heart sounds into multiple-choice questions. This study investigated changes in item difficulty as determined by examinee performance over time. The data reflect outcomes obtained following initial use of multimedia items from 2007 through 2012, after which an interface change occurred. A total of 233,157 examinees responded to 1,306 cardiology test items over the six-year period; 138 items included multimedia simulations of heart sounds, while 1,168 text-based items without multimedia served as controls. The authors compared changes in difficulty of multimedia items over time with changes in difficulty of text-based cardiology items over time. Further, they compared changes in item difficulty for both groups of items between graduates of Liaison Committee on Medical Education (LCME)-accredited and non-LCME-accredited (i.e., international) medical schools. Examinee performance on cardiology test items with multimedia heart sounds improved by 12.4% over the six-year period, while performance on text-based cardiology items improved by approximately 1.4%. These results were similar for graduates of LCME-accredited and non-LCME-accredited medical schools. Examinees' ability to interpret auscultation findings in test items that include multimedia presentations increased from 2007 to 2012.

Protective earphones and human hearing system response to the received sound frequency signals

Sound is one of the most important problems in industrial environments, and it causes hearing loss at different frequencies in the workforce. Incorrect fitting of hearing protector has a negative effect on noise reduction. The present study was conducted with the aim of determination of the effective frequencies on hearing loss and variations of the sound level in different frequencies after placing the earplug. A model of ear canal with different materials was simulated. Sound pressure sensors and earplugs were placed in both sides of the ear canal. The rates of sound reduction in octave frequency signals were calculated for the simulated canal of different materials, in different distances between the microphone and the earplug with Labview software. The results of sound simulation in octave frequency signals showed that by increasing the frequency, the rates of sound reduction in different conditions also had an increasing trend. The obtained peak rates for all the situations coincided with each other at fixed frequencies. In most cases, a noise reduction in the frequency of 4000 Hz showed a high number. The maximum sound reduction was observed at 25.5 mm at frequencies below 250 Hz, which was similar to the average of human ear canal length; so the simulated model can be used to determine the performance of the protective earphones and test them at different frequencies and sound pressure levels.

Sonic Interactions in Virtual Reality: State of the Art, Current Challenges, and Future Directions

A high-fidelity but efficient sound simulation is an essential element of any VR experience. Many of the techniques used in virtual acoustics are graphical rendering techniques suitably modified to account for sound generation and propagation. In recent years, several advances in hardware and software technologies have been facilitating the development of immersive interactive sound-rendering experiences. In this article, we present a review of the state of the art of such simulations, with a focus on the different elements that, combined, provide a complete interactive sonic experience. This includes physics-based simulation of sound effects and their propagation in space together with binaural rendering to simulate the position of sound sources. We present how these different elements of the sound design pipeline have been addressed in the literature, trying to find the trade-off between accuracy and plausibility. Recent applications and current challenges are also presented.

An Exception to Mental Simulation: No Evidence for Embodied Odor Language.

Do we mentally simulate olfactory information? We investigated mental simulation of odors and sounds in two experiments. Participants retained a word while they smelled an odor or heard a sound, then rated odor/sound intensity and recalled the word. Later odor/sound recognition was also tested, and pleasantness and familiarity judgments were collected. Word recall was slower when the sound and sound‐word mismatched (e.g., bee sound with the word typhoon). Sound recognition was higher when sounds were paired with a match or near‐match word (e.g., bee sound with bee or buzzer). This indicates sound‐words are mentally simulated. However, using the same paradigm no memory effects were observed for odor. Instead it appears odor‐words only affect lexical‐semantic representations, demonstrated by higher ratings of odor intensity and pleasantness when an odor was paired with a match or near‐match word (e.g., peach odor with peach or mango). These results suggest fundamental differences in how odor and sound‐words are represented.

Numerical Simulation of High Level Sound Generated in Boiler tube Bank Duct

Numerical Simulation of High Level Sound Generated in Boiler tube Bank Duct

Geometric-integration tools for the simulation of musical sounds

During the last decade, much attention has been given to sound rendering and the simulation of acoustic phenomena by solving appropriate models described by Hamiltonian partial differential equations. In this contribution, we introduce a procedure to develop appropriate tools inspired from geometric integration in order to simulate musical sounds. Geometric integrators are numerical integrators of excellent quality that are designed exclusively for Hamiltonian ordinary differential equations. The introduced procedure is a combination of two techniques in geometric integration: the semi-discretization method by Celledoni et al. (J Comput Phys 231:6770–6789, 2012) and symplectic partitioned Runge–Kutta methods. This combination turns out to be a right procedure that derives numerical schemes that are effective and suitable for computation of musical sounds. By using this procedure we derive a series of explicit integration algorithms for a simple model describing piano sounds as a representative example for virtual instruments. We demonstrate the advantage of the numerical methods by evaluating a variety of numerical test cases.

Трехмерное моделирование и инверсия данных комплекса методов электрокаротажа в моделях сред с наклоном главных осей тензора электрической анизотропии

Трехмерное моделирование и инверсия данных комплекса методов электрокаротажа в моделях сред с наклоном главных осей тензора электрической анизотропии

Aeroacoustic computation of fluid-structure interaction problems with low Mach numbers

This contribution deals with the acoustic simulation of aerodynamical noise generated by a flow over an airfoil or by flow in a flexible channel. Since the considered flow has low Mach number the hybrid approach of acoustic analogies can be applied here with benefits. The fluid-structure-acoustic interaction problem is generally described as a quite complicated problem comprising of three different physical fields - the vibration of the elastic body, the unsteady fluid flow and the acoustics together with mutual couplings. The fluid flow in time dependent domain is governed by the incompressible Navier-Stokes equations in arbitrary Langrangian-Eulerian formulation and the elastic structure is modelled by the means of linear elasticity theory. The Lighthill analogy and acoustic perturbation equation (APE) is considered to describe the sound propagation. The simulation of fluid-structure (FSI) interaction and acoustic field is implemented using the FEM in an in-house solver. The sound sources computed from FSI results are analyzed and within sound propagation simulation the perfectly matched layer technique is used. In the end the results of Lighthill and APE analogy are compared.

Elastic behavior of glass-rubber mixed particles system

The mixture of scrap rubber particles and sands has been extensively used as geotechnical engineering recycled materials due to its environmental protection performance, light quality and excellent energy dissipation capability. The mechanical properties of the system can be modulated by the mixing ratio between soft and hard components. But the reasons for such a change on a particle scale are not yet clear. In this paper the elastic behaviors of glass-rubber mixed particles are studied by the sound velocity measurement and discrete element simulation. The velocity of compressional wave and the dynamic effective elastic modulus of mixed sample under hydrostatic stress are measured by time-of-flight method. It is found that the wave velocity is almost constant and the modulus decreases slightly with the proportion of rubber particles increasing to 20%. After that the wave velocity and modulus decrease rapidly and the system transforms from rigid-like behavior to soft-like behavior until the proportion of rubber particles reaches to 80%. When the proportion of rubber particles are more than 80%, the compressional wave velocity and the dynamic effective elastic modulus remain stable again. Such experimental results are consistent with discrete element method analyses which provide more in-depth insights into the micromechanics of the mixture. The simulation reveals that at low rubber fraction the main force chain structure is basically composed of glass particles without rubber particles, which accounts for the phenomenon that the velocity of the compressional wave is basically constant. When the glass particles and rubber particles co-construct the main force chain structure, the distribution of the normal contact force is relatively uniform at high rubber fraction. This can be regarded as the glass particles suspending in the rubber particles. An improved effective medium theory is proposed to describe the elastic behavior of the mixed particles system. It is considered that the deformation of the internal particles is relatively uniform for glass dominated mixture which satisfies the isostress hypothesis. A parallel spring model can be used to describe the nonlinear contact model of particles in such materials. On the other hand, rubber dominated mixture approximately satisfies the isostrain hypothesis, which can be described by a series spring model. The outcomes of such models are in agreement with the simulation results for rigid glass dominated mixture and soft rubber dominated mixture. This study is helpful in exploring the mechanisms that are responsible for the macroscale elastic behavior of mixed granular material from the microscopic point of view.

An automated non-destructive testing system for seam bondings in automotive serial production

The joining process of seam bond is used in automobile construction because of the non-visible joints on mounted parts such as doors, hoods or luggage compartment doors. With these components, a structure-providing inner panel is joined with the outer panel, which is visible to the customer. Besides providing stability, particularly in the event of a crash, the joining level is also filled with adhesive to increase the stability and to prevent the ingress of moisture that causes corrosion. These mechanical connections must be tested to ensure that the requirements for proper bonding have been met. As the destructive test used today requires metallographic laboratory with special trained personnel, significant scrap cost and a time consuming process control loop, considerable efforts are being made to develop a capable non-destructive and as far as possible in-line test method. State of the art non-destructive inspection systems for seam bonds are insufficient regarding full part accessibility and reliability in terms of detectability and validation. This paper is focussed on new developed free configurable three-transducer ultrasonic phased array technology including algorithms for data validation and evaluation for an automated process control loop in the automotive car body shop. The paper end with an statistical classification based on an 5-month measurement campaign under industrial in-line conditions. In a first step, a list of possible defects was collected and the detectability in different seam areas was calculated by sound field simulation of the amplitude signals. Second, based on the results from simulation, a measurement setup as excitation sequence was defined. Based on the theoretical findings a inspection system was designed and realized. Within a measurement campaign the inspection system was evaluated in terms of detectability of minimal defect size under non-laboratory conditions. This includes a permanent proof of coupling conditions, monitoring of misalignments, e.g. tilting and surface defects of the car body. In the last step, the testing system is build up and tested within the assembly line. These measurement results show that the identification of common process defects is possible.

Sound Quality Experiments in a Student Hostel with Newly Designed Sonic Crystal Window

A new design of sonic crystal window was designed to replace the existing glass louver window in a student hostel in NUS in order to achieve good balancing of natural ventilation, daylighting and noise mitigation. Numerical studies were performed on the SC window to confirm the window design. The noise level inside the room was measured using sound quality head and torso simulator for simulated white noise, pink noise and construction noise on the ground floor as well as the actual environmental noise. Ten human subjects were asked to evaluate the construction noise and environmental noise inside the room. Psychoacoustics analyses were also performed on these two types of noises. The SC window was designed such that it can attenuate the noise at frequency range of traffic noise. The SC window was able to attenuate extra 4.59 and 9.40 dBA of white noise at full frequency range and frequencies ranging from 700 to 1400 Hz, respectively. The overall amount of pink noise attenuated by the SC window was similar to that of white noise. It can be concluded that gender affected the human subjective perception toward construction noise. All human subjects felt that the degree of annoyance for environmental noise passing through the glass louver window was higher than the SC window. The SC window would successfully reduce the loudness of the construction and environmental noises compared to the glass louver window.

Interactive footsteps sounds modulate the sense of effort without affecting the kinematics and metabolic parameters during treadmill-walking

Previous research has shown that walkers provided with interactive simulations of footstep sounds on a surface material different from the one they are walking upon, experience pseudo-haptic illusions and adjust their walking kinematic according to the perceived surfaces’ compliance. Since walking on real grounds with different degrees of compliance leads to different metabolic costs, an open question is whether pseudo-haptic illusions created by interactive footstep sounds are able to affect the metabolic parameters.This study investigated whether metabolic cost and movement’s kinematics are affected by such interactive auditory feedback in a constrained condition as walking on a treadmill. Participants were walking on a treadmill under three listening conditions: actual footsteps sounds, interactive simulations of footstep sounds on gravel and snow. The metabolic and kinematic data, as well as the perceived exertion, sense of effort, easiness, and feeling of sinking were recorded.Results showed that interactive footstep sounds provided during treadmill walking did not affect kinematic and metabolic parameters of walking, while they were effective in modulating participants’ perception.These results suggest that in a constrained and non self-selected pattern of locomotion the sound of action, even though correctly perceived, is not strong enough to induce a change in the metabolic and kinematics of the locomotion.

Imaging of heart acoustic based on the sub-space methods using a microphone array

Background and objectivesHeart disease is one of the leading causes of death around the world. Phonocardiogram (PCG) is an important bio-signal which represents the acoustic activity of heart, typically without any spatiotemporal information of the involved acoustic sources. The aim of this study is to analyze the PCG by employing a microphone array by which the heart internal sound sources could be localized, too. MethodIn this paper, it is intended to propose a modality by which the locations of the active sources in the heart could also be investigated, during a cardiac cycle. In this way, a microphone array with six microphones is employed as the recording set up to be put on the human chest. In the following, the Group Delay MUSIC algorithm which is a sub-space based localization method is used to estimate the location of the heart sources in different phases of the PCG. ResultsWe achieved to 0.14cm mean error for the sources of first heart sound (S1) simulator and 0.21cm mean error for the sources of second heart sound (S2) simulator with Group Delay MUSIC algorithm. The acoustical diagrams created for human subjects show distinct patterns in various phases of the cardiac cycles such as the first and second heart sounds. Moreover, the evaluated source locations for the heart valves are matched with the ones that are obtained via the 4-dimensional (4D) echocardiography applied, to a real human case. ConclusionsImaging of heart acoustic map presents a new outlook to indicate the acoustic properties of cardiovascular system and disorders of valves and thereby, in the future, could be used as a new diagnostic tool.

Brass Instruments Design Using Physics-Based Sound Simulation Models and Surrogate-Assisted Derivative-Free Optimization

This paper presents a method for design optimization of brass wind instruments. The shape of a trumpet's bore is optimized to improve intonation using a physics-based sound simulation model. This physics-based model consists of an acoustic model of the resonator, a mechanical model of the excitator, and a model of the coupling between the excitator and the resonator. The harmonic balance technique allows the computation of sounds in a permanent regime, representative of the shape of the resonator according to control parameters of the virtual musician. An optimization problem is formulated in which the objective function to be minimized is the overall quality of the intonation of the different notes played by the instrument. The design variables are the physical dimensions of the resonator. Given the computationally expensive function evaluation and the unavailability of gradients, a surrogate-assisted optimization framework is implemented using the mesh adaptive direct search algorithm (MADS). Surrogate models are used both to obtain promising candidates in the search step of MADS and to rank-order additional candidates generated by the poll step of MADS. The physics-based model is then used to determine the next design iterate. Two examples (with two and five design optimization variables) demonstrate the approach. Results show that significant improvement of intonation can be achieved at reasonable computational cost. Finally, the perspectives of this approach for computer-aided instrument design are evoked, considering optimization algorithm improvements and problem formulation modifications using for instance different design variables, multiple objectives and constraints or objective functions based on the instrument's timbre.

音場シミュレーションと音空間レンダリング

計算機環境の発達やFDTD (Finite Difference Time Domain) 法などの簡便なアルゴリズムの普及により，音場シミュレーションが身近になってきた．本稿では，FDTD法により音場を解析するときの理論を解説し，GPU (Graphics Processing Unit) などの高速並列演算デバイスへの実装法についても簡単に触れる．また，音場シミュレーションの可聴化への応用として，波動性を考慮した3次元音場計算により聴取位置での音圧波形を数値的に計算した上で，立体音響技術などで3次元的に可聴化する音空間レンダリングについても解説する．更に，近年高性能化が著しいHMD (Head Mounted Display) による3D CG映像との連携によるインタラクティブなレンダリングについても述べる．

Meta-Analysis, Systematic, and Integrative Reviews: An Overview

Over the past 10 years there has been an increasing interest is evidence based simulation practice. At the same time multiple reviews of simulation have been published that provide data on the science of simulation. Nurse educators utilizing simulation understand it takes less time to read a methodologically sound simulation review than it does to read multiple research studies or the many articles included in an integrative or review of simulate literature. Understanding the processes used for different kinds of reviews can bring clarity to the quality and usefulness of a review. This short communication is an effort to provide information on thedefinition of a meta-analysis, systematic, and integrative review. To support reading or conducting a review several resources that can support the process are offered.

Printone

This paper presents an interactive design interface for three-dimensional free-form musical wind instruments. The sound of a wind instrument is governed by the acoustic resonance as a result of complicated interactions of sound waves and internal geometries of the instrument. Thus, creating an original free-form wind instrument by manual methods is a challenging problem. Our interface provides interactive sound simulation feedback as the user edits, allowing exploration of original wind instrument designs. Sound simulation of a 3D wind musical instrument is known to be computationally expensive. To overcome this problem, we first model the wind instruments as a passive resonator, where we ignore coupled oscillation excitation from the mouthpiece. Then we present a novel efficient method to estimate the resonance frequency based on the boundary element method by formulating the resonance problem as a minimum eigenvalue problem. Furthermore, we can efficiently compute an approximate resonance frequency using a new technique based on a generalized eigenvalue problem. The designs can be fabricated using a 3D printer, thus we call the results "print-wind instruments" in association with woodwind instruments. We demonstrate our approach with examples of unconventional shapes performing familiar songs.