Distribution Of Sound Energy Research Articles

A Prediction Method for Acoustic Intensity Vector Field of Elastic Structure in Shallow Water Waveguide

Compared with scalar sound field, vector sound field explained the spatial structure of sound field better since it not only presents the sound energy distribution but also describes the sound energy flow characteristics. Particularly, with more complicated interaction among different wavefronts, the vector sound field characteristics of an elastic structure in a shallow water waveguide are worthy of studying. However, there is no reliable prediction method for the vector sound field of an elastic structure with a high efficiency in a shallow water waveguide. To solve the problem, transfer functions in the waveguide have been modified with some approximations to apply for the vector sound field prediction of elastic structures in shallow water waveguides. The method is based on the combined wave superposition method (CWSM), which has been proved to be efficient for predicting scalar sound field. The rationality of the approximations is validated with simulations. Characteristics of the complex acoustic intensity, especially the vertical components are observed. The results show that, with constructive and destructive interferences in the depth direction, there could be quantities of crests and vortices in the spatial structure of time-dependent complex intensity, which manifest a unique dynamic characteristic of sound energy. With more complicated interactions among the wavefronts, a structure source could not be equivalent to a point source in most instances. The vector sound field characteristics of the two sources could be entirely different, even though the scalar sound field characteristics are similar. Meanwhile, source types, source parameters, ocean environment parameters, and geo parameters may have influence on the vector sound field characteristics, which could be explained with the normal mode theory.

Analysis of the Relationship Between form and Qi in Architectural Space

This paper discusses the concept and essence of "Qi" in Chinese traditional culture. It is considered that "Qi" is the source of all things, and "Qi" in architectural space is the unity of material, energy and information flow flowing and changing in architectural space. It is the basic condition and operation mechanism of life activities and events. Three main aspects of the influence of "form" on "Qi" of architectural space are put forward: air flow, sound field, sunlight and other radiation. This paper analyzes on the relationship between "Qi" and "form" in architectural space, and expounds the influence mechanism of space form on "Qi". The "forms" of space should be conducive to the harmony of Yin Qi and Yang Qi. Different "form" have different effects on the distribution of sound field energy and information in the space, and this difference can have a direct and significant impact on the user's personal feelings, that is, different "shapes" form different "Qi", so as to have a significant impact on the actual effect of the building space. The appropriate "forms" of the building can obtain the right amount of sunlight (visible light, infrared, ultraviolet), shield harmful rays and other high-speed flying objects. The space form follows the principle of "lucky Qi goes curve", which can play the role of shielding through layers of barriers. The architectural space full of "Qi" is the ideal living environment we pursue. The "forms" of architectural space can have an important influence on the generation of "Qi". Only when the building adopts the appropriate "forms", can it get the space that is really suitable for users, and form "Qi" in the space, so as to facilitate the harmonious coexistence of people and environment. The ultimate goal of architectural design and construction practice is to find and build places that can produce "Qi".

Overhead stage canopies in a coupled volume theatre: Effects on the sound energy distribution and on the secondary reverberation

Nowadays, opera houses are often used for symphonic music, even though the intrinsic characteristics of these theatres are not suited for this purpose, due to their coupled volumes and high absorption of the fly tower. When symphonic music is performed in these halls an overhead stage canopy is often used to enhance the orchestral performance. In the present work, the effects of a canopy array in a coupled volume theatre were studied. The array canopy was designed and installed based on Geometric Acoustic (GA) simulations calibrated with in-situ measurements. Results showed peculiar effects on the sound energy distribution through space: the sound strength values depends on the “effective” volume of the theatre, varying with the sound source position. Moreover, when the stage is covered by the canopy array, the sound strength depends on the distance from the aperture instead of the distance from the sound source position. In other words, the decay curve is “tilt” by “effective volume” and “shifted” by the canopy array. Furthermore, the changes in sound behaviour due to the canopy array may be considered as a switch-off of the secondary reverberation effect.Nowadays, opera houses are often used for symphonic music, even though the intrinsic characteristics of these theatres are not suited for this purpose, due to their coupled volumes and high absorption of the fly tower. When symphonic music is performed in these halls an overhead stage canopy is often used to enhance the orchestral performance. In the present work, the effects of a canopy array in a coupled volume theatre were studied. The array canopy was designed and installed based on Geometric Acoustic (GA) simulations calibrated with in-situ measurements. Results showed peculiar effects on the sound energy distribution through space: the sound strength values depends on the “effective” volume of the theatre, varying with the sound source position. Moreover, when the stage is covered by the canopy array, the sound strength depends on the distance from the aperture instead of the distance from the sound source position. In other words, the decay curve is “tilt” by “effective volume” and “shifted” by the...

The release call of Rhaebo guttatus (Anura: Bufonidae)

ABSTRACTThe bufonid genus Rhaebo contains 13 species, Rhaebo guttatus being one of the two species that occur in Brazil. Here we describe for the first time the release call of R. guttatus from the Brazilian Amazonia. Release calls are highly variable both in the temporal and in the frequency domains. The advertisement and release calls of Rhaebo guttatus are distinguished from each other by their temporal envelope, distribution of sound energy, and calling emission patterns. The acoustic characterization of release calls in Rhaebo could be potentially informative in the taxonomy of this genus, as previously reported for members of the bufonid genus Rhinella.

Parameter study of sound energy distribution in cuboid extra-large spaces

The aim of this paper is to explore the sound energy distribution in cuboid extra-large spaces. The surface absorption and height are studied as the parameters using the image method. Air absorption is also discussed in this paper. The results show that the difficulty of reducing the noise increases with the increasing volume in extra-large spaces. Even if the ratio between the equivalent absorption area and the total surface is kept constant, the efficiency of noise reduction decreases by approximately 21% in this study. The absorption areas on the floor and the walls have a better performance on noise reduction than that on the ceiling. When the initial height of an extra-large space with general ratio of three dimensions is continuously halved, the variation in the noise level is close to a fixed value, and when the initial height continuously doubled, the noise level decreased approximately exponentially. The predicted difference between with and without consideration of air absorption increases linearly with the source-receiver distance.

Acoustic comfort in a worship space made of cross-laminated timber

The construction of a new worship space in cross-laminated timber provides a good opportunity to include acoustic needs in the whole design development. The surface porosity and the lightweight of wooden elements may be carefully considered in order to improve the intelligibility of priests’ voice. In this work, a practical approach for obtaining a global acoustic comfort using sustainable materials is provided, using geometrical acoustic simulations. Material properties and architectural geometries were taken into account in order to evaluate subjective reverberation, speech intelligibility, and spatial perception over the whole audience. Results show how the sound energy distribution in the case study follows the sound field models proposed by scholars and how the ceiling shape—inspired by industrial sheds—contributes to the acoustic comfort of the faithfuls.

The Analysis of Acoustic Propagation Characteristic Affected by Mesoscale Cold-Core Vortex Based on the UMPE Model

The ocean mesoscale vortex can make uneven distribution of sound energy, which has a significant impact on underwater acoustic equipment, weapons and submarine warfare. Based on the observed data of 2014 West Pacific sea oceanographic survey, the influence of the properties, strength, position and depth of the mesoscale vortex on the acoustic propagation characteristics is simulated by the parabolic equation. Our observed vortex is a typical cyclone-type cold vortex in the Kuroshio extension body, and the cold water turns on intensely at the center of vortex. The effect depth of vortex is 500 m, and then, the parabolic equation of acoustic model is used to analyze and simulate the impact of mesoscale cold-core vortex on acoustic transmission loss. Results show that the horizontal perturbation of the surface velocity caused by mesoscale vortex has a great influence on the spatial distribution of water sound field. The cold vortex makes the position of the convergence zone move forward, with the width reduced, and the gain efficiency enhanced. When sound propagates outside of the cold-core vortex, compared with inside of the cold-core vortex, the assembled areas are backward, with the width increased, and gain effect weakened. The non-uniform hydrological environment caused by the ocean mesoscale vortex is a key modulating factor of the abnormal variation of acoustic energy in spatial distribution.

Discrimination of empty and filled intervals marked by auditory signals with different durations and directions of intensity change.

A time interval marked by two short sounds ("empty interval") is perceived to be longer when one or more short sounds are inserted within this time interval ("filled interval"). This illusion is known as the filled-duration illusion (FDI), which has been mainly observed above 500 ms. Previous evidence has mostly shown, however, that the FDI within 500 ms is not robust due to individual differences. FDI in this short range has been less influenced by the properties of sound markers (such as amplitude, time duration, and sound energy distribution). I questioned whether the mixed evidence in the short range could be due to the methods and time ranges adopted. Here, I asked whether and how the perceived duration of both the empty interval and the filled interval (a continuous beep) was modulated by markers with different yet short durations, and by markers with intensity changes (ascending vs. descending). The results showed that the longer markers led to more expansion of the perceived time interval than did the short markers. The empty interval (300 ms) was perceived as shorter in the rising intensity (first tone marker)-decreasing intensity (second tone marker) condition, but as longer in the decreasing-decreasing condition. However, the filled interval (300 ms) bounded in the decreasing-decreasing condition was perceived as shorter. Therefore, perception of short empty and filled intervals (enclosed by auditory marks) could be modulated by the temporal properties of the markers. Those findings could be accounted for by the Gestalt perceptual groupings between the auditory markers and the to-be-timed gap/stimulus intervals in an adaptive way.

Experimental investigations on sound energy propagation in acoustically coupled volumes using a high-spatial resolution scanning system.

The aim of this work is to study the sound field distribution in an experimental scale-model of two coupled rooms. An automatic scanning mechanism moves a microphone in small grid steps to measure room impulse responses at each grid point. The measurements cover the entire two-dimensional area of the coupled rooms. Sound energy distributions can be analyzed in the form of animated visual displays, revealing sound propagation across the coupling aperture and inside each room. This paper describes the measurement results, and the analysis method, which offer deep insights into the temporal development of a sound field in coupled spaces.

Enhancing Energy Security through Utilization of Local Resources

Remote rural villages in Indonesia do not have sufficient infrastructure to maintain an economically sound energy generation and distribution. Sparse area and low population hinder national electricity company PLN (Perusahaan Listrik Negara) to connect these remote rural villages to the national grid. Most of the villages lie in the palm oil plantation, where renewable biomass resources from the Palm Oil Mill wastes are plentiful. Untapped biomass resources could be the answer to energy security issue in the remote rural area. Berau Regency in East Kalimantan Province has many villages located in the palm oil plantation area. Nearly all of the palm oil processing plants in Berau use palm shell and fiber to power the mill. Some of them have the agreement with PLN to sell their excess power. This scheme can be applied to provide electricity to villages around the palm oil mills. However, it is unreliable since the amount of excess electricity produced keeps fluctuating. This paper explores the idea of village-owned biomass/biogas power plant that is owned and operated by the villagers themselves. That way, the village can ensure its energy security using sustainable local resources. In conclusion, the investment cost of biomass/biogas power plant cannot be provided by village annual budget. Although the villages in Berau Regency have a relatively high annual budget, wich is about Rp2 billion to Rp5 billion, the investment costs of biomass/biogas power plant is even higher. According to the economic analysis of biomass/biogas power plant development, a biomass power plant with 1,7 MW capacity can cost up to Rp46 billion. Moreover, a biogas power plant with 1 MW capacity costs around 41 billion. It is not possible for the villages to finance the power plant development by themselves. Therefore, the private sector is needed to implement biomass/biogas utilization for rural electrification from palm oil waste. With the Net Present Value (NPV) up to Rp 65.078.072.000,00 and Internal Rate of Return (IRR) of 20% for biomass power plant and Rp14.330.070.000,00 and 10% for biogas power plant, it is economically feasible and profitable for private enterprise to undertake. The challenges are for the government to encourage the private sector to invest and for PLN to sign Power Purchase Agreement with these palm oil enterprises rather than just Excess Power Agreement.
 JEL Classification: I39Keywords: Biomass, biogas, renewable energy, palm oil waste utilization

Diffusion Equation-Based Finite Element Modeling of a Monumental 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.

Effects of variable acoustic elements on the spatial sound field in multipurpose venues

The design of multipurpose venues typically includes variable acoustic elements which adjust the acoustics of the space to support the intended use. The most common approach to vary the acoustics of a venue is to use variable absorption, often in the form of heavy drapery and/or acoustic felt banners. These elements are often characterized by changes in reverberation time, but their position also impacts the spatial distribution of room energy. In order to study the effects of variable acoustic elements on the three-dimensional sound field at specific audience locations, spatial impulse response measurements were taken in a number of venues using a 32-element spherical microphone array. The venues ranged from a small recital hall of 400 seats to a typical multipurpose hall with 1300 seats to a 2500-seat concert hall with variable acoustics. Beamforming techniques were used to analyze the effects of the variable acoustic elements on the spatial and temporal distribution of sound energy at several receiver locations in each venue. The sound fields in these venues will be compared to those measured in dedicated concert halls, which have been measured for recent work on the topic of listener envelopment. [Work supported by NSF Award 1302741.]

Establishment and Analysis of False Vocal Folds Hypertrophy Model in Excised Canine Larynges

This study aimed to investigate the role of false vocal folds (FVFs) medialization in phonation and the acoustic impact of ventricular hypertrophy by establishing an FVF hypertrophy model. A prospective in vitro experiment was carried out. The study was carried out using a pseudolung platform with high-speed camera in a soundproof room. Control, degree I, and degree II FVFs hypertrophy were simulated in 10 excised larynges via fructose injection of 0.1 mL for degree I and 0.25 mL for degree II. Mean flow rate (MFR), fundamental frequencies (F0), formants, and sound pressure level were measured with a subglottal pressure of 1.5 kPa and 2.5 kPa, respectively. When the subglottal pressure was controlled at both at 1.5 kPa and at 2.5 kPa, the degree of FVF hypertrophy significantly influenced the distribution of the formants, F0, and MFR in excised canine larynges. Increasing the degree of hypertrophy was associated with a decrease in F0 and an increase in MFR. In degree II FVF hypertrophy models, the sound pressure level and the first formant were significantly higher (P < 0.05) than in normal models. Hypertrophy of the FVFs has a significant influence on the distribution of sound energy and is associated with changes in sound quality.

Développer l’ACT face à la douleur chronique. L’efficience : un nouvel argument en faveur du changement ?

The human auditory system is modeled by different auditory models representing the distribution of speech sound energy in different channels across the cochlea using filter-banks of different bandwidths. In previous algorithms of non-intrusive speech quality evaluation, auditory features are determined using these auditory models on per frame basis and then averaged over the entire speech utterance. In these approaches, the effect of impulsive noise and other non-stationary noise effects get averaged over the utterance. To include the variations in the features of speech over time in the speech utterance, a multiple time-scale features approach has been proposed as the speech features vary from frame to frame that accounts for variation of noise characteristics over the speech utterance and thus its affect on quality mapping. In this work, non-intrusive speech quality evaluation has been done as an optimal linear combination of quality mapping called objective mean opinion score (MOS), computed using multiple time-scale estimates of features. The objective MOS of each of the multiple time-scale estimates (the combination of multiple active speeches) are obtained using a probabilistic approach. The overall objective MOS of the speech utterance is computed by taking the optimal linear combination of the estimated objective MOS using multiple time-scale estimates of features, where the optimality is based on the minimum mean square error (MMSE) criterion or correlation maximization criterion. The results are given in terms of Pearson's correlation coefficient and root mean square error (RMSE) between the subjective MOS and the estimated overall objective MOS for three different standard databases. The results have been compared with a single time-scale features approach, the ITU-T Recommendation P.563 and recent algorithms.

Non-intrusive speech quality estimation as combination of estimates using multiple time-scale auditory features

The human auditory system is modeled by different auditory models representing the distribution of speech sound energy in different channels across the cochlea using filter-banks of different bandwidths. In previous algorithms of non-intrusive speech quality evaluation, auditory features are determined using these auditory models on per frame basis and then averaged over the entire speech utterance. In these approaches, the effect of impulsive noise and other non-stationary noise effects get averaged over the utterance. To include the variations in the features of speech over time in the speech utterance, a multiple time-scale features approach has been proposed as the speech features vary from frame to frame that accounts for variation of noise characteristics over the speech utterance and thus its affect on quality mapping. In this work, non-intrusive speech quality evaluation has been done as an optimal linear combination of quality mapping called objective mean opinion score (MOS), computed using multiple time-scale estimates of features. The objective MOS of each of the multiple time-scale estimates (the combination of multiple active speeches) are obtained using a probabilistic approach. The overall objective MOS of the speech utterance is computed by taking the optimal linear combination of the estimated objective MOS using multiple time-scale estimates of features, where the optimality is based on the minimum mean square error (MMSE) criterion or correlation maximization criterion. The results are given in terms of Pearson's correlation coefficient and root mean square error (RMSE) between the subjective MOS and the estimated overall objective MOS for three different standard databases. The results have been compared with a single time-scale features approach, the ITU-T Recommendation P.563 and recent algorithms.

Audio Tracking in Noisy Environments by Acoustic Map and Spectral Signature.

A novel method is proposed for generic target tracking by audio measurements from a microphone array. To cope with noisy environments characterized by persistent and high energy interfering sources, a classification map (CM) based on spectral signatures is calculated by means of a machine learning algorithm. Next, the CM is combined with the acoustic map, describing the spatial distribution of sound energy, in order to obtain a cleaned joint map in which contributions from the disturbing sources are removed. A likelihood function is derived from this map and fed to a particle filter yielding the target location estimation on the acoustic image. The method is tested on two real environments, addressing both speaker and vehicle tracking. The comparison with a couple of trackers, relying on the acoustic map only, shows a sharp improvement in performance, paving the way to the application of audio tracking in real challenging environments.

Microphone array geometry optimization for traffic noise analysis.

This paper outlines an approach for obtaining microphone array geometry for use in traffic noise analysis. The designed array has a smaller number of microphones compared to existing solutions, thereby reducing the cost of system realization. The array geometry is irregular, consists of 24 microphones, and was obtained by an optimization procedure that minimizes beampatterns sidelobes. Microphone position optimization was performed in the frequency band from 300 Hz to 2000 Hz, defined by traffic noise characteristics. The designed array is used in ongoing research dedicated to the analysis of angular distribution of incident traffic noise sound energy impeding a facade in urban environment.

Sound transmission through an acoustic porous metasurface with periodic structures

We report an analytical, numerical, and experimental study of sound transmission through a metasurface fabricated by porous materials, detailing systematically the factors that influence acoustic properties. The design of the metasurface is composed of four elements with varying properties, which are aligned in a periodic manner. The structures are carefully designed to form a uniform phase shift profile in one period. It is able to refract an incidence wave in an anomalous yet controllable way. A good agreement of refraction behavior between simulated and experimental results is achieved by the study. Furthermore, we systemically summarize the relationships between the refraction and the incidence angles for structures with various ratios of wavelengths and period lengths. Remarkably, the study proves that the propagation directions and the number of refracted waves are only affected by period lengths at a specified frequency. The phase shift profile only has an influence on energy distribution in the refraction region. The study suggests that a careful design of phase shift profile plays an important role in controlling sound energy distribution of the periodic structure, which is vital for applying this kind of porous metasurface in sound absorption and isolation in the future.

Estill Voice Training and voice quality control in contemporary commercial singing: an exploratory study

Estill Voice Training (EVT) is a widely known programme for developing vocal skills based on partitioning the process of vocal production in order to reach control of specific structures in the vocal mechanism. The present retrospective small-scale exploratory study aims at reporting preliminary data about the efficacy of EVT – in terms of voice quality control on a specific vocal exercise – in contemporary commercial singers with a Certificate of Figure Proficiency (CFP). Thirty-five contemporary commercial singers (professional or semi-professional pop and rock singers) with no vocal complaints were recruited. The experimental group was composed of twenty singers who studied EVT and had a CFP. The control group was composed of fifteen singers who studied in Italian contemporary popular music institutions but were not familiar with EVT. Voice quality control was assessed through acoustic and perceptual analysis on a specific vocal exercise requiring sound pitch, perturbation and spectral energy distribution control. The acoustic analysis showed some significant differences between the two groups of singers both in sound perturbation control and spectral energy distribution control, suggesting a higher voice quality control ability for the experimental group. The perceptual evaluation confirmed a higher ability for the experimental group to produce recognizable voice qualities in this specific task. The reported preliminary results seem to suggest EVT as an effective educational system for developing voice quality control ability in contemporary commercial singers.

Investigations on sound energy decays and flows in a monumental mosque.

This work investigates the sound energy decays and flows in the Süleymaniye Mosque in İstanbul. This is a single-space superstructure having multiple domes. The study searches for the non-exponential sound energy decay characteristics. The effect of different material surfaces and volumetric contributions are investigated using acoustic simulations and in situ acoustical measurements. Sound energy decay rates are estimated by Bayesian decay analysis. The measured data reveal double- or triple-slope energy decay profiles within the superstructure. To shed light on the mechanism of energy exchanges resulting in multi-slope decay, spatial sound energy distributions and energy flow vectors are studied by diffusion equation model (DEM) simulations. The resulting sound energy flow vector maps highlight the contribution of a sound-reflective central dome contrasted with an absorptive carpeted floor in providing delayed energy feedback. In contrast, no multi-slope energy decay pattern is observed in DEM simulations with a bare marble floor, which generates a much more diffuse sound field than in the real situation with a carpeted floor. The results demonstrate that energy fragmentation, in support of the non-exponential energy decay profile, is due to both the sound absorption characteristics of materials and to their distributions, as well as to relations between the subvolumes of the mosque's interior.