scholarly journals Influence estimation of the inclination angle of the top of the noise protection barrier on its efficiency

2021 ◽  
Vol 1 (1(57)) ◽  
pp. 12-16
Author(s):  
Vitaly Zaets
Keyword(s):  
Inclination Angle ◽  
Sound Source ◽  
Sound Field ◽  
Wide Frequency Range ◽  
Sound Insulation ◽  
Frequency Range ◽  
Noise Barriers ◽  
Sound Sources ◽  
Sound Levels ◽  
Number Of Publications

The object of research is the sound field from linear sound sources around a rounded noise barrier of the same height and different angles of inclination of the top part of the barrier. It is known that the effectiveness of noise protection barriers depends primarily on the geometric dimensions of the barrier and the relative position of the sound source, barrier and area of noise protection. A large number of publications have been devoted to the study of the influence of these factors and some others, such as the influence of the earth's surface, sound absorption, sound insulation of the barrier. However, these works did not study the effect of the angle of the top part of the barrier on the change in the barrier efficiency. In this paper, the reduction of sound levels from linear sound sources around noise barriers with different inclination angle of the top part of the barrier is investigated. Rounded barriers of the same height with different radii are considered, which made it possible to simulate barriers in which the top part of the barrier has a different inclination angle. An effectiveness of such barriers for various locations of the sound source, which could also affect the establishment of a pattern of changes in the effectiveness of barriers, is also considered. In addition, the results were analyzed over a wide frequency range. The calculation of the field around such a barrier was carried out using computer simulation using the finite element method. This method allows to easily change the geometric parameters of the barrier and the position of the sound source. The barriers were considered acoustically hard. Thus, an influence of the inclination angle of the top part of the barrier on the sound field around the barrier from various locations of sound sources in a wide frequency range is analysed. The results must be taken into account when designing noise barriers to reduce noise levels from traffic flows

scholarly journals THE PECULIARITIES OF THE SOUND FIELD ENERGY DECAY IN A ROOM WITH THE USE OF DIFFERENT PULSED SOUND SOURCES/GARSO LAUKO ENERGIJOS SLOPIMO PATALPOJE YPATUMAI, NAUDOJANT SKIRTINGUS IMPULSINIUS GARSO ŠALTINIUS

1999 ◽  
Vol 5 (2) ◽  
pp. 135-140
Author(s):  
Vytautas Stauskis
Keyword(s):  
Noise Level ◽  
Sound Field ◽  
Maximum Energy ◽  
Reverberation Time ◽  
Frequency Range ◽  
Sound Sources ◽  
Low Frequencies ◽  
High Frequencies ◽  
The Difference ◽  
Field Decay

The paper deals with the differences between the energy created by four different pulsed sound sources, ie a sound gun, a start gun, a toy gun, and a hunting gun. A knowledge of the differences between the maximum energy and the minimum energy, or the signal-noise ratio, is necessary to correctly calculate the frequency dependence of reverberation time. It has been established by investigations that the maximum energy excited by the sound gun is within the frequency range of 250 to 2000 Hz. It decreases by about 28 dB at the low frequencies. The character of change in the energy created by the hunting gun differs from that of the sound gun. There is no change in the maximum energy within the frequency range of 63–100 Hz, whereas afterwards it increases with the increase in frequency but only to the limit of 2000 Hz. In the frequency range of 63–500 Hz, the energy excited by the hunting gun is lower by 15–30 dB than that of the sound gun. As frequency increases the difference is reduced and amounts to 5–10 dB. The maximum energy of the start gun is lower by 4–5 dB than that of the hunting gun in the frequency range of up to 1000 Hz, while afterwards the difference is insignificant. In the frequency range of 125–250 Hz, the maximum energy generated by the sound gun exceeds that generated by the hunting gun by 20 dB, that by the start gun by 25 dB, and that by the toy gun—by as much as 35 dB. The maximum energy emitted by it occupies a wide frequency range of 250 to 2000 Hz. Thus, the sound gun has an advantage over the other three sound sources from the point of view of maximum energy. Up until 500 Hz the character of change in the direct sound energy is similar for all types of sources. The maximum energy of direct sound is also created by the sound gun and it increases along with frequency, the maximum values being reached at 500 Hz and 1000 Hz. The maximum energy of the hunting gun in the frequency range of 125—500 Hz is lower by about 20 dB than that of the sound gun, while the maximum energy of the toy gun is lower by about 25 dB. The maximum of the direct sound energy generated by the hunting gun, the start gun and the toy gun is found at high frequencies, ie at 1000 Hz and 2000 Hz, while the sound gun generates the maximum energy at 500 Hz and 1000 Hz. Thus, the best results are obtained when the energy is emitted by the sound gun. When the sound field is generated by the sound gun, the difference between the maximum energy and the noise level is about 35 dB at 63 Hz, while the use of the hunting gun reduces the difference to about 20–22 dB. The start gun emits only small quantities of low frequencies and is not suitable for room's acoustical analysis at 63 Hz. At the frequency of 80 Hz, the difference between the maximum energy and the noise level makes up about 50 dB, when the sound field is generated by the sound gun, and about 27 dB, when it is generated by the hunting gun. When the start gun is used, the difference between the maximum signal and the noise level is as small as 20 dB, which is not sufficient to make a reverberation time analysis correctly. At the frequency of 100 Hz, the difference of about 55 dB between the maximum energy and the noise level is only achieved by the sound gun. The hunting gun, the start gun and the toy gun create the decrease of about 25 dB, which is not sufficient for the calculation of the reverberation time. At the frequency of 125 Hz, a sufficiently large difference in the sound field decay amounting to about 40 dB is created by the sound gun, the hunting gun and the start gun, though the character of the sound field curve decay of the latter is different from the former two. At 250 Hz, the sound gun produces a field decay difference of almost 60 dB, the hunting gun almost 50 dB, the start gun almost 40 dB, and the toy gun about 45 dB. At 500 Hz, the sound field decay is sufficient when any of the four sound sources is used. The energy difference created by the sound gun is as large as 70 dB, by the hunting gun 50 dB, by the start gun 52 dB, and by the toy gun 48 dB. Such energy differences are sufficient for the analysis of acoustic indicators. At the high frequencies of 1000 to 4000 Hz, all the four sound sources used, even the toy gun, produce a good difference of the sound field decay and in all cases it is possible to analyse the reverberation process at varied intervals of the sound level decay.

Empirical study on the correlation between measurement methods under diffuse and direct sound field conditions for determining sound absorption and airborne sound insulation properties of noise barriers

2021 ◽  
Vol 263 (3) ◽  
pp. 3350-3361
Author(s):  
Andreas Fuchs ◽  
Reinhard Wehr ◽  
Marco Conter
Keyword(s):  
Empirical Study ◽  
Sound Absorption ◽  
Sound Field ◽  
Research Programme ◽  
Measurement Methods ◽  
Field Conditions ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Noise Barriers ◽  
Airborne Sound

In the frame of the SOPRANOISE project (funded by CEDR in the Transnational Road Research Programme 2018) the database of the European noise barrier market developed during the QUIESST project was updated with newly acquired data. This database gives the opportunity for an empirical study on the correlation between the different measurement methods for the acoustic properties of noise barriers (according to the EN 1793 series) to further investigate the interrelationships between these methods by using single-number ratings and third-octave band data. First a correlation of the measurement methods for sound absorption under diffuse field conditions (EN 1793-1) and sound reflection under direct sound field conditions (EN 1793-5) is presented. Secondly, a correlation of the measurement methods for airborne sound insulation under diffuse field conditions (EN 1793-2) and airborne sound insulation under direct sound field conditions (EN 1793-6) is shown. While for airborne sound insulation a distinct correlation is found due to the wide data range, for sound absorption no robust correlation can be found.

Optimization of the Sound Source Position for Shaping Acoustically-Structurally Coupled Cavities

2001 ◽  
Author(s):  
Arzu Gonenc Sorguc ◽  
Ichiro Hagiwara ◽  
Qinzhong Shi ◽  
Haldun Akagunduz
Keyword(s):  
Sound Source ◽  
Sequential Quadratic Programming ◽  
Normal Modes ◽  
Sound Field ◽  
Source Strength ◽  
Source Position ◽  
Sound Sources ◽  
Coupled Cavities ◽  
Structural Loading ◽  
Initial Starting

Abstract In this study, sound field inside acoustically-structurally coupled rectangular cavity excited by structural loading and sound sources is shaped by optimizing the position of the sound source. In the optimization, Most Probable Optimal Design (MPOD) based on Holographic Neural Network is employed and the results are compared with Sequential Quadratic Programming (SQP). It is shown that source position, rather than source strength, is more effective in acoustically controlled modes. The nodal positions for in-vacuo acoustical normal modes are good candidates for initial starting points.

Active Control of Low-Frequency Sound Radiation From Vibrating Panel Using Planar Sound Sources

2001 ◽  
Vol 124 (1) ◽  
pp. 2-9 ◽  
Author(s):  
Kean Chen ◽  
Gary H. Koopmann
Keyword(s):  
Active Control ◽  
Near Field ◽  
Low Frequency ◽  
Sound Radiation ◽  
Sound Field ◽  
Sound Power ◽  
Frequency Range ◽  
Sound Sources ◽  
Frequency Sound ◽  
Secondary Sources

Active control of low frequency sound radiation using planar secondary sources is theoretically investigated in this paper. The primary sound field originates from a vibrating panel and the planar sources are modeled as simply supported rectangular panels in an infinite baffle. The sound power of the primary and secondary panels are calculated using a near field approach, and then a series of formulas are derived to obtain the optimum reduction in sound power based on minimization of the total radiate sound power. Finally, active reduction for a number of secondary panel arrangements is examined and it is concluded that when the modal distribution of the secondary panel does not coincide with that of the primary panel, one secondary panel is sufficient. Otherwise four secondary panels can guarantee considerable reduction in sound power over entire frequency range of interest.

An Introduction to Virtual Phased Arrays for Beamforming Applications

2015 ◽  
Vol 39 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Daniel Fernández Comesana ◽  
Keith R. Holland ◽  
Dolores García Escribano ◽  
Hans-Elias de Bree
Keyword(s):  
Sound Localization ◽  
Relative Phase ◽  
Phased Arrays ◽  
Sound Field ◽  
Microphone Arrays ◽  
Acoustic Sensor ◽  
Frequency Range ◽  
Acoustic Holography ◽  
Sound Sources ◽  
Single Sensor

Abstract Sound localization problems are usually tackled by the acquisition of data from phased microphone arrays and the application of acoustic holography or beamforming algorithms. However, the number of sensors required to achieve reliable results is often prohibitive, particularly if the frequency range of interest is wide. It is shown that the number of sensors required can be reduced dramatically providing the sound field is time stationary. The use of scanning techniques such as “Scan & Paint” allows for the gathering of data across a sound field in a fast and efficient way, using a single sensor and webcam only. It is also possible to characterize the relative phase field by including an additional static microphone during the acquisition process. This paper presents the theoretical and experimental basis of the proposed method to localise sound sources using only one fixed microphone and one moving acoustic sensor. The accuracy and resolution of the method have been proven to be comparable to large microphone arrays, thus constituting the so called “virtual phased arrays”.

scholarly journals SIMILARITY BETWEEN ACOUSTIC INDICATORS OF AN REAL HALL AND ITS MODEL/REALIOS SALĖS IR JOS MODELIO AKUSTINIŲ RODIKLIŲ PANAŠUMAS

1999 ◽  
Vol 5 (1) ◽  
pp. 68-73
Author(s):  
Vytautas Stauskis
Keyword(s):  
Sound Source ◽  
Sound Absorption ◽  
Sound Field ◽  
Computer Memory ◽  
Digital Converter ◽  
Reverberation Time ◽  
Frequency Range ◽  
Analog To Digital ◽  
The Real ◽  
The Difference

The similarity between acoustic indicators of an real hall and its model has been examined. A rectangular hall is 13.6 m long, 10.7 m wide and 7.0 m high. Its floor and ceiling are horizontal. The hall has plastered walls, parquet floor, and reinforced-concrete-slab ceiling. Thus, all surfaces of the hall are made of materials that reflect sound well. A hall model scaled 1:25 was made. The floor and ceiling of the model were made of fabric-based laminate and the walls were made of veneer 8 mm thick, lacquered three times. Therefore, the materials used to produce the model are similar to those of the real hall by their sound absorption properties. A 9 calibre sound pistol was used as a sound source for the investigations in the real hall. The sound signal was stored in the computer memory via a ½′ microphone, an amplifier and an analog-to-digital converter, then analysed by means of a acoustical signal analysis program developed by us. The signal was analysed within the frequency range of 50—5000 Hz. The main objective and subjective acoustical indicators of the hall were calculated using this program. A spark sound source was used for the experiments with the hall model. It was thrust through a hole in the floor in order to improve the radiation directivity diagram. The position of the sound source and a ¼′ microphone was the same in the real hall and its model. The signal was fed from the microphone to the amplifier, then to the analog-to-digital converter and recorded in the computer memory. The signal may be recorded via several different buffers allowing to record signals of varied length. The range of the frequencies investigated was from 1250 to 50000 Hz, the model scale being 1:25. The signal digitization frequency was 166.6 kHz and the digitization time was 6 mks. The decrease of the sound field of a non-filtered signal is of a similar nature during the first and the last 400 ms, i e during the early and the late periods of decrease. In the intermediate period, approximately from 500 to 3000 ms, the sound field decrease in the model exceeds the one in the real hall by only 1–3 dB. In the real hall, the sound field decrease is close to the straight line up to 2500 ms, while in the model—up to 1000 ms only, and the decrease is faster than in actual practice. The further field decrease has the character of a curve and the diffusive properties of the field are impaired. These results show that the sound field decrease in the real hall and in the model is quite similar. Investigations show that the sound field decrease in the real hall and in the model is almost analogous when the decrease is approximated every 10 dB from 0 to—30 dB. The reverberation time difference is 0.16–0.5 s and is lower than 10%. As the field decrease is approximated from − 5 to −35 dB, the reverberation time of the model exceeds that of the real hall by about 1 s, which makes up about 15%. The difference between the early reverberation time of the real hall and its model is only − 0.2 − 0.8 s even up to 500 Hz. This is mainly determined by the air sound absorption in the model at the ultrasound frequencies. As the sound field decrease is approximated from 0 to − 30 dB and from −5 to −35 dB, the difference between the reverberation time of the hall and its model in the frequency range up to 500 Hz is slight, only 0.2–0.9 s, which is less than 15%. The character of change in the sound absorption is analogous to that of the sound absorption coefficients. In the range up to 500 Hz, the sound absorption of the real hall and its model differs by 1–2 m2 only. As frequency increase, the difference reaches − 20 m2. For a non-filtered signal, the music sound clarity index C 80 is 5.6 dB for the real hall and 4.9 dB for the model.

Study of Spherical Near-Field Acoustic Holography with Rigid Spherical Microphone Array

2013 ◽  
Vol 546 ◽  
pp. 156-163
Author(s):  
Xin Guo Qiu ◽  
Ming Zong Li ◽  
Huan Cai Lu ◽  
Wei Jiang
Keyword(s):  
Sound Source ◽  
Microphone Array ◽  
Near Field ◽  
Sound Field ◽  
Acoustic Holography ◽  
Real Situation ◽  
Helmholtz Equations ◽  
Sound Sources ◽  
Array Configuration ◽  
Sphere Radius

The aim of this paper is to investigate the impacts of various parameters of rigid spherical microphone array in detecting and locating interior sound source. Helmholtz Equations are adopted to express the sound field produced by the incident field and scattered field. The gradient of the pressure is zero at the surface for the sphere is rigid. Both the incident and scattered coefficient could be obtained by solving the Helmholtz Equation using the boundary condition. Then the interior sound field could be detected and located on with the methodology of spherical near-field acoustic holography (SNAH). This study is developed in two aspects，one is configuring the microphone in various distribution in the same sphere radius, and the other one is changing the radius of sphere array. Numerical simulations are carried out to determine the optimum microphone array configuration and structure parameters. One, two, and three sound sources are arranged respectively in different displacement to the sphere center and in different angle direction to simulate the real situation. During the experiments, Omni-directional speakers and beeps are adopted as sound sources. The result shows that the method to detect and locate sound source in interior sound field is valid.

Reproduction of Phantom Sources Improves with Separation of Direct and Reflected Sounds

2015 ◽  
Vol 40 (4) ◽  
pp. 575-584
Author(s):  
Piotr Kleczkowski ◽  
Aleksandra Król ◽  
Paweł Małecki
Keyword(s):  
Sound Source ◽  
Sound Field ◽  
Angular Separation ◽  
Impulse Responses ◽  
Sound Sources ◽  
Perceptual Effect ◽  
Multichannel Systems ◽  
Virtual Acoustics

AbstractIn virtual acoustics or artificial reverberation, impulse responses can be split so that direct and reflected components of the sound field are reproduced via separate loudspeakers. The authors had investigated the perceptual effect of angular separation of those components in commonly used 5.0 and 7.0 multichannel systems, with one and three sound sources respectively (Kleczkowski et al., 2015, J. Audio Eng. Soc. 63, 428-443). In that work, each of the front channels of the 7.0 system was fed with only one sound source. In this work a similar experiment is reported, but with phantom sound sources between the front loud- speakers. The perceptual advantage of separation was found to be more consistent than in the condition of discrete sound sources. The results were analysed both for pooled listeners and in three groups, according to experience. The advantage of separation was the highest in the group of experienced listeners.

Application Analysis of Small Sound Barrier on Soundproof Windows under Line and Point Sound Sources

2013 ◽  
Vol 291-294 ◽  
pp. 1107-1112
Author(s):  
Yi Bin Lei ◽  
Mei Jun Jin
Keyword(s):  
Sound Source ◽  
Traffic Noise ◽  
Sound Insulation ◽  
Traffic Flows ◽  
Residential Areas ◽  
Sound Sources ◽  
Sound Barrier ◽  
Application Analysis ◽  
Sound Barriers ◽  
Sound Environment

Traffic noise can be classified as point and line sources according to different traffic flows. Intakes on bay windows and small sound barriers are always used to reduce the influences of traffic noise on high buildings along streets and improve sound environment in these residential areas. Through the studies of the diffraction sound attenuation difference curves of small barriers in point and line sound source conditions, this article aims at providing with not only feasible soundproof solutions and theoretical directions for the choice of sound insulation products, but also with theoretical bases for the research and exploration of acoustic proof windows. His template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

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