On the sampling conditions for reconstruction of an acoustic field from a finite sound source

2002 ◽  
Vol 111 (2) ◽  
pp. 940-946 ◽  
Author(s):  
Makoto Tabei ◽  
Mitsuhiro Ueda
Keyword(s):  
Acoustic Field ◽  
Sound Source ◽  
Sampling Conditions

scholarly journals Estimating the influence of double-sided rounded screens on the acoustic field around a linear sound source

2021 ◽  
Vol 3 (5 (111)) ◽  
pp. 38-46
Author(s):  
Vitalii Didkovskyi ◽  
Vitaly Zaets ◽  
Svetlana Kotenko ◽  
Volodymyr Denysenko ◽  
Yuriy Didenko
Keyword(s):  
Acoustic Field ◽  
Cross Sections ◽  
Sound Source ◽  
Finite Thickness ◽  
Sound Field ◽  
Algebraic Equations ◽  
The Road ◽  
Study Results ◽  
On The Road ◽  
The Impact

This paper reports a study into the acoustic field of transport flow around noise protection screens located on both sides of the sound source. Most research on noise protection involving noise protection screens relates to the assessment of the effectiveness of screens located on one side of the noise source. The influence of the second screen on the effectiveness of the first one has been investigated only experimentally. Therefore, it is a relevant task to assess the mutual impact of the two screens between which the linear sound source is located. A problem was stated in such a way that has made it possible to derive an analytical solution and find a sound field around a linear sound source. In this case, the sound source was limited on both sides by acoustically rigid screens with finite thickness. The screens' cross-sections were shaped as part of a ring with arbitrary angles and the same radius. The problem was solved by the method of partial domains. This method has made it possible to obtain an infinite system of algebraic equations that were solved by the method of reduction. Such an approach to solving a problem allows a given solution to be applied for different cases of the mutual location of screens, source, and territory protected from noise. The study results help estimate a field between the screens, the dependence of increasing sound pressure on the road on the geometric size of the screen and the width of the road. In addition, the solution resulted in the ability to assess the impact of one screen on the efficiency of another in the frequency range of up to 1,000 Hz. It has been shown that the mutual impact of screens could reduce the screen efficiency by 2 times. The study reported here could make it possible to more accurately calculate the levels of the sound field from traffic flows when using noise protection screens, which is often performed in practice when designing new and reconstructing existing highways.

scholarly journals THE DIRECT SOUND, THE EARLY REFLECTIONS AND THE INTERRELATION BETWEEN THEIR ENERGY AND THE NEAR AND THE REMOTE ACOUSTIC FIELDS/TIESIOGINIS GARSAS, ANKSTYVI ATSPINDŽIAI IR JŲ ENERGIJOS RYŠYS SU ARTIMU IR TOLIMU GARSO LAUKU

1996 ◽  
Vol 2 (7) ◽  
pp. 70-74
Author(s):  
V. Stauskis
Keyword(s):  
Acoustic Field ◽  
Sound Source ◽  
Time Interval ◽  
Acoustic Fields ◽  
Sound Energy ◽  
The Third ◽  
Structure Changes ◽  
Sound Reflection ◽  
The Relationship

The paper deals with the dependence of the near and remote acoustic field limits on the relationship between the direct sound and the first reflections' energy. A hall with the dimensions 13.6×10.7×7 m was chosen for the investigation. There were 120 semi-upholstered chairs in the hall, with no people. The selected investigation points were located 1 m and 11 m from the sound source. This choice was determined by the fact that in both cases the early sound reflections differ greatly in the delay time with respect to the direct sound and in their intensity. A question as to what duration of the direct sound should be taken in the measurements is of great importance. In his previous work the author has examined the relationship between the energies of the near and the remote acoustic fields as well as its dependece on the hall volume and absorption. It has been established that while seeking the ratio between the direct sound energy and the remaining energy it is better to assess the early sound reflections and not the diffusional acoustic field. In this paper, the duration of the direct sound was taken as 5 ms according to the recommendations found in the literature. It has been found experimentally that the duration of the direct sound is 1–1.7 ms and not 5 ms as recommended by the literature. There are no reflections in the time interval from 0 to 50 ms, only of the diffracted from the operator, microphone etc. The duration of the direct sound depends on the quality of the sound source itself, i.e. on the power of the shot etc. During the experiment the duration of the direct sound was established for each case separately. When the microphone is located at 1 m from the sound source, strong direct sound prevails. After 6.05 ms the first reflection from the floor reaches the listener. Its amplitude is lower by 4.2 dB than that of the direct sound. After 6.39 and 7.43 ms, two reflections arrive with amplitudes lower by 11.4 and 15.3 dB respectively than those of the direct sound. The next sound reflection from the ceiling reaches the listener as late as after 33.85 ms. In the time interval from 6.6 ms to 33.85 ms no reflections reach the listener. In this interval, the amplitude of the diffracted reflections affected by the interference is lower by as much as 20–55 dB than that of the direct sound. Such distribution of the reflection structure is only possible near the sound source. The reflection structure changes along with the increase in the distance from the source. Investigations show that in the case when the microphone is 1 m from the sound source the ratio between the direct sound energy and the first reflection energy is equal to 9.32, or 9.7 dB. The direct sound energy prevails and is bigger than the first reflection energy by a factor of 10. When the second reflection arrives after 6.39 ms, the direct sound energy is more than the sound energy of two reflections by a factor of 3.12 only, or 4.9 dB. The third reflection, which is less energetic, reduces this difference to 2.95, or to 4.7 dB. Further, to 33.85 ms there follows an area without sound reflections where only the diffracted sound is found. Due to this the energy ratio is only slightly reduced. Only after 43 ms the energy of the direct sound and the reflections of various intensity that have arrived earlier is equal to the direct sound energy. In this case the energies come to equilibrium in the performers' area after 45–50 ms. These results show that direct sound only prevails in the performers' zone in the course of the first 45–50 ms. Completely different results are obtained when the microphone is located 11 m from the sound source. In this case the ratio between the direct sound energy and the first reflection is as small as 1.18, or 0.7 dB, i.e. almost near one. With the second reflection, this ratio is equal to 0.8, or −1 dB, i.e. less than one. The ratio is markedly decreasing with the 3, 4, 5, 6 and 7 reflections. This is demonstrative of the fact that the influence of the first reflections over the equilibrium is much stronger at the point located relatively far from the sound source than near the source. The energy of only two reflections reaching the listener in 9.63 ms after the direct sound is sufficient to exceed the energy of the direct sound. When the microphone is 1 m from the sound source, this interval is roughly 45–50 ms.

scholarly journals Formation of an Acoustic Field in a Waveguide by a Spherical Sound Source

2020 ◽  
Vol 3 (2) ◽  
pp. 58-63
Author(s):  
Oleksandr Serhiiovych Chaika ◽  
Andrii Vitaliiovych Kozak
Keyword(s):  
Acoustic Field ◽  
Sound Source

Role of pinnae and head movements in localizing pure tones 1The authors would like to thank Mr. Remi Humbert for implementing the experiment in Turbo Pascal and for his further assistance.

1999 ◽  
Vol 58 (3) ◽  
pp. 170-179 ◽  
Author(s):  
Barbara S. Muller ◽  
Pierre Bovet
Keyword(s):  
Sound Source ◽  
Head Movement ◽  
Movement Analysis ◽  
Head Movements ◽  
Sound Sources ◽  
Localization Accuracy ◽  
Sound Effects ◽  
Posterior Quadrant ◽  
Localization Performance ◽  
Pure Tones

Twelve blindfolded subjects localized two different pure tones, randomly played by eight sound sources in the horizontal plane. Either subjects could get information supplied by their pinnae (external ear) and their head movements or not. We found that pinnae, as well as head movements, had a marked influence on auditory localization performance with this type of sound. Effects of pinnae and head movements seemed to be additive; the absence of one or the other factor provoked the same loss of localization accuracy and even much the same error pattern. Head movement analysis showed that subjects turn their face towards the emitting sound source, except for sources exactly in the front or exactly in the rear, which are identified by turning the head to both sides. The head movement amplitude increased smoothly as the sound source moved from the anterior to the posterior quadrant.

Target Detection in a Scenario of Natural Sounds: The Role of Spatial Sound Source Separation

2013 ◽  
Author(s):  
Susanne Mayr ◽  
Gunnar Regenbrecht ◽  
Kathrin Lange ◽  
Albertgeorg Lang ◽  
Axel Buchner
Keyword(s):  
Target Detection ◽  
Sound Source ◽  
Source Separation ◽  
Natural Sounds ◽  
Sound Source Separation ◽  
Spatial Sound

It's only real if you see it: Surround system based 3D sound source modelling in virtual reality

2013 ◽  
Author(s):  
Agoston Torok ◽  
Daniel Mestre ◽  
Ferenc Honbolygo ◽  
Pierre Mallet ◽  
Jean-Marie Pergandi ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Sound Source ◽  
3D Sound
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