Transmission of Sound through Tied Walls: An Experimental Study

1998 ◽  
Vol 5 (2) ◽  
pp. 91-101
Author(s):  
Gülin Birlik
Keyword(s):  
Experimental Study ◽  
Experimental Work ◽  
High Frequency ◽  
Transmission Loss ◽  
Low Frequency ◽  
Sound Transmission ◽  
Sound Field ◽  
Continuous Reinforcement ◽  
Cavity Depth ◽  
Sound Transmission Class

Experimental work on the prediction of sound transmission loss, TL, of brick cavity walls, plastered on both faces, is presented. First double brick walls having either 2 cm or 5 cm cavity widths were subjected to a diffuse sound field. Then tied walls were tested. In order to assess the effect of the wall ties on TL values, two types of ties, namely unit and continuous reinforcement, were investigated. The low frequency TL of the walls was observed to be highly affected by the presence of ties. High frequency TL values were not strongly influenced by the ties. When the leaves of the double brick walls having 5 cm cavity depth were tied, regardless of the type of tie used, their Sound Transmission Class was decreased by 5 points.

High-frequency neurons in the inferior colliculus that are sensitive to interaural delays of amplitude-modulated tones: evidence for dual binaural influences

1993 ◽  
Vol 70 (1) ◽  
pp. 64-80 ◽  
Author(s):  
R. Batra ◽  
S. Kuwada ◽  
T. R. Stanford
Keyword(s):  
Inferior Colliculus ◽  
High Frequency ◽  
Low Frequency ◽  
Sound Field ◽  
Low Frequencies ◽  
Contralateral Stimulation ◽  
Binaural Stimulation ◽  
Pure Tones ◽  
Ipsilateral Stimulation ◽  
Inferior Colliculi

1. Localization of sounds has traditionally been considered to be performed by a duplex mechanism utilizing interaural temporal differences (ITDs) at low frequencies and interaural intensity differences at higher frequencies. More recently, it has been found that listeners can detect ITDs at high frequencies if the amplitude of the sound varies and an ITD is present in the envelope. Here we report the responses of neurons in the inferior colliculi of unanesthetized rabbits to ITDs of the envelopes of sinusoidally amplitude-modulated (SAM) tones. 2. Neurons were studied extracellularly with glass-coated Pt-Ir or Pt-W microelectrodes. Their sensitivity to ITDs in the envelopes of high-frequency sounds (> or = 2 kHz) was assessed using SAM tones that were presented binaurally. The tones at the two ears had the same carrier frequency but modulation frequencies that differed by 1 Hz. This caused a cyclic variation in the ITD produced by the envelope. In this "binaural SAM" stimulus, the carriers caused no ITD because they were in phase. In addition to the binaural SAM stimulus, pure tones were used to investigate responses to ipsilateral and contralateral stimulation and the nature of the interaction during binaural stimulation. 3. Neurons tended to display one of two kinds of sensitivity to ITDs. Some neurons discharged maximally at the same ITD at all modulation frequencies > 250 Hz (peak-type neurons), whereas others were maximally suppressed at the same ITD (trough-type neurons). 4. At these higher modulation frequencies (> 250 Hz), the characteristic delays that neurons exhibited tended to lie within the range that a rabbit might normally encounter (+/- 300 microseconds). The peak-type neurons favored ipsilateral delays, which correspond to sounds in the contralateral sound field. The trough-type neurons showed no such preference. 5. The preference of peak-type neurons for a particular delay was sharper than that of trough-type neurons and was comparable to that observed in neurons of the inferior colliculus that are sensitive to delays of low-frequency pure tones. 6. At lower modulation frequencies (< 150 Hz) characteristic delays often lay beyond +/- 300 microseconds. 7. Increasing the ipsilateral intensity tended to shift the preferred delay ipsilaterally at lower (< 250 Hz), but not at higher, modulation frequencies. 8. When tested with pure tones, a substantial number of peak-type neurons were found to be excited by contralateral stimulation but inhibited by ipsilateral stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Low-Frequency Broadband Sound Transmission Loss of Infinite Orthogonally Rib-Stiffened Sandwich Structure with Periodic Subwavelength Arrays of Shunted Piezoelectric Patches

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Zhifu Zhang ◽  
Weiguang Zheng ◽  
Qibai Huang
Keyword(s):  
Sandwich Structure ◽  
Transmission Loss ◽  
Virtual Work ◽  
Low Frequency ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Convergence Criterion ◽  
Sound Transmission Loss ◽  
Space Harmonic ◽  
Broadband Sound

This paper studies low-frequency sound transmission loss (STL) of an infinite orthogonally rib-stiffened sandwich structure flexibly connected with periodic subwavelength arrays of finite shunted piezoelectric patches. A complete theoretical model is proposed by three steps. First, the panels and piezoelectric patches on both sides are equivalent to two homogeneous facesheets by effective medium method. Second, we take into account all inertia terms of the rib-stiffeners to establish the governing equations by space harmonic method, separating the amplitude coefficients of the equivalent facesheets through virtual work principle. Third, the expression of STL is reduced. Based on the two prerequisites of subwavelength assumption and convergence criterion, the accuracy and validity of the model are verified by finite element simulations, cited experiments, and theoretical values. In the end, parameters affecting the STL performance of the structure are studied. All of these results show that the sandwich structure can improve the low-frequency STL effectively and broaden the sound insulation bandwidth.

Effects of Source Position and Frequency on Geoacoustic Inversion

1998 ◽  
Vol 06 (01n02) ◽  
pp. 245-255 ◽  
Author(s):  
Renhe Zhang ◽  
Fenghua Li ◽  
Wenyu Luo
Keyword(s):  
Simulated Annealing ◽  
Theoretical Analysis ◽  
High Frequency ◽  
Low Frequency ◽  
Sound Field ◽  
Propagation Model ◽  
Single Frequency ◽  
Test Cases ◽  
Source Position ◽  
Geoacoustic Inversion

In this paper, geoacoustic inversion based on simulated annealing and the BDRM propagation model is applied to the test cases from the 1997 Geoacoustic Inversion Workshop. The effects of the bottom parameters on the sound field are discussed theoretically and two characteristic angles dependent upon geoacoustic parameters are defined. Based on the theoretical analysis of the characteristic angles, a multi-frequency inversion scheme is given as follows: High frequency and farfield data are used to invert the upper bottom parameters first, and then low frequency and nearfield data are used to invert the lower bottom parameters. Simulated tests show that the results of multi-frequency inversion are more accurate and reliable than single frequency inversion.

scholarly journals Characteristics of Low-Frequency Acoustic Wave Propagation in Ice-Covered Shallow Water Environment

2021 ◽  
Vol 11 (17) ◽  
pp. 7815
Author(s):  
Shande Li ◽  
Shuai Yuan ◽  
Shaowei Liu ◽  
Jian Wen ◽  
Qibai Huang ◽  
...  
Keyword(s):  
Parabolic Equation ◽  
Target Detection ◽  
Acoustic Field ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Low Frequency ◽  
Sound Field ◽  
The Arctic ◽  
Long Distance ◽  
Propagation Law

Mastering the sound propagation law of low-frequency signals in the Arctic is a major frontier basic research demand to improve the level of detection, communication, and navigation technology. It is of practical significance for long-distance sound propagation and underwater target detection in the Arctic Ocean. Therefore, how to establish an effective model to study the characteristics of the acoustic field in the Arctic area has always been a hot topic in polar acoustic research. Aimed at solving this problem, a mathematical polar acoustic field model with an elastic seafloor is developed based on a range-dependent elastic parabolic equation theory. Moreover, this method is applied to study the characteristics of polar sound propagation for the first attempt. The validity and effectiveness of the method and model are verified by the elastic normal mode method. Simultaneously, the propagation characteristics of low-frequency signals are studied in a polar sound field from three aspects, which are seafloor parameters, sea depth, and ice thickness. The results show that the elastic parabolic equation method can be well utilized to the Arctic low-frequency acoustic field. The analysis of the influence factors of the polar sound field reveals the laws of sound transmission loss of low-frequency signals, which is of great significance to provide information prediction for underwater submarine target detection and target recognition.

scholarly journals On the Role of Acoustical Improvement and Surface Morphology of Seashell Composite Panel for Interior Applications in Buildings

Buildings ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 71 ◽  
Author(s):  
Erni Setyowati ◽  
Gagoek Hardiman ◽  
Purwanto ◽  
Mochamad Budihardjo
Keyword(s):  
Surface Morphology ◽  
High Frequency ◽  
Transmission Loss ◽  
Low Frequency ◽  
Composite Panel ◽  
Material Structure ◽  
Perna Viridis ◽  
Fibrous Layer ◽  
Anadara Granosa

This manuscript focuses on the acoustical behaviors and surface morphology of seashell waste filler reinforced polyester (SFRP) coverings Anadara granosa Linn, Perna viridis Linn, and Placuna placenta Linn and applications in buildings. Their acoustical performances were observed using an impedance tube using a technique with two and four microphones based on ASTM E1050-98 and ASTM E2611-09. The improvements of acoustical performance were conducted by a coupled resonator inclusion with addition of a fibrous dacron layer and back cavity. The experimental results showed that the resonators and back cavity on the material structure were able to shift the absorption ability at low frequency. The promising wide broadband frequencies performance occurred when the 15 mm Placuna placenta FRP treated with front-tailed cavity without any additional fibrous layer and air gap started from 0.2 at 2.0 kHz. The combination of resonators and fibrous layer on the material structure was able to stabilize the sound transmission loss (STL) in 52–56 dB at a high frequency. On the observation of the simple surface morphology material, it was found that Placuna placenta Linn had the highest damping performances due to the smallest pores and the most carbon compound compared to the others. Therefore, this finding is very useful for building applications.

Fluctuating Pressure Generating in BWR Main Steam Lines Acoustic Excited by Safety Relief Valve Stub Pipes and Dead Legs

2010 ◽  
Author(s):  
Shiro Takahashi ◽  
Keita Okuyama ◽  
Akinori Tamura ◽  
Masaya Ohtsuka ◽  
Masaaki Tsubaki ◽  
...  
Keyword(s):  
Flow Velocity ◽  
High Frequency ◽  
Acoustic Analysis ◽  
Low Frequency ◽  
Sound Field ◽  
Acoustic Resonance ◽  
Operating Conditions ◽  
Relief Valve ◽  
Fluctuating Pressure ◽  
Main Steam

During operation, the BWR-3 steam dryer in the Quad Cities Unit 2 Nuclear Power Plant was damaged by high cycle fatigue. The dryer failure was attributed to flow-induced acoustic resonance at the stub pipes of safety relief valves (SRVs) in the main steam lines (MSLs). The acoustic resonance was considered to be generated by interaction between the sound field and an unstable shear layer across the closed side branches with SRV stub pipes. We HITACHI and CRIEPI have started a research program on BWR dryers to develop their loading evaluation methods. Moreover, it has become necessary to evaluate the dryer integrity of BWR-5 plants in particular which are the main type of BWR in Japan. In the present study, we used 1/10-scale BWR tests and analyses to investigate the flow-induced acoustic resonance and characteristics of fluctuating pressure in MSLs. The test apparatus consisted of a steam dryer, a steam dome and 4 MSLs with 20 SRV stub pipes. A finite element method (FEM) was applied for the calculation of three-dimensional wave equations in acoustic analysis. We demonstrated that remarkable fluctuating pressures occurred in high and low frequency regions. Intensity of three peaks observed in the spectrum of fluctuating pressure in MSLs was increased with St. High frequency fluctuating pressures were generated by the flow-induced acoustic resonance in the SRV stub pipes. Low frequency fluctuating pressures were excited by the acoustic resonance in the dead leg. Frequency of fluctuating pressure generating in the SRV stub pipe was changed with St. On the other hand, frequency of fluctuating pressure excited by dead leg was almost constant. Fluctuating pressure in low frequency range increased gradually with flow velocity and its intensity was roughly proportional to the square of flow velocity. The flow-induced acoustic resonance did not occur for St larger than 0.6 in the BWR MSLs for both low and high frequency ranges. Operating conditions of the BWR-5 from 100 to 115% were in the range of St larger than 0.6, so intense acoustic resonance would not occur in the BWR MSLs.

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