Undirectional, Underwater‐Sound, Pressure‐Gradient Transducer

1970 ◽  
Vol 47 (1A) ◽  
pp. 71-71
Author(s):  
R. D. Marciniak
Keyword(s):  
Pressure Gradient ◽  
Sound Pressure ◽  
Underwater Sound

scholarly journals Low frequency absolute calibration of complex sensitivity of vector receivers in free-field

2019 ◽  
Vol 283 ◽  
pp. 05003
Author(s):  
Guanghui Jia ◽  
Yi Chen ◽  
Zihong Ping ◽  
Teng Fei
Keyword(s):  
Pressure Gradient ◽  
Sound Pressure ◽  
Free Field ◽  
Spherical Wave ◽  
Low Frequency ◽  
Calibration Method ◽  
Absolute Calibration ◽  
Underwater Sound ◽  
Vector Receiver ◽  
Calibration Facility

Three-transducers spherical wave reciprocity method in free-field is demonstrated effectively for absolute calibration of the complex sensitivity of underwater sound pressure gradient of vector receiver in the frequency range 250 Hz to 4 kHz. The regularity of underwater sound pressure gradient distribution in the spherical wave, the theory of three-transducers reciprocity calibration method and the technique of complex moving weighted average (CMWA) are studied and reviewed. The VHS90 vector receiver manufactured by Hangzhou Applied Acoustics Research Institute (HAARI) is calibrated using underwater sound pressure gradient calibration facility in a 50 m×15 m×10 m anechoic tank. To verify the results of measurements, the VHS90 vector receiver is also calibrated using low frequency vector receiver calibration facility and the underwater sound pressure calibration facility. The calibration results and the comparisons with these facilities prove the accuracy of the calibration method and facilities described in this paper. The max deviation of modulus of complex sensitivity is 0.7 dB and max deviation of phase congruency of three channels is 1.6°.

scholarly journals Measurement of Underwater Acoustic Energy Radiated by Single Raindrops

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2687
Author(s):  
Shu Liu ◽  
Qi Li ◽  
Dajing Shang ◽  
Rui Tang ◽  
Qingming Zhang
Keyword(s):  
Ambient Noise ◽  
Sound Pressure ◽  
Tap Water ◽  
Acoustic Energy ◽  
Underwater Sound ◽  
Underwater Noise ◽  
Energy Characteristics ◽  
Sound Energy ◽  
Dipole Radiation ◽  
Series Of Experiments

Underwater noise produced by rainfall is an important component of underwater ambient noise. For example, the existence of rainfall noise causes strong disturbances to sonar performance. The underwater noise produced by a single raindrop is the basis of rainfall noise. Therefore, it is necessary to study the associated underwater noise when drops strike the water surface. Previous research focused primarily on the sound pressure and frequency spectrum of underwater noise from single raindrops, but the study on its sound energy is insufficient. The purpose of this paper is to propose a method for predicting the acoustic energy generated by raindrops of any diameter. Here, a formula was derived to calculate the underwater sound energy radiated by single raindrops based on a dipole radiation pattern. A series of experiments were conducted to measure the underwater sound energy in a 15 m × 9 m × 6 m reverberation tank filled with tap water. The analysis of the acoustic energy characteristics and conversion efficiency from kinetic to acoustic energy helped develop the model to predict the average underwater sound energy radiated by single raindrops. Using this model, the total underwater sound energy of all raindrops during a rainfall event can be predicted based on the drop size distribution.

Comparative sensitivity of pressure gradient receivers of force and inertial types to sound pressure in plane wave

2015 ◽  
Author(s):  
Vladimir I. Korenbaum ◽  
Sergei V. Gorovoy ◽  
Alexandr A. Tagiltcev ◽  
Anatoly E. Kostiv
Keyword(s):  
Plane Wave ◽  
Pressure Gradient ◽  
Sound Pressure ◽  
Comparative Sensitivity ◽  
Inertial Types

Underwater sound pressure and particle motion (acceleration, velocity, and displacement) from recreational swimmers, divers, surfers, and kayakers

2018 ◽  
Vol 143 (3) ◽  
pp. 1712-1712
Author(s):  
Christine Erbe ◽  
Miles Parsons ◽  
Alec J. Duncan ◽  
Klaus Lucke ◽  
Alexander Gavrilov ◽  
...  
Keyword(s):  
Particle Motion ◽  
Sound Pressure ◽  
Underwater Sound

Relationship of swim-bladder shape to the directionality pattern of underwater sound in the oyster toadfish

1998 ◽  
Vol 76 (1) ◽  
pp. 134-143 ◽  
Author(s):  
John F Barimo ◽  
Michael L Fine
Keyword(s):  
Sound Source ◽  
Sound Pressure ◽  
Sound Production ◽  
Swim Bladder ◽  
Underwater Sound ◽  
York River ◽  
Coefficients Of Variation ◽  
Source Level ◽  
Oyster Toadfish ◽  
Relationship Of

The swim bladder of the oyster toadfish, Opsanus tau, has a distinctive heart shape with two anterior protrusions separated by a midline cleft. The lateral surfaces contain intrinsic muscles that meet at the caudal midline, but the rostromedial surface is muscle-free. We hypothesize that swim-bladder design represents a compromise between opposing tendencies toward (i) an omnidirectional sound source that would optimize a male's opportunity to attract females from any direction, and (ii) a directional sound source that would shield the nearby ears during sound production. To determine if the directionality of toadfish sound is consistent with this hypothesis, boatwhistle advertisement calls of individually identified males were recorded in the York River, Virginia, by means of two calibrated hydrophones and a waterproof recording system: one hydrophone was fixed 1 m in front of the fish and the second was roving. Boatwhistles in the horizontal plane propagated in a modified omnidirectional pattern that was bilaterally symmetrical. The mean sound pressure was 126 dB re: 1 µPa at 0°. The sound pressure level decreased by approximately 1 dB at ±45°, after which levels increased to 180°, averaging 3-6 dB greater behind (mean 130 dB) than directly in front of the fish. This pattern is consistent with the hypothesis that sound energy is reduced at the fish's ears. The source level and fundamental frequency of the boatwhistle were highly stereotyped, with coefficients of variation averaging less than 1%, and duration was more variable, with a coefficient of variation of 8%. Grunt levels overlapped but were slightly lower than boatwhistle values.

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