Suggested Threshold Sound Pressure Levels For Frequency Modulated (Warble) Tones in the Sound Field

1979 ◽  
Vol 44 (1) ◽  
pp. 37-54 ◽  
Author(s):  
Donald E. Morgan ◽  
Donald D. Dirks ◽  
Deborah R. Bower
Keyword(s):  
Sound Pressure ◽  
Sound Field ◽  
Test Facility ◽  
Reference Level ◽  
Clinical Test ◽  
Reference Levels ◽  
Pure Tones ◽  
The Relationship ◽  
Narrow Bands ◽  
Reference Threshold

The problems inherent in using frequency-specific stimuli in the sound field to determine threshold sensitivity are reviewed, including a discussion of some of the specific problems encountered when introducing pure tones, narrow bands of noise, and frequency-modulated (FM) tones. The results of two experiments are reported. In Experiment I, the relationship between pure tones and frequency-modulated tones is developed under earphones in an anechoic chamber, and in two sound-isolated auditory test rooms (not anechoic). Experiment I resulted in the development of a reference threshold sound pressure level for frequency-modulated signals in the sound field. In Experiment II the reference level was applied to a clinical test facility and evaluated with a group of hearing-impaired individuals. The results suggest that the sound-field reference levels accurately reflect monaural threshold under earphones, when the earphone is calibrated to the ANSI, 1969 standard, and the sound field is calibrated to the suggested standard.

Comparison of Seven Systems for High-Frequency Air-Conduction Audiometry

1970 ◽  
Vol 13 (2) ◽  
pp. 254-270 ◽  
Author(s):  
Cecil K. Myers ◽  
J. Donald Harris
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Frequency Noise ◽  
Noise Band ◽  
Frequency Range ◽  
Pure Tones ◽  
Auditory Acuity ◽  
Narrow Bands ◽  
Reference Threshold ◽  
Air Conduction

Seven equipment systems were assembled to examine human auditory acuity from 8 to 20 kHz. Two loudspeakers and two earphones were examined, together with two types of stimulus (pure tones and narrow bands of noise) and two psychometric methods (Limits and Adjustments). All systems were capable of providing usably reliable thresholds on 28 ears throughout the whole frequency range. When carefully calibrated, several systems (those involving loudspeakers, as well as those involving earphones) yielded comparable reference threshold sound-pressure levels at the eardrum. A preference was expressed for a system using Bekesy threshold tracking with a changing-frequency noise band of 300 Hz, and for a discrete-tone system using the Method of Constants.

Observations on Relations Between Thresholds for Pure Tones and for Speech

1971 ◽  
Vol 36 (4) ◽  
pp. 476-483 ◽  
Author(s):  
Raymond Carhart
Keyword(s):  
General Formula ◽  
Pure Tone ◽  
Testing Equipment ◽  
Regression Equations ◽  
Reference Levels ◽  
Equal Importance ◽  
Statistical Studies ◽  
Pure Tones ◽  
Minimal Importance ◽  
The Relationship

The prediction of SRT for spondees from pure-tone thresholds is considered in two ways. First, review of statistical studies on the relationship between sensitivity for pure tones and SRT for spondees shows their results to be inconclusive and confusing for the clinician except to demonstrate that frequencies outside the 500–2000 Hz range are of minimal importance in estimating SRT. Second, regression equations derived from two new, audiometrically heterogeneous groups reveal that 500 and 1000 Hz carry primary and nearly equal importance as predictors of SRT when audiometric contour is not taken into account. The clinician must bear in mind that any prediction he makes must incorporate a correction constant, which will vary with the calibration of his audiometers and other variables. A reasonable general formula for predicting clinical SRTs for spondees from pure-tone thresholds when audiometric contour is not taken into account and when the testing equipment is calibrated to the new ANSI threshold reference levels is:

Hearing in Mice via GSR Audiometry

1963 ◽  
Vol 6 (4) ◽  
pp. 359-368 ◽  
Author(s):  
Charles I. Berlin
Keyword(s):  
Inverse Relationship ◽  
Sound Pressure ◽  
Single Units ◽  
Sensitivity Curve ◽  
Basic Tool ◽  
Eighth Nerve ◽  
Pure Tones ◽  
Conditioned Responses ◽  
Frequency Intensity ◽  
Near Threshold

Hearing in mice has been difficult to measure behaviorally. With GSR as the basic tool, the sensitivity curve to pure tones in mice has been successfully outlined. The most sensitive frequency-intensity combination was 15 000 cps at 0-5 dB re: 0.0002 dyne/cm 2 , with responses noted from 1 000 to beyond 70 000 cps. Some problems of reliability of conditioning were encountered, as well as findings concerning the inverse relationship between the size of GSR to unattenuated tones and the sound pressure necessary to elicit conditioned responses at or near threshold. These data agree well with the sensitivity of single units of the eighth nerve of the mouse.

Active control of the scattered radiation with a reflecting surface

2019 ◽  
Vol 67 (3) ◽  
pp. 190-196
Author(s):  
Ning Han
Keyword(s):  
Control System ◽  
Active Control ◽  
Scattered Radiation ◽  
Sound Pressure ◽  
Sound Field ◽  
Control Area ◽  
Mirror Image ◽  
Three Dimension ◽  
Control Effect ◽  
Reflecting Surface

Based on a prediction method of the scattered sound pressure, an active control system was proposed in previous work for the three-dimension scattered radiation, where all the relevant simulations and experiments were implemented in three-dimensional free sound field. However, for practical applications, such as the anti-eavesdropping system or the stealth system for submarines, the sound field conditions are usually complex, and the most common case is the one with reflecting surface. It is questionable whether the previous control system is still effective in non-free sound field, or what improvements should be operated to ensure the control effect. In this article, based on the mirror image principle, two methods of calculating the control source strengths are proposed for the scattered radiation control, and numerical simulations with one-channel and multi-channel system are implemented to detect the corresponding control effect. It is seen that the local active control for the scattered radiation is still effective, and the reduction of the sound pressure level as well as the control area is extended with the increasement of the error sensors and control sources.

scholarly journals Research on the Manufacturing Quality of Co-Cured Hat-Stiffened Composite Structure

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2747
Author(s):  
Xiangwen Ju ◽  
Jun Xiao ◽  
Dongli Wang ◽  
Cong Zhao ◽  
Xianfeng Wang
Keyword(s):  
Composite Structures ◽  
Sound Pressure ◽  
Integration Method ◽  
Complex Geometry ◽  
Sound Field ◽  
Thickness Measurement ◽  
Curing Process ◽  
The Finite Element Method ◽  
Manufacturing Quality

The stringer-stiffened structure is widely used due to its excellent mechanical properties. Improving the manufacturing quality of stringer-stiffened structure which have complex geometry is important to ensure the bearing capacity of aviation components. Herein, composite hat-stiffened composite structures were manufactured by different filling forms and bladders with various properties, the deformation of silicone rubber bladder in co-curing process was studied by using the finite element method. The thickness measurement at different positions of the hat-stiffened structure was performed to determine the best filling form and bladder property. Moreover, in view of the detection difficulties in R-zone of stringer, numerical simulation was performed to get the sound pressure and impulse response of at the R-zone of stringer by Rayleigh integration method, and an effective equipment which could stably detect the manufacturing quality of R-zone was designed to verify the correctness of sound field simulation and realize the detection of stringer. With the optimum filling form and bladder properties, hat-stiffened composites can be manufactured integrally with improved surface quality and geometric accuracy, based on co-curing process.

scholarly journals Mathematical modeling and experimental study on solid–liquid suspension separation in ultrasonic standing wave field

2021 ◽  
pp. 146134842110229
Author(s):  
Yajing Wang ◽  
Liqun Wu ◽  
Yaxing Wang ◽  
Yafei Fan
Keyword(s):  
Standing Wave ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Sound Field ◽  
Radiation Force ◽  
High Energy ◽  
Factors Affecting ◽  
Liquid Suspension ◽  
Ultrasonic Standing Wave ◽  
Solid Liquid

A new method of removing waste chips is proposed by focusing on the key factors affecting the processing quality and efficiency of high energy beams. Firstly, a mathematical model has been established to provide the theoretical basis for the separation of solid–liquid suspension under ultrasonic standing wave. Secondly, the distribution of sound field with and without droplet has been simulated. Thirdly, the deformation and movement of droplets are simulated and tested. It is found that the sound pressure around the droplet is greater than the sound pressure in the droplet, which can promote the separation of droplets and provide theoretical support for the ultrasonic suspension separation of droplet; under the interaction of acoustic radiation force, surface tension, adhesion, and static pressure, the droplet is deformed so that the gas fluid around the droplet is concentrated in the center to achieve droplet separation, and the droplet just as a flat ball with a central sag is stably suspended in the acoustic wave node.

Study on Sound Field of High Intensity Focused Ultrasound with Short Focal Length

2012 ◽  
Vol 195-196 ◽  
pp. 364-369 ◽  
Author(s):  
Jin Hua Zhao ◽  
Li Li Yu ◽  
Chun Hui ◽  
Bin Feng Huang ◽  
Chao Li ◽  
...  
Keyword(s):  
Nonlinear Effect ◽  
Sound Pressure ◽  
Focal Length ◽  
Sound Field ◽  
High Intensity Focused Ultrasound ◽  
Beam Equation ◽  
Focal Region ◽  
Interface Position ◽  
Short Focal Length ◽  
Planar Wave

In this paper, numerical simulation of sound field with short focal length is performed, which is based on spheroidal beam equation (SBE) in frequency-domain for transducer with a wide aperture angle. And we made some experiments on vitro bovine liver to explore the characteristic of sound pressure and-3dB sound focal region at different positions of incident interface. It is found that with a fixed curvature radius if the focal length is shorter under the skin, the amplitude of sound pressure will be higher on the focus and the shape of-3dB sound focal region will be smaller. When the incident interface is in the range of planar wave, nonlinear effect is strong and the focus will change with the interface position. Especially when the position is near to transition location between planar wave and spheroidal wave, the nonlinear effect is lowered. While the focus is closer to the sound source so as to burn the scarfskin easily. When the interface is in the range of spheroidal wave, the focus position changes little but the side lobe effect due to refraction is obvious. And the focusing performance of transducer will be affected. The experimental results validate the accuracy of theoretical results. It is concluded that the position of incident interface should be selected reasonably with short focal length in the treatment of superficial tissue.

Justification of Remediation Criteria of Uranium Legacy Sites

2021 ◽  
Vol 66 (4) ◽  
pp. 54-57
Author(s):  
A. Titov ◽  
N. Shandala ◽  
Yu. Bel'skih ◽  
D. Isaev ◽  
M. Semenova ◽  
...  
Keyword(s):  
Effective Dose ◽  
Radiation Safety ◽  
Annual Effective Dose ◽  
Uranium Mining ◽  
Radioactive Material ◽  
Reference Level ◽  
Federal Law ◽  
Reference Levels ◽  
Economic Activities ◽  
Safety Standards

Purpose: To present approaches to establishing the criteria for remediation of sites contaminated due to past activities of uranium mining and milling facilities. These facilities are considered today as uranium legacy. Results: This paper presents the justified reference levels expressed in terms of annual effective dose values, which are recommended for using as remediation criteria for sites contaminated due to past activities of uranium mining and milling facilities (uranium legacy sites). Depending on further use of the sites after remediation, these criteria range from 1 µSv/year, in case of temporary presence of the population, to 10 µSv/year, in case of permanent residence of the population and conducting economic activities. Conclusions: In accordance with the international basic safety standards, accepted more than 10 years ago, exposure situations from radioactive material retained from previous activities refer to the existing exposure situation. Nevertheless, neither Federal Law “On Radiation Safety of the Population” nor Radiation Safety Standards have so far introduced terms “existing exposure situation” covering exposure at nuclear and uranium legacy sites and “reference level”, which is used to assure radiation safety of the population living at legacy sites or using these sites for the purpose of the economic activities.

Interaction between Strong Sound Waves and Cloud Droplets: Theoretical Analysis

2021 ◽  
Author(s):  
Ying-Hui Jia ◽  
Fang-Fang Li ◽  
Kun Fang ◽  
Guang-Qian Wang ◽  
Jun Qiu
Keyword(s):  
Sound Wave ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sound Field ◽  
Pressure Level ◽  
Velocity Variation ◽  
Time Range ◽  
Sound Waves ◽  
Cloud Droplets ◽  
Acoustic Frequency

AbstractRecently strong sound wave was proposed to enhance precipitation. The theoretical basis of this proposal has not been effectively studied either experimentally or theoretically. Based on the microscopic parameters of atmospheric cloud physics, this paper solved the complex nonlinear differential equation to show the movement characteristics of cloud droplets under the action of sound waves. The motion process of individual cloud droplet in a cloud layer in the acoustic field is discussed as well as the relative motion between two cloud droplets. The effects of different particle sizes and sound field characteristics on particle motion and collision are studied to analyze the dynamic effects of thunder-level sound waves on cloud droplets. The amplitude of velocity variation has positive correlation with Sound Pressure Level (SPL) and negative correlation with the frequency of the surrounding sound field. Under the action of low-frequency sound waves with sufficient intensity, individual cloud droplets could be forced to oscillate significantly. The droplet smaller than 40μm can be easily driven by sound waves of 50 Hz and 123.4 dB. The calculation of the collision process of two droplets reveals that the disorder of motion for polydisperse droplets is intensified, resulting in the broadening of the collision time range and spatial range. When the acoustic frequency is less than 100Hz (@ 123.4dB) or the Sound Pressure Level (SPL) is greater than 117.4dB (@ 50Hz), the sound wave can affect the collision of cloud droplets significantly. This study provides theoretical perspective of acoustic effect to the microphysics of atmospheric clouds.

Annoyance of Low Frequency Tones and Objective Evaluation Methods

2005 ◽  
Vol 24 (2) ◽  
pp. 81-95 ◽  
Author(s):  
Jishnu K. Subedi ◽  
Hiroki Yamaguchi ◽  
Yasunao Matsumoto ◽  
Mitsutaka Ishihara
Keyword(s):  
Sound Pressure ◽  
Hearing Threshold ◽  
Low Frequency ◽  
Objective Evaluation ◽  
Evaluation Methods ◽  
Frequency Separation ◽  
Rate Of Increase ◽  
Pure Tones ◽  
Four Levels ◽  
Loudness Model

Annoyance of low frequency pure and combined tones was measured in a laboratory experiment. Three low frequency tones at frequencies of 31.5, 50 and 80 Hz at four sound pressure levels, from about 6 dB to 24 dB above average hearing threshold, were selected as pure tones. The combined tones were combinations of two tones: the four levels of 31.5, 50 and 80 Hz tones and a constant level 40 Hz tone. The results showed that the rate of increase in annoyance of pure tones with increase in the sound pressure level was higher at lower frequencies, as reported in previous studies. The results for the combined tones showed that the increase in the annoyance of the combined tone compared to the annoyance of pure tone was dependent on the level difference of the two tones and their frequency separation. These results were compared with the evaluation obtained from different objective methods. The three methods were Moore's loudness model, the low frequency A-weighting and the total energy summation used as objective evaluation methods. Among the methods, the low frequency A-weighting gave the best correlation.

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