Effect of Stimulus Duration on Localization of Direction of Noise Stimuli

1970 ◽  
Vol 13 (4) ◽  
pp. 826-838 ◽  
Author(s):  
Willard R. Thurlow ◽  
James R. Mergener
Keyword(s):  
Stimulus Duration ◽  
Head Movement ◽  
High Frequency ◽  
Thermal Noise ◽  
Low Frequency ◽  
Frequency Noise ◽  
Noise Sources ◽  
Minimum Duration ◽  
High Frequency Noise ◽  
Efficient Performance

Localization of the direction of bursts of thermal noise was measured for both high-frequency and low-frequency bands, as a function of duration of bursts. Durations of 0.3, 1, 2, and 5 sec were used. Subjects were free to move their heads to aid in localization. Subjects were not specially trained in sound localization. With increase in stimulus duration, perception of elevation was slightly improved for low-frequency noise, probably due to increased information from head movement. A minimum duration of the order of 2 sec appears necessary to allow subjects to achieve maximum performance (which still is not very good for these low-frequency stimuli). Perception of the elevation of the high-frequency noise sources we used was relatively good even at the briefest duration; however, variability of judgment was larger at the shorter durations. Perception of front-back source position was much improved for both low-frequency and high-frequency noise when stimulus duration was increased. The results are understandable in terms of the increased possibility for head movement with increase in stimulus duration. It appears that one should use a minimum stimulus duration of about 2 sec if one wishes subjects to approach their most efficient performance.

Aerodynamic noise from an asymmetric airfoil with perforated extension plates at the trailing edge

2020 ◽  
pp. 1475472X2097838
Author(s):  
CK Sumesh ◽  
TJS Jothi
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Pore Diameter ◽  
Low Frequency ◽  
Aerodynamic Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Trailing Edge ◽  
High Frequency Noise ◽  
Displacement Thickness

This paper investigates the noise emissions from NACA 6412 asymmetric airfoil with different perforated extension plates at the trailing edge. The length of the extension plate is 10 mm, and the pore diameters ( D) considered for the study are in the range of 0.689 to 1.665 mm. The experiments are carried out in the flow velocity ( U∞) range of 20 to 45 m/s, and geometric angles of attack ( αg) values of −10° to +10°. Perforated extensions have an overwhelming response in reducing the low frequency noise (<1.5 kHz), and a reduction of up to 6 dB is observed with an increase in the pore diameter. Contrastingly, the higher frequency noise (>4 kHz) is observed to increase with an increase in the pore diameter. The dominant reduction in the low frequency noise for perforated model airfoils is within the Strouhal number (based on the displacement thickness) of 0.11. The overall sound pressure levels of perforated model airfoils are observed to reduce by a maximum of 2 dB compared to the base airfoil. Finally, by varying the geometric angle of attack from −10° to +10°, the lower frequency noise is seen to increase, while the high frequency noise is observed to decrease.

Effects of Noise Frequency on Performance and Annoyance for Women and Men

1981 ◽  
Vol 52 (2) ◽  
pp. 435-441 ◽  
Author(s):  
Kelli F. Key ◽  
M. Carr Payne
Keyword(s):  
Sex Differences ◽  
Magnitude Estimation ◽  
High Frequency ◽  
Ambient Noise ◽  
Direct Relationship ◽  
Low Frequency ◽  
Frequency Noise ◽  
Complex Task ◽  
High Frequency Noise ◽  
Noise Frequency

Effects of noise frequencies on both performance on a complex psychomotor task and annoyance were investigated for men ( n = 30) and women ( n = 30). Each subject performed a complex psychomotor task for 50 min. in the presence of low frequency noise, high frequency noise, or ambient noise. Women and men learned the task at different rates. Little effect of noise was shown. Annoyance ratings were subsequently obtained from each subject for noises of various frequencies by the method of magnitude estimation. High frequency noises were more annoying than low frequency noises regardless of sex and immediate prior exposure to noise. Sex differences in annoyance did not occur. No direct relationship between learning to perform a complex task while exposed to noise and annoyance by that noise was demonstrated.

scholarly journals High-Frequency Noise Sources in Quantum Wells

2002 ◽  
Vol 102 (2) ◽  
pp. 329-335
Author(s):  
L. Ardaravičius ◽  
J. Liberis ◽  
A. Matulionis
Keyword(s):  
Quantum Wells ◽  
High Frequency ◽  
Frequency Noise ◽  
Noise Sources ◽  
High Frequency Noise

Evidence for the existence of locally-generated body waves in the short-period noise at the Large Aperture Seismic Array, Montana

1972 ◽  
Vol 62 (1) ◽  
pp. 13-29 ◽  
Author(s):  
H. M. Iyer ◽  
John H. Healy
Keyword(s):  
Statistical Analysis ◽  
Phase Velocity ◽  
High Frequency ◽  
Seismic Noise ◽  
Average Velocity ◽  
Low Frequency ◽  
Body Waves ◽  
Frequency Noise ◽  
High Frequency Noise ◽  
Short Period

Abstract The approximate hexagonal configuration of LASA subarrays enables their use as omnidirectional arrays. This property is used to study the phase velocity of short-period seismic noise at different frequencies. It is found that the noise in the low-frequency band consists mainly of surface waves traveling with average velocities in the range 3.0 to 3.5 km/sec. The high-frequency noise, in the band 0.45 to 1.0 Hz, has an average velocity of about 6.0 km/sec. It is quite likely that the high-frequency noise has the nature of locally-generated body waves. Statistical analysis of Pg velocities observed during a crustal refraction experiment at LASA lends support to this hypothesis.

Study of the Coherence of Acoustic Fields of High-Frequency Noise Sources in a Randomly Inhomogeneous Ocean

2018 ◽  
Vol 64 (2) ◽  
pp. 215-224 ◽  
Author(s):  
A. I. Khil’ko ◽  
I. P. Smirnov ◽  
A. I. Mashonin ◽  
A. V. Shafranyuk
Keyword(s):  
High Frequency ◽  
Frequency Noise ◽  
Acoustic Fields ◽  
Noise Sources ◽  
High Frequency Noise

Burial Process of a Seismic Station by Moving Dunes in Tarim Basin

2020 ◽  
Vol 91 (5) ◽  
pp. 2936-2941
Author(s):  
Xiaofeng Liang ◽  
Sicheng Zuo ◽  
Shilin Li ◽  
Yongge Feng
Keyword(s):  
High Frequency ◽  
Noise Level ◽  
Seismic Station ◽  
Low Frequency ◽  
Seismic Signal ◽  
Frequency Noise ◽  
Temperature Record ◽  
Environment Change ◽  
Broadband Seismometer ◽  
High Frequency Noise

Abstract A temporary seismometer vault was buried by a moving sand dune in the Taklimakan Desert at northwestern China in October 2019. The dune gradually covered the solar panel and the power supply to the seismic station was subsequently cut off. Here, we show that the burial process can be diagnosed according to the temperature record from the thermometer in the data-logger, an ultra-low-frequency seismic signal, and the change of high-frequency noise level from the continuous seismograms recorded by the broadband seismometer. The ultra-low-frequency seismic signal reflects the thermoelastic effect of the suspension spring in the seismometer corresponding to the temperature gradient in the sensor vault. At the same time, the variation of high-frequency noise level correlates well with the temperature profile and the ultra-low-frequency seismic signal, indicating the ground wind intensity. The peak frequency shifts and their different responses on three-component waveforms for the high-frequency noise might reflect the distance from the moving dunes to the station and their moving directions. This observation shows a potential usage of continuous seismograms to study rapid environment change around a temporary seismic station.

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