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Investigation of far noise field of jets 2: comparison of air jets and jet engines

Description: Report presenting a comparison of the noise generation of air jets and turbojet engines under similar free-flight conditions. Results regarding a comparison of the sound power, afterburner data, spectrum measurements, noise data for engine thrust, and frequency distribution for the two engines are provided.
Date: January 1956
Creator: Coles, Willard D. & Callaghan, Edmund E.
Partner: UNT Libraries Government Documents Department

The Effect of White Noise on a Visual Discrimination Task

Description: Previous studies have demonstrated that in some instances certain types of auditory stimulation have facilitated a subject's ability at a visual task while in other instances, the subject's ability has been inhibited. The primary objective of this experiment was to investigate the effect of auditory stimulation upon a subject's performance on a visual discrimination task.
Date: January 1969
Creator: Smith, James Larry
Partner: UNT Libraries

Spontaneous Brain Activity as a Source of Ideal 1/f Noise

Description: In this article, the authors study the electroencephalogram (EEG) of 30 closed-eye subjects with a technique of analysis recently proposed to detect punctual events signaling rapid transitions between different metastable states.
Date: December 18, 2009
Creator: Allegrini, Paolo; Menicucci, Danilo; Bedini, Remo; Fronzoni, Leone; Gemignani, Angelo; Grigolini, Paolo et al.
Partner: UNT College of Arts and Sciences

Acoustic, thrust, and drag characteristics of several full-scale noise suppressors for turbojet engines

Description: From Introduction: " Considerable analytical and experimental research has been done to find means of reducing the noise levels of the turbojet transports. Noise levels can be decreased by engine redesign to reduce the jet-exit velocity (ref. 1), proper flight-climb techniques (ref. 2), and the use of noise-suppression exhaust nozzles (refs. 3 to 5). The present report is concerned with the last method."
Date: April 1958
Creator: Ciepluch, Carl C; North, Warren J; Coles, Willard D & Antl, Robert J
Partner: UNT Libraries Government Documents Department

Preliminary flight survey of aerodynamic noise on an airplane wing

Description: Report presenting a brief series of airplane-wing aerodynamic-noise and boundary-layer-profile measurements made in flight as part of an extended investigation of boundary-layer noise. Results regarding the boundary layer data and ratio of root-mean-square sound pressure to the dynamic pressure are provided.
Date: March 2, 1956
Creator: Mull, Harold R. & Algranti, Joseph S.
Partner: UNT Libraries Government Documents Department

The Effect of Noise on Pulse Height Resolution

Description: Report wherein "[a] statistical study of base line fluctuations is used to relate noise measurements with the resolution spread of a pulse height analysis system. The resolution is inversely proportional to the signal-to-noise ratio. The proportionality constant is derived on the basis of a normal amplitude distribution for noise. A review of noise measuring techniques is given and adapted for use with electronic voltmeters. The form factors required to interpret meter readings in terms of the RMS value of noise are described" (p. 1).
Date: January 1962
Creator: Meth, Irving M. & Graveson, Robert T.
Partner: UNT Libraries Government Documents Department

Noise Pollution from Expressways

Description: This paper provides an economic analysis of three noise abatement strategies designed to interrupt the path of noise between highways and residential areas, and makes some abatement policy suggestions.
Date: June 1976
Creator: Vaughan, Roger J. & Huckins, Larry
Partner: UNT Libraries Government Documents Department

The Effects of a Masking Noise Upon the Performance of a Simple Motor Task Comparing Brain-Injured and Non-Brain-Injured Children

Description: Two questions can be posed for study: 1) Will the effect of auditory masking provided by a clinical noise significantly affect the performance of hearing children on the Knox Cube Test? 2) Are there significant differences among brain-injured, mentally, retarded, and "normal" children in ability to adjust to auditory masking in the performance of the Knox Cube Test?
Date: August 1967
Creator: Moss, Barbara A.
Partner: UNT Libraries

Noise in School Power Laboratories: Its Effects and Control

Description: This study was made to find the effects of noise on the human body, to measure sound levels that exist in school power laboratories, and to design and evaluate the effectiveness of two noise control devices. An accurately calibrated testing device was used to measure sound levels in an attempt to determine if excessive noise exists in school power laboratories and to find the extent to which such noise can be reduced by shielding or enclosing the engine test area. It was found that noise has undesirable physical and psychological effects on the human organism. Sixty-two and one-half per cent of the engines tested registered sound levels above 90 dBA; even so, simple, inexpensive noise control devices do control the noise levels generated in the school power laboratories.
Date: August 1976
Creator: Schwab, David L.
Partner: UNT Libraries

Increasing the Dynamic Range of Audio THD Measurements Using a Novel Noise and Distortion Canceling Methodology

Description: The objective of this study was to determine how a new experimental methodology for measuring Total-Harmonic-Distortion (THD) of operational amplifiers functioned when compared with two standard methodologies, and whether the new methodology offers any improvement in noise floor and dynamic range along with distortion canceling of the sine-wave source used in the testing. The new methodology (THD) is being tested against two standard methodologies: Spectral Analysis using a tuned receiver type Spectrum Analyzer with Notch Filter pre-processing, and a digitized Fast Fourier Transform (FFT) using Notch Filter pre-processing. The THD results appear to agree across all methodologies, and across all items of the sample within all methodologies, to within a percent or less. The distortion and noise canceling feature of the new methodology appeared to function as expected and in accordance with theory. The sample tested in the study consisted of thirty-five NE5534 operational amplifiers produced by Texas Instruments, Inc. and purchased from a local store. The NE5534 is a low-noise, low-distortion, operational amplifier that is widely used in industry and is representative of today's best audio amplifiers.
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: May 2003
Creator: Dunipace, Richard Alan
Partner: UNT Libraries

Near Noise Field of a Jet-Engine Exhaust

Description: From Summary: "Aircraft structures located in the near noise field of a jet engine are subjected to extremely high fluctuating pressures that may cause structural fatigue. Studies of such structures have been limited by lack of knowledge of the loadings involved. The acoustic near field produced by the exhaust of a stationary turbojet engine having a high pressure ratio was measured for a single operating condition without burning. The maximum overall sound pressure without afterburning was found to be about 42 pounds per square foot along the jet boundary in the region immediately downstream of the jet-nozzle exit."
Date: 1957
Creator: Howes, Walton L.; Callaghan, Edmund E.; Coles, Willard D. & Mull, Harold R.
Partner: UNT Libraries Government Documents Department

Noise and zero point drift in 1.7 mu m cutoff detectors forSNAP

Description: We present the results of a detailed study of the noiseperformance of candidate NIR detectors for the proposed Super-NovaAcceleration Probe. Effects of Fowler sampling depth and frequency,temperature, exposure time, detector material, detector reverse-bias andmultiplexer type are quantified. We discuss several tools for determiningwhich sources of low frequency noise are primarily responsible for thesub-optimal noise improvement when multiple sampling.The effectivenessof reference pixel subtraction to mitigate zero point drifts isdemonstrated, and the circumstances under which reference pixelsubtraction should or should not be applied are examined. Spatial andtemporal noise measurements are compared, and a simple method forquantifying the effect of hot pixels and RTS noise on spatial noise isdescribed.
Date: May 23, 2006
Creator: Smith, Roger; Bebek, Christopher; Bonati, Marco; Brown, MatthewG.; Cole, David; Rahmer, Gustavo et al.
Partner: UNT Libraries Government Documents Department