Annoyance due to multiple airplane noise exposure

A laboratory study was conducted to investigate the annoyance effects of multiple aircraft noise exposure in which 250 subjects judged the annoyance of half-hour periods of airplane noise simulative of typical indoor home exposures. The variables of the aircraft noise exposure were the peak noise level of flyovers, which was constant within each period, and the number of flyovers. Each subject judged 5 of the possible 25 factorial combinations of level and number. Other variables investigated included the experience of the test subjects in making annoyance judgments and their home exposure to airplane noise. The annoyance judgments increased with both noise level and number of flyovers. The increased annoyance produced by doubling the number of flyovers was found to be the equivalent of a 4 to 6 db increase in noise level. The sensitivity of the subjects to changes in both noise level and number of flyovers increased with laboratory experience. Although the means of the annoyance judgments made in the laboratory were found to decrease with the subjects' home exposure to aircraft noise, the subjects' sensitivities to changes in both level and number were unaffected by their home exposure

Laboratory study of annoyance to combined airplane and road-traffic noise

The annoyance of noise, which consisted of both separate and combined airplane and road-traffic noises, was studied. The subjects judged each session as to how annoyed they were in the simulated living room laboratory environment and as to how annoyed they were if they heard the noise in their home during day, evening, and night periods. The airplane noises, for equal session levels were judged significantly more annoying than the road traffic noises for the separate sessions. For the combined sessions, an interaction was found between the airplane noise and traffic noise levels, which was not adequately assessed by the total energy concept. Significant differences were found between the projected home responses for the day, evening, and night periods

A summation and inhibition model of annoyance response to multiple community noise sources

A model of annoyance due to combined noise sources was developed. The model provides for the summation of the subjective magnitudes of annoyance due to the separate noise sources and for the inhibition of the subjective magnitudes of each source by the presence of the other noise sources. The inhibition process is assumed to mathematically obey a power-group transformation. The results of an experiment in which subjects judged the annoyance of 15 minute sessions of combined aircraft and with several other models of combined source annoyance. These comparisons indicated that the model developed herein provides better qualitative and quantitative agreement with experimental responses than the other models. The application of the model to multiple community noises is discussed

Effects of road traffic background noise on judgments of individual airplane noises

Two laboratory experiments were conducted to investigate the effects of road-traffic background noise on judgments of individual airplane flyover noises. In the first experiment, 27 subjects judged a set of 16 airplane flyover noises in the presence of traffic-noise sessions of 30-min duration consisting of the combinations of 3 traffic-noise types and 3 noise levels. In the second experiment, 24 subjects judged the same airplane flyover noises in the presence of traffic-noise sessions of 10-min duration consisting of the combinations of 2 traffic-noise types and 4 noise levels. In both experiments the airplane noises were judged less annoying in the presence of high traffic-noise levels than in the presence of low traffic-noise levels

Annoyance due to simulated blade-slap noise

The effects of several characteristics of blade slap noise on annoyance response were studied. These characteristics or parameters were the sound pressure level of the continuous noise used to simulate helicopter broadband noise, the ratio of impulse peak to broadband noise or crest factor, the number of pressure excursions comprising an impulse event, the rise and fall time of the individual impulses, and the repetition frequency of the impulses. Analyses were conducted to determine the correlation between subjective response and various physical measures for the range of parameters studied. A small but significant improvement in the predictive ability of PNL was provided by an A-weighted crest factor correlation. No significant improvement in predictive ability was provided by a rate correction

Multiple-event airplane noise annoyance

The annoyance of sessions of airplane noise which contained different noise levels and numbers of flyovers was investigated. The time of occurrence of the high noise level flyovers in the sessions did not significantly affect annoyance, but annoyance increased with the number of such flyovers. Annoyance decreased with test session duration but increased with the total number of flyovers in the test sessions. It is found that the results support an average energy model better than a total energy model, the annoyance decay model, or the dB(A) peak concept

Relict diagenetic textures and structures in regional metamorphic rocks, northern Michigan /NASA geological test site number 126/

Relict diagenetic textures and structures in regional metamorphic rocks, northern Michiga

Nuclear Magnetic Resonance in Low-Symmetry Superconductors

We consider the nuclear spin-lattice relaxation rate, $1/T_1T$ in superconductors with accidental nodes. We show that a Hebel-Slichter-like peak occurs even in the absence of an isotropic component of the superconducting gap. The logarithmic divergence found in clean, non-interacting models is controlled by both disorder and electron-electron interactions. However, for reasonable parameters, neither of these effects removes the peak altogether.Comment: 10 pages, 5 figure

Effects of a traffic noise background on judgements of aircraft noise

A study was conducted in which subjects judged aircraft noises in the presence of road traffic background noise. Two different techniques for presenting the background noises were evaluated. For one technique, the background noise was continuous over the whole of a test session. For the other, the background noise was changed with each aircraft noise. A range of aircraft noise levels and traffic noise levels were presented to simulate typical indoor levels

The design of a numerically controlled drilling system using fluidic elements 1966/7

This report outlines the aims of the project and procedures used to bring it to a successful conclusion. It also summarises the results of an investigation into the parameters which govern the specification of a numerically controlled point to point drilling machine