Aircraft noise

About: Aircraft noise is a research topic. Over the lifetime, 3051 publications have been published within this topic receiving 32039 citations.

In-Flight Far-Field Measurement of Helicopter Impulsive Noise

Abstract: : An in-flight technique for measuring UH-1H helicopter impulsive noise (sometimes called 'blade slap') by stationkeeping with a quiet instrumented lead aircraft was found to be highly successful. Far-field quantitative acoustic waveforms and radiation patterns were easily obtained over a wide, continuous range of UH-1H flight conditions, including several areas known to produce annoying acoustic radiation. The data collected using this technique were not (to any significant degree) contaminated by transmission path distortions that have hindered measurement efforts in the past. The two major finding of this initial measurement program were: (1) Judging the occurrence and severity of a helicopter's radiated impulsive noise signature from cabin-based noise measurements can be misleading. For the UH-1H helicopter, reduction in cabin audible impulsive noise levels may constitute a necessary but certainly not sufficient to indicate that far-field impulsive noise radiation has been reduced. The following three distinct types of impulsive noise are radiated by the Un-1H helicopter while flying between 80 and 115 knots at descent rates from zero to 1000 ft/min: (a) A series of positive pressure pulses believed to be related to blade-tip vortex interaction. These pulses are responsible for the crisp popping sound of the radiated noise; (b) A negative pressure disturbance that rapidly increases in amplitude with forward velocity, becoming quite intense and sawtoothed in shape at 115 knots IAS; and (c) A narrow positive pressure spike that closely follows that sawtooth-shaped negative pressure pulse at high airspeeds (115 knots).

Statistical modeling of the spatial variability of environmental noise levels in Montreal, Canada, using noise measurements and land use characteristics.

Abstract: The availability of noise maps to assess exposure to noise is often limited, especially in North American cities. We developed land use regression (LUR) models for LAeq24h, Lnight, and Lden to assess the long-term spatial variability of environmental noise levels in Montreal, Canada, considering various transportation noise sources (road, rail, and air). To explore the effects of sampling duration, we compared our LAeq24h levels that were computed over at least five complete contiguous days of measurements to shorter sampling periods (20 min and 24 h). LUR models were built with General Additive Models using continuous 2-min noise measurements from 204 sites. Model performance (adjusted R2) was 0.68, 0.59, and 0.69 for LAeq24h, Lnight, and Lden, respectively. Main predictors of measured noise levels were road-traffic and vegetation variables. Twenty-minute non-rush hour measurements corresponded well with LAeq24h levels computed over 5 days at road-traffic sites (bias: -0.7 dB(A)), but not at rail (-2.1 dB(A)) nor at air (-2.2 dB(A)) sites. Our study provides important insights into the spatial variation of environmental noise levels in a Canadian city. To assess long-term noise levels, sampling strategies should be stratified by noise sources and preferably should include 1 week of measurements at locations exposed to rail and aircraft noise.

Social survey of community response to a step change in aircraft noise exposure.

Abstract: Community response to a step change in aircraft noise exposure associated with the opening of a new runway at Vancouver International Airport was documented in two rounds of telephone interviews. One round of interviews was conducted 15 months prior to the start of operations on the new runway, while a second round of interviews was undertaken 21 months after the start of operations. The proportion of respondents who described themselves as “very” or “extremely” annoyed by aircraft noise in a residential area with increased aircraft noise exposure after the runway opening was markedly greater than that predictable from well-known dosage–response relationships. Analysis suggests that a good part of the “excess” annoyance is attributable to the net influence of nonacoustic factors.

Psychological study on Leq as a measure of loudness of various kinds of noises

Abstract: The application of Leq as a measure of loudness of various noises is investigated. Nine kinds of noise sources, -aircraft noise, super express train noise, train noise, road traffic noise, speech, music, impulsive noise, artificial level-fluctuating noise and steady state noise-are used as stimuli. The duration is about10sec except for impulsive noise. Four kind levels are used in each noise source, therefore36stimuli are contained in a stimulus series. They are presented in random order and their loudness are judged by magnitude estimation. As a result of experiment, it is found that Leq can be used as a good measure of the loudness of various noises as a first approximation. Strictly speaking, however, there is a slight, but systematical deviation from Leq in PSE's of some noise sources. This fact suggests that it is necessary to add some factors to Leq in order to decide the permissible levels of these noise sources.